"Getting into the air is not easy." "For many birds it is by far the most exhausting bit of the whole business of flight." "But these shearwaters here in Japan have adopted a very labour-saving way..." "Whoops!" "There we go, a labour-saving way of doing so." "They've taken to climbing trees." "This particular tree is by far the most suitable for the take-off, and that bird may have come from as far as 30 or 40 yards away, wandering across the forest floor in order to climb it and get to the launch pad." "There's another." "40 feet up, a bend in the trunk makes a perfect platform for a take-off." "These shearwaters will spend most of their lives in the air." "They are true seabirds." "They only come to land in order to nest." "This particular species is exceptional in nesting in woodland, most of them nest right on the edge of cliffs and all of them get into the air by the simple method of simply falling into space." "The land birds, on the other hand, have much greater problems." "Most of them have to be able to get into the air from the ground with a standing start." "And that takes a lot more energy." "A pigeon begins by jumping vertically upwards." "As it leaves the ground, it opens its wings and sweeps them forward, fanning the air downwards with maximum force." "The second stroke must be equally vigorous, pushing the bird upwards." "If now it leans forward and starts to go ahead." "But the effort involved has been huge." "Birds only a little bigger than a pigeon can't do this twice in quick succession." "And a bird as big as an albatross can't do it at all." "It has to use yet another way of getting into the air." "It taxies, along a runway." "It's a method we use too, in our machines." "For the majority of birds the most exhausting part of flight is now over." "Those shearwaters achieved it by climbing trees, the pigeon jumped and flapped, and aeroplanes and albatross did it by running and creating a flow of air over their wings." "When they do actually get into the air, a bird's flight seems almost effortless." "And when you watch a really superb flyer like these albatross, then they seem to be defying the law of nature." "They are, after all, big heavy birds." "How is it that they can withstand the pull of gravity that keeps the rest of us tied so firmly to the ground?" "The secret is a wing with a thick, rounded front edge that curves gently downwards towards the back edge, which is very thin." "As thin, in fact, as a feather." "As the bird glides forward, the air flowing under the wing is impeded by the wing's downward curve." "So it becomes slightly compressed and that pushes the wing up." "At the same time, the air flowing across the top of the wing is deflected upwards by the wing's front edge so reducing its pressure." "If the air is moving fast enough, then the slight suction from above combined with the push from beneath will be enough to lift the bird into the air, as it did during take-off, and ample to keep it aloft, as it's doing now." "The trick is to make sure that the air does flow over the wing sufficiently quickly." "Upward air currents can also sustain a bird in flight and that is just what are created when breezes, blowing in from the sea, hit a cliff." "If they are really strong, such up-draughts can be so powerful that they alone will keep an albatross in the air." "Out at sea, the waves deflect the wind upwards in somewhat smaller gusts and the albatross is so skilful that it can sail on them for hours with scarcely a movement of its wings." "Most birds, however, once in flight, have to create that air-flow across their wings by another method." "They drive themselves forward by flapping." "This knot is 'rowing' through the air, stretching its wings forwards, and beating them downwards." "On the upstroke it half-folds them, to reduce their surface area and therefore their resistance to the air." "The feathers on its wing slide smoothly over one another so that although the wing is continuously changing shape, its surface remains perfectly smooth and streamlined." "Its body is also streamlined by its coat of feathers, and its feet are pressed against its tail so that drag is kept to a minimum." "This mallard is flying at nearly 40 miles an hour, but its streamlining is so perfect that there is scarcely a ruffle to its feathers." "It's only from behind that you notice the little flicks of the feathers over its tail and the back edge of its wings which showjust how fast it's travelling." "To see just how important streamlining is, and how much energy it can save, just watch this osprey as it goes fishing." "To take off again, with the fish in its talons, the bird has to beat its wings with allthe strength it can muster." "But even now it is in the air, the fish hanging broadside." "It creates so much drag that the osprey has great difficulty in making any headway at all." "But it knows how to solve the problem." "Gripping the fish with just one foot, it manages to bring its other foot forward." "Now, using both feet, the bird changes the position of the fish so that it faces ahead and its streamlined shape reduces its drag so much that the osprey's wing-beats become almost leisurely." "Flying in formation also saves energy." "A big bird like a pelican creates a trail of turbulence in the air and this can give a following bird lift." "The effect is at its greatest directly behind a bird's wing-tip, so that is the best place for a following bird to fly." "Pelicans also save some 20% of their energy by mixing flapping with gliding." "Aerodynamically it's more profitable for a bird to time its flaps with those of the bird ahead." "So it is the pelicans who give breathtaking displays of synchronised formation flying." "The most economicalway of flying, however, is to draw almost allthe energy you need directly from the sun." "As it warms the ground in the morning, the rocks reflect its heat and shimmering columns of air, thermals, begin to rise." "Griffin vultures in Spain now leave the ledges on the cliffs where they have spent the night and launch themselves into the air." "With the thermals rising powerfully beneath their outstretched wings they sail effortlessly upwards." "Allthey have to do is to make sure that they remain within the column of warm air." "So dozens of them spiraltogether in tight circles, adjusting their flight with the tiniest movements of their wings and tails." "There can be no more economicalflight than this." "The vulture's ability to 'read' the air conditions above their landscape, and detect exactly where the thermals are at their most powerful, seems almost uncanny." "But in recent years, human beings have also mastered it." "When you hit a thermal in a glider, you really feel it." "Your stomach drops beneath your feet." " Oohh!" " I'm going to roll into the thermal here." "Glider pilots spend a lot of time going around in circles just as birds of prey do, because a thermal's a rising column of air and in order to stay in it you have to turn." "There's nothing to see though, is there?" "Apart from what's on the ground." "You can't see anything in the air to indicate a thermal." "Right now there's no cumulus cloud over this thermal." "But often there is." "If you look over there, you can see allthose cumulus clouds." "Underneath most of those there would be a thermal, and that's one of those indicators of lift, that's one thing we look for, and that's what birds look for also when they fly, I'm sure." "Feelthat!" "Now there's a big rocky outcropping." "Just look at that." "Now you can see the altimeter winding up." "Look at that." " How high could we go with this?" " Probably up to 14-15,000 feet with no problem." " And do the birds go as high as that?" " I've seen birds up to 16-18,000 feet." " They are just out there flying for fun." " How do you know that?" "Because how can you see a mouse from 18,000 feet?" "Not hardly." "And they do all kinds of tricks and aerobatics." "Look at this." "We're really going up now." "The pressure on the wings is actually bending them, isn't it?" "The spar is slightly flexible, so when you develop more lift, the spar actually bends upwards a little bit." "Very similar to a bird." "Every flight has to end in a landing." "That requires less energy, but perhaps more skill if disaster is to be avoided, particularly if you are a big bird like a pelican." "A swan, one of the heaviest of flying birds, can only come down on the smoothest and most forgiving of natural surfaces; water." "There you can use your feet as brakes." "Albatross are not so lucky." "They have to alight on the ground." "Indeed their landings seem scarcely better than controlled accidents." "Most birds, however, have to come down with much greater precision than that." "They may have to land, after all, on a narrow ledge or a very thin branch." "To do that they have to lower their flaps, put down the undercarriage and put on their brakes so that they lose all air speed at the precise moment that they come alongside their perch." "That requires great judgement and co-ordination." "A Griffin vulture is able to exploit the position of its nest, which is nearly always on the ledge of a cliff." "It descends towards it at speed." "It aims for a point below its nest and then brakes by swooping upwards so that as it arrives at its ledge its forward speed is zero." "Landing into the wind helps any bird by keeping air flowing over the wings and maintaining lift untilthe last moment." "So, one way or another, birds manage to complete an operation fraught with danger, with virtually total success." "As anyone who has had to pay for excess baggage at an airport knows, if you travel by air, it is important to keep your weight down." "This magnificent golden eagle manages to do that in a most thoroughgoing way." "It's about the same size, I suppose, as a bulldog." "But I couldn't hold a bulldog on my wrist." "But this bird only weights about a quarter as much." "So how do birds manage to keep so light?" "A beak is not so weighty as the bony jaws and teeth of a mammal like a bulldog or one of the birds' reptilian ancestors." "Its disadvantage is that a bird can't chew." "It can pluck, crush or, like an eagle, tear and rip." "They also have weight-saving features inside their bodies, a skeleton with fewer bones than a mammal's, no tail-bone, one wing-bone instead of five fingers, and a slim pelvis fused to the backbone." "And the bones themselves are not solid like a mammal's, but hollow." "Inside they have a lattice of cross-struts so they are nonetheless very strong." "But the most remarkable weight-saving features of all are those things that only birds possess:" "their feathers." "They look simple, but in fact they have a very complex structure." "The quills are hollow and very light, yet resilient and extremely strong." "The filaments on either side of the quills are fringed with microscopic hooks that link them to their neighbours so that they all latch together to form a continuous surface." "And that means that if a feather gets damaged or over-strained, it can be repaired instantly." "It can be zipped up." "Not surprisingly, all birds lavish a great deal of attention on their feathers." "After all, their lives depend on them." "And since birds have no hands, they have little alternative but to care for them with their beaks." "But one bird, uniquely, can't do that." "The sword-billed hummingbird has a beak that is so long that there is no way that its tip can touch its feathers." "It has to comb its plumage with one foot while balancing on its perch with the other." "Not easy!" "A good bath is also important in keeping the feathers clean and in first-class condition." "Most birds take one every day and, watching them doing so, it's difficult to avoid coming to the conclusion that they enjoy it just as much as we do." "Not all birds, of course, can get to water that is deep enough for bathing." "Then, like the quailthat lives on dry plains and during the summer seldom finds so much as a puddle, they may have to use dust." "This may not exactly make them cleaner, but it does, apparently, help in dislodging parasites such as lice that nibble their feathers, mites that scavenge bits of dead skin and ticks that suck their blood." "Many parrots and cockatoos grow specialfeathers that fray at the end into a fine powder." "These feathers are scattered throughout the plumage, and as a bird such as a cockatoo scratches itself at the end of its toilet, the powder is dislodged in clouds and is caught in its ruffled feathers." "Exactly how this powder improves the feathers is not really certain, but it is probable that it helps with waterproofing as well as by discouraging parasites." "Parasites, in fact, are such a problem that some birds are thought to recruit assistants to help in getting rid of them." "Ants!" "Crows and jays deliberately land on an ant's nest and stir up the colony so that the angry insects come rushing out and swarm all over them." "In their irritation the ants discharge formic acid which is a particularly powerful insecticide." "But we don't really understand this behaviour." "It may be that the birds are stimulating the ants to get rid of their formic acid so that they are more digestible as meals." "Regular, meticulous maintenance is essential for maximum efficiency and safety in the air, and that applies to everything that flies." "Well, that was about 500 miles an hour and of course birds can't equalthat." "But nonetheless, before aeroplanes were invented, a bird was the fastest living thing in the air." "The peregrine holds the record." "Diving on its prey it can exceed 200 miles an hour." "It achieves maximum aerodynamic efficiency by sweeping back its wings, like the jet fighter." "Then it accelerates by beating them." "The barn owl, on the other hand, owes its success as a hunter to its ability to fly extremely slowly." "It hunts voles and mice and, to find them in the grass it has to search very intently, and that takes time." "Its wings therefore are shaped very differently from a peregrine's." "They are rounded in outline and much broader which gives the maximum lift at slow speeds." "But the barn owl also has a very special adaptation for this kind of hunting." "The rodents it seeks are often invisible from the air, hidden beneath the matted grass." "The barn owl detects them by the rustling sounds they make." "To do that, it has extremely acute hearing, the sounds being focused by the hair-like feathers of the discs on either side of its head." "But if it is to hear them it has to fly very quietly indeed, and its wings are fitted with silencers." "Fluffy margins to its wing feathers." "So, in the evenings, a barn owl can waft over the countryside as silent as a moth." "This little dot, suspended in the sky, might seem to be the slowest flyer of all." "It's a kestrel." "It's not, in fact, truly stationary." "It's facing into a gentle wind, so there is a current of air passing over its wings." "And that gives it allthe lift it requires." "Silence is not as important for the kestrel as it is for the barn owl, for it hunts by sight." "The wind has dropped a little." "Now, to keep its position relative to the ground it has to flap to keep the air moving over its wings." "It's spotted something, a quick turn into the wind, and a drop;" "a turn back to face the wind for a stationary check;" "another quick look;" "but whatever it was, has gone." "Only one group of birds can manage to hover for any length of time without the help of a head-wind:" "the hummingbirds." "Their wings work in a way quite unlike that used by any other birds." "They beat routinely 25 times a second, so fast that they make the humming noise that gives them their name." "It is impossible to see how they operate unless the camera slows them down." "The wings have become, in effect, twirling blades that create down-draughts, rather like those that man produces with his hovering machines." "Helicopters, however, have a very special device, a wheel revolving continuously on an axle." "No bird or any other animal has yet evolved a mechanism that can exactly parallelthis." "But hummingbirds have the next best thing:" "wings which beat in a figure of eight and flick over on the backstroke." "Unlike the wings of other birds, they are symmetrical in cross-section and work equally well with either surface uppermost." "By changing the angle of the beat, the thrust can be directed not only downwards, but either forwards or backwards." "So a hummingbird, steering with its tail, can move through the air in any direction." "Beating wings at such speed, however, uses a lot of fuel." "Even at rest, hummers need a great deal just to keep their bodies ticking over." "So they have to refuelvery frequently." "But their fuel stations, flowers, close at night." "What do they do then?" "This is a particular problem in the Andes, where the nights can be very cold indeed." "As evening comes on, the hillstar hummingbird makes its way to its regular roosting place, in a cave." "After its regular toilet, it settles down for the night, and in effect turns off all its motors." "Its heart, that in flight contracted a thousand times a minute, slows until its beat is virtually undetectable." "Its body temperature falls dramatically and its breathing seems to cease altogether." "It is doing what a hedgehog does in winter, it is hibernating." "But for a hummingbird, winter comes 365 times a year." "The sun returns, and the temperature begins to rise." "The hillstar starts up its motors." "Its heart beat accelerates, its muscles slowly warm to flying temperature." "A quick pre-flight check." "And it's off again." "At higher altitudes, it seldom gets really warm even at midday." "This is the territory of the giant hummingbird." "It's as big as a thrush." "Great size helps in retaining body heat, but this is as big as a hummingbird can get." "Any larger and it couldn't beat its wings fast enough for this kind of flight." "And this is one of the smallest of all birds, the purple-collared woodstar from Ecuador with a wingspan of scarcely more than two inches." "Smallwings are easier to flap, but the smaller they are, the faster they have to move to produce sufficient downwards thrust, and this hummingbird can beat its wings at an astonishing 75 times a second." "It is barely bigger than a moth." "Indeed this moth looks so like a tiny hummingbird that some people in the south of England, where it appears regularly in the summer, think that they have been visited by a real hummer." "The ability to fly gave birds the freedom of the planet." "Rivers, deserts, seas, even mountain ranges are no obstacle to them as they are to land-bound creatures such as ourselves." "They can fly relatively easily and quickly to collect a sudden glut of food." "And that is exactly what has happened here." "I'm in northern Canada." "It's June, the beginning of the short Arctic summer." "The rising temperatures have caused the plants to put out new leaves and roots, and tens of thousands of snow geese have come here to graze." "They nested almost as soon as they arrived and many have already got families." "Even hummingbirds have come up to the far north to collect nectar from the bushes that are now briefly blooming within sight of glaciers." "On the Arctic coasts, little waders, western sandpipers, are collecting a rich harvest of smallworms that are swarming in the mud." "In the middle of the continent, on the prairies, sorghum and other grain crops are ripening in the summer sun." "Dickcissels, relatives of the common sparrow, have come up here to take their percentage." "The warm weather has caused swarms of insects to hatch and they provide the dickcissels with the protein that is essential for the nourishment of their swiftly growing young." "Hawks are also breeding here in the north." "They were attracted by the seasonal abundance of voles and other small mammals, as well as the finches and songbirds that they need to feed their young." "But the superabundance of summer is brief." "By the end ofJuly the days are noticeably shortening." "Many of the trees are preparing to shed their leaves." "The birds that flew up for the summer banquet can no longer stay." "All across the northern hemisphere the story is the same." "From eastern Siberia across Asia and Europe, to the woodlands and tundra of north America, birds are starting to fly south." "The sandpipers are stocking up for the 6,000 mile journey that lies ahead of them." "They eat so voraciously that they will nearly double their weight, putting on layers of fat on their upper thighs and their flanks." "They even shrink their internal organs, partially absorbing them as though they were food reserves and replacing them with more readily available fat." "They must wait for the right weather conditions, and then, when the wind blows strongly from the north, they set off." "Hawks and vultures are also now finding it harder to discover any food." "They too must prepare to leave." "But the weather they require for theirjourneys is rather different." "They need a good hot day when the thermals are shimmering upwards from the rocks that are stillwarming in the late summer sun." "As the last thermals of summer start to rise, the birds circle up to great heights, 10,000 feet or more, to give themselves a good start for the long journey ahead." "As they glide southwards, slowly losing height, they will look for another thermal and make for its base so that once again they will be lifted high enough to reach the next." "The snow geese are already on their way, their departure triggered by the shortening days and the dropping temperatures." "They will rely on straightforward muscle power." "They willtravel continuously for great lengths of time, both through the day and the night." "The raptors, however, have had to stop to overnight in a roost." "Without thermals they can't travelfar." "But the snow geese fly on." "The exertion of continuously beating their wings creates a lot of heat in their bodies, so travelling in the cool of the night does, in fact, suit them." "They navigate by the stars." "If the skies are heavily overcast for long periods they may lose their way, but that is exceptional." "Day returns and the stars fade." "Now they steer by the sun." "But the sun, of course, moves from east to west during the day, so the fact that they are able to use it for navigation means that they must have internal clocks and know fairly exactly what the time is." "Members of the same family traveltogether, calling to one another as they go." "And the geese have made it." "One of them has been recorded as covering an astonishing 1,700 miles in a mere 70 hours." "These fields in California will be their home untilthey return north on their spring migration." "The sandpipers have gone even further." "They have now reached Mexico." "But they will spend only a few days here for this is merely a refuelling stop." "They feed intensively, replacing the fat reserves that they have lost." "The raptors, so conscious of the nature of the land beneath them that generates thermals on which they depend, also look to it for their signposts." "They are now passing Mexico's highest mountain, the Pico de Orizaba." "There are no thermals to be found over the sea, so they are tied to the land, and that means they have to go allthe way round the western side of the Gulf of Mexico." "There is, of course, a short cut, directly south across the sea." "Astonishingly, the little ruby-throat hummingbird tackles that 500 mile long journey." "It must necessarily be non-stop for a hummingbird cannot land on the water." "A feeder in Texas provides a ruby-throat with a finaltop-up of nectar." "Its cruising speed is about 27 miles an hour." "So, if conditions are good, it could make the crossing by flying for a little over 18 hours." "But that is right on the very limit of its endurance." "If even a light head-wind springs up it will perish at sea." "Delphiniums blooming on the Mexican shore await with life-saving nectar." "A ruby-throat arrives after its epicjourney and feeds urgently before it runs out of fuel, and it's fatally grounded." "But even now its journey is not finished." "It still has several hundred miles to go and may travel as far as the Panama border." "The hawks and vultures, travelling round the western side of the Gulf, have now reached Panama City." "They came from all over North America, converged on the Isthmus and travelled together down that narrow corridor of land so that now, for the only time each year, they form dense flocks." "Below, on the mud of Panama Bay, the sandpipers are feeding." "This, at last, is the end of theirjourney." "The mud here will never freeze, the sea will enrich it daily, and each bird returns every year to exactly the same patch." "The raptors rise once more in an immense vortex." "From here they willtake their separate ways all over South America, some going as far south as Argentina." "Only by dispersing widely will each bird find enough prey to sustain itself." "The dickcissels have also travelled down the Isthmus of Panama." "They too have come from all over North America and have been funnelled together into flocks of gigantic size and density." "This surely is the very acme of flying skill." "How they co-ordinate their flight in these extraordinary concentrations, changing direction within it, as if with one mind, is one of the unsolved mysteries of ornithology." "Years ago, they, like the hawks and eagles, would have travelled on south from here and spread over the plains of northern South America to feed on the seeds of wild grasses." "But here in Venezuela, they find great fields of cultivated grain, exactly like they found up in the north." "So they have no need to disperse, but remain together and devastate the crops wherever they settle." "It seems they positively prefer one another's company." "Some of the flocks may be half a million strong." "And man's practice of intensive cultivation allows them to stay and feed together." "At night they select a relatively small patch within a huge field of sugar cane where the whole half million roost, half a dozen birds to a single stem." "Flying, when all is said and done, takes a great deal of energy." "So birds have huge appetites and have to spend much of their lives in an unending search for food to fueltheir expensive lifestyle." "Just how they find it, we will be looking at in the next programme in The Life of Birds." "If you travel by air, it's very important to keep your weight down to a minimum." "You can't afford to carry a lot of fuel around, and what you do carry should be energy-packed and not too bulky." "Oak trees put just such a substance into their acorns." "It's there to fuelthe growth of their seedlings, and they protect it with a hard shell, but jays know how to dealwith that." "A beak is itself a concession to weight-saving." "It's much lighter than the jaws and teeth that reptiles and mammals use to process their food, yet it's also very efficient and versatile." "A jay using its beak like a pick can cut through an acorn's armour without any difficulty." "Beaks are closely matched to diet." "A goldfinch uses its beak like a pair of tweezers." "It's just the right length for extracting the seeds from between a teasel's spines." "A blue tit, on the other hand, has a stubbier beak." "That gives it the strength to crack small seeds, but it also prevents its owner from getting them from a teasel." "A greenfinch's beak is even stouter and stronger, but it's far from clumsy." "Watch how, with the help from its tongue, the bird delicately removes the outer shell of these rosehip seeds." "The strongest beak in the finch family belongs to the hawfinch." "That can even dealwith the cherry-stone." "But the bird doesn't simply rely on brute force." "First, it manoeuvres the cherry-stone into the right position for easy cracking." "It gets rid of the broken shell... ..and now it starts the fiddly operation of removing the husk that covers the kernel." "Pine trees, these are in California, protect their seeds by enclosing them in cones." "When they're still green, the seeds developing within are beyond the reach of most birds." "But the cross-bill has special equipment." "It's the only finch that can twist its upper and lower bill in opposite directions." "Now, right at the bottom, it can feel the soft young seed with its tongue." "Got it!" "After a meal of pine seeds, these American cross-bills regularly fly off to a bank of exposed clay." "They're in need of digestive tablets." "Green pine cones are resinous, and resin may cause stomach upsets, but clay in the stomach will absorb the resin and so prevent any trouble." "A crossed bill, however, is not the best implement for digging." "You have to twist your head to one side to get the point into the ground." "But the birds seem to manage to get a sufficiently effective dose to allow them to take daily meals from the pine trees." "Seeds in the temperate parts of the world, however, whether they are in pine cones, cherry-stones or acorns, all have a major disadvantage as a food for birds - they're very seasonal." "In spring and in summer there's none, and then in the autumn there's a glut." "A single oak tree like this can produce 90,000 acorns in a season." "But there are lots of things apart from birds that eat acorns." "Squirrels do, for a start, so if a jay is to collect acorns in the autumn, it will have to do so quickly, before others grab them all." "It is carrying one in its beak, because its crop is full, as you can see from that bulge on its throat." "There can be as many as nine acorns in there." "But what is a jay going to do with such quantities?" "It can't eat them all." "They store them - by burial." "One jay, in a month, may bury as many as 3,000 acorns." "What is more, when winter comes and it's in need of food, it will remember exactly where most of them are." "In North America, oaks stillform huge forests and they produce acorns on an astronomical scale." "Among those that harvest them are woodpeckers." "A woodpecker's beak is a drill, and a very efficient one, so it's not surprising that it stores acorns by drilling." "There are as many as 60,000 acorns stored in the holes drilled in this one tree." "Allthe members of this woodpecker family, eight birds in all, use this one tree." "To start with, the birds deposit newly gathered acorns in a hole to allow them to dry off." "Then, when they have shrunk as much as they are going to do immediately, they're given individual storage." "This larder provides food for the family throughout the year, but the birds have to be very vigilant and ready at alltimes to repel raiders." "There's also a lot of maintenance work to be done." "As the acorns continue to dry and shrink, they become loose in their sockets." "That would never do." "They would be easy for someone to steal." "They might even drop out." "On the other hand, if they are hammered into a hole that is too tight, the shell could crack and then the acorn would rot." "So maintenance is a never-ending, year-round labour, and it takes a lot of care and judgement." "The result is a great acorn treasury that will last the whole family well into the next harvest." "These neat holes are made, not for storage, but for theft." "They're cut by another kind of woodpecker - a sap-sucker." "They're just deep enough to tap the vessels along which the tree transports its sap, and sap is largely what the sap-sucker lives on." "The bird cuts its sap-wells with an accuracy and symmetry that would do credit to the finest cabinet-maker." "Sap normally hardens quickly and seals a wound." "This doesn't." "It could be that the sap-sucker produces an anti-coagulant in its spittle, but if it does, no one yet has managed to identify it." "Even so, each little well eventually runs dry and the bird has to cut another." "These wells have been made in the trunk of a pine tree which produces sap throughout the year." "Other trees, such as these aspens, only produce sap in quantity in spring and summer." "When the sap-sucker moves on to these, it cuts differently shaped wells." "With this spring increase in the sap supply, new birds appear in the woods." "A yellow-rumped warbler." "They're quick to drink from the wells cut by the sap-suckers." "Food is short so early in the year." "The birches are now in leaf, and the sap-sucker moves on to them, and makes wells of yet a different shape." "A northern oriole - another hungry migrant only too willing to benefit from the labours of others." "And a hummingbird." "It used to be thought that hummers timed their arrival to coincide with the opening of the spring flowers from which to drink nectar." "But they arrive well ahead of that." "Their appointment is with the rising of the sap and the work of the sap-sucker." "Sap is an excellent food - energy rich and easily flicked up with the tongue." "But it can only be collected from many of these northern trees during part of the year." "So when winter approaches, warblers and hummingbirds fly south again to where it's summer allyear long." "Here in Mexico, the sap is taken, not only by birds, but by insects." "The trunks of many of the trees seem to be sprouting long hairs." "At the end of each, there's a tiny drop of liquid." "The hair is a tube projecting from the rear of an insect lying beneath the bark drinking sap." "But the insect gets more sugar than it needs, so it excretes the excess." "And that is what the hummingbirds, with exquisite accuracy, manage to collect." "Many different warblers take it too." "The liquid, rather flatteringly called "honey-dew", is so much sought after that some birds take up residence in a particular tree and will drive away any others that try to feed there." "Their meals, however, come in such small instalments that feeding has to be almost continuous." "It takes about an hour for a drop to accumulate at the end of a tube, so to get enough to sustain themselves, the hummingbirds have to travelfrom one to another on a regular round throughout the day." "Plants produce other edible things as well as seeds and fruit and sap." "They sprout leaves, but in truth leaves are not very good food." "They're very bulky and need a lot of digesting." "So animals that live on leaves, like these cows, for example, tend to be rather hefty creatures with massive batteries of grinding teeth and special capacious stomachs." "Cows, having grazed, lie down and bring up each mouthfulfor a second grinding chew." "No bird does that - you can't chew with a beak." "Geese have to use a different technique." "They're big birds, as they have to be to accommodate such bulky meals." "But instead of digesting the grass intensively, they eat a very great deal of it and get rid of what they can't digest almost immediately." "The appetite of geese is apparently never-ending, and a flock of them, like these barnacles, willwork its way across a meadow nibbling non-stop with almost feverish speed." "And pooping allthe way." "It makes a terrible mess, but it does mean that after feeding for several hours... ..the geese are not weighed down by great quantities of undigested grass..." "..and can get into the air without much difficulty." "In South Africa there's a rather smaller leaf-eater - the mousebird." "They do make some attempt to digest their meals a little more thoroughly." "They start feeding early in the morning." "Then, with as much nibbled leaves on board as they can manage, they sit for hours on end with their distended stomachs turned towards the sun, so that its warmth helps with their digestion." "You can't beat a siesta after a heavy meal." "In allthe bird kingdom, there's only one species that is really specialised for leaf-eating." "This is it - the hoatzin of South America." "Like a cow it has two compartments to its stomach, the second of which is full of bacteria that help ferment its meals." "In consequence it's a bulky bird and positively clumsy in the air." "More a lumbering cargo plane than a superjet." "Birds, by stripping leaves, eating seeds and drinking sap are exploiting plants - stealing from them." "But many plants exploit birds by using them as couriers." "The arrangement is such an ancient one that both employers and employees have evolved specialways of transacting their business." "The plants attract their couriers with flowers." "They pay them with nectar, which is easy and cheap to produce, because it's no more than water and sugar and that's what I've got in here." "And these Australian rainbow lorikeets love it." "Here in Australia there are some plants that are in flower throughout the year, so it's possible for birds to specialise as nectar feeders, as these lorikeets do." "Their tongues, instead of being hard and leathery, have a feathery brushy tip so they can lap up the nectar." "And the plants, when they have a need for a messenger, advertise the fact by producing flowers with particularly bright petals." "Having collected allthe nectar immediately available on one tree, the lorikeets move off in a flock to feed at another, carrying the pollen they collected with them." "But they take nectar from many different kinds of flowers, and if, as here, the plant they next visit happens to be a different one the pollen they're carrying will be wasted." "The plants way of reducing that risk is to recruit an exclusive service with couriers who, during their flowering season, willvisit them alone." "Here in South Africa, this species of heather encloses its nectar in a "floral safe"" "which only a particularly shaped beak can unlock." "This orange-breasted sunbird has a beak of that shape, but even so, it has to probe really deeply to reach the heather's nectar." "And every time it does, it triggers a little explosion of pollen." "When the bird drinks at another heather plant, some of that pollen will be brushed off and the heather will have achieved its end." "But bird and flower can fit one another more closely than that." "On Mount Kenya, there's a sunbird with an even more strongly curved biall" "The golden-winged sunbird." "And this is its employer - the lion's claw flower." "The feathers on the sunbird's head look golden, like those on its wings." "But not so - they're black." "The gold colour is entirely due to pollen which is stamped on it when the bird thrusts deeply into the flower." "The devices used by plants to restrict their payments to their employees may, if taken to extremes, defeat the object of the exercise." "This South American plant has gone, literally, to great lengths to shield its nectar from all but its established partner, and that has encouraged burglary." "This is the black flower-piercer." "It knows exactly where the nectar is stored, and it knows a quick way of getting it, too." "Its tongue is flicking into the nectary at the top of the flower's trumpet so that nectar is channelled down its lower bill into its throat." "The datura has even longer flower trumpets, but they are robbed just as easily." "Here in South America, hummingbirds are the main collectors of nectar, and they will collect it any way they can." "Using a break-in by a flower-piercer is as good a way as any other, as far as they're concerned." "The trumpet of the datura flower is so long that you might think that nothing could drink from it - legally, as it were." "And only one bird can - the sword-billed hummer, which has the longest beak in relation to its body of any bird in the world." "A plant only flowers for a short period each year, so a nectar drinker has to have a succession of suppliers." "A sword-bill also drinks from passion-flowers." "The South American climate is so equable and the number of plant species so huge that there are always some flowers to be found." "Accordingly, hummingbirds have evolved highly specialised equipment for nectar feeding." "They have developed a unique way of flying that allows them to hang stationary in the air while they drink from a dangling blossom." "Their tongues have become threads that flick in and out a dozen times a second, but they're virtually useless for collecting any other kind of food." "Where most plants tend to bloom at the same time of the year, neither the suppliers nor the drinkers of nectar can be so specialised." "So the coraltree, blooming in Thailand, has no alternative but to be generous and offer its nectar in a free and open way." "This delectable seasonaltreat attracts all kinds of birds from far and wide." "Such a large and varied clientele is pretty well bound to do the job required of them." "After they are pollinated, plants produce seeds and then many engage other birds to distribute them." "That, by and large, is heavier work, and the payments they offer for that are made with a different currency - fruit." "Hornbills are on their way to do a job for a fig tree in the Indonesian rain forest." "In northern Europe and America, waxwings gorge themselves on autumn berries." "A plant wraps its seeds in the minimum flesh needed to persuade the bird to swallow them." "These berries have so little that it's quickly stripped off in the waxwing's stomach, and then the waxwing can get rid of the indigestible seed." "The story is the same all over the world." "In New Zealand, kokakos are great berry eaters and distribute the seeds of many of the plants of their native forest." "In South America, tiny wild avocados are the specialfavourite of one of the most dazzling of birds - the quetzal." "The avocados may be small, but they're still too big for the quetzalto swallow." "So the stones are ejected, not from the back end, but from the front." "The bird has had a good meal, and the avocado has had some of its seeds carried to a new site." "There are other things for birds to eat in a forest apart from the products of plants." "They may be difficult to find;" "they may be even more difficult to catch, but they're wellworth having because they're full of nutrition." "Things, for example, like this." "The morpho - a big and powerful butterfly." "A jacamar - a cousin of the kingfisher's." "A butterfly's wings aren't very digestible and have to be stripped off before the bird can swallow the fat, nutritious body." "Winged termites erupting from their holes in the ground and flying away to establish new colonies." "A whole host of birds relish these." "Ants are trickier meals." "They, after all, can sting." "It takes a specialist to dealwith them." "This is the rufous woodpecker of Southern India." "Its beak is just as efficient at demolishing an ant's nest as it is at drilling into wood, and the bird seems totally indifferent to the ants' sting." "The feathers of its tail, like those of allwoodpeckers, are particularly stiff so that they can serve as a prop." "The most nutritious morsels are the soft, fat, stingless grubs that can be found in the very centre of the nest." "Insects are almost everywhere on every tree;" "on twigs, in buds, crawling around in crevices of the bark, and many birds find quite enough to sustain themselves just by looking carefully." "But some work harder - and get greater rewards." "The nuthatch, in European woods, is indefatigable." "It will eat many things, including seeds during the autumn and winter, which it can crack with its workman-like beak, but in summer, insects are a major part of its diet and its beak serves equally well for picking them out of the bark." "The greater spotted woodpecker is a little more specialised." "It particularly likes the grubs of wood-boring beetles, and the first thing to do to find them is to chisel away the bark." "Its tongue extends for an inch and a half beyond its beak and has a harpoon at its tip." "When that hits a grub fair and square, it sticks." "Tree-boring insects are never safe when woodpeckers are around." "But woodpeckers never got to the Galapagos, far away from anywhere in the Pacific." "Insects did though, and their grubs bore into trees here, just as they do everywhere else." "But no Galapagos birds have the physical adaptations with which to reach them." "Galapagos finches, however, are both intelligent and ingenious." "Their beaks are perfectly adequate for stripping away bark." "There's a grub under there somewhere - it can hear it." "But how, without the long tongue of a woodpecker, can it get it out?" "It needs a tool - a spine from a cactus." "A success - but only a partial one." "It has only extracted little bits of the grub." "Nearby, a bird from another clan of finches uses a slightly different technique." "It selects a rather stouter toolthat can be used, not so much for stabbing as for levering." "That has shifted the grub a little nearer the hole." "It's not quite within reach, but it's still got that lever handy." "Give it another go." "And that's got the rest of it." "Another remote and isolated island, on the other side of the Pacific" " New Caledonia." "It gets a lot of rain and so it has a much bigger and richer forest than the Galapagos." "But it's so far from any of the major continents that woodpeckers have not got here either." "This fallen tree-trunk is studded with holes;" "the work of wood-boring beetles." "Their size suggests that they're made by much bigger insects than their equivalent on the Galapagos." "The New Caledonian crow - and crows are among the most intelligent of birds." "Once again, the sound of a grub gnawing away in its burrow betrays its presence." "And once again, since this grub-hunter hasn't got the long tongue of a woodpecker, a tool is needed." "To contact this grub, the stick will have to be thrust in really deeply." "A spectacular catch!" "Some of these crows become so attached to one particular toolthat they carry it about with them." "This log is clearly a good source of grubs and a whole group of crows have come here to feed." "Their technique is neither to stab nor to harpoon, but something more subtle - to irritate." "This grub has got big jaws and, if attacked, it can give a powerful bite." "And that's what the crows rely on." "A younger bird joins an experienced adult to see how things are done." "Now the pupil has a chance." "It hasn't got allthe details exactly right." "It will be about a year before it masters the skill." "There are insect grubs everywhere, of course." "The only problem for insect-eating birds is getting at them." "But sometimes other creatures are of help." "You might think that this is a recent partnership, but I'll bet when our prehistoric ancestors first dug for tubers and planted seeds in Europe one of these little robins appeared within a couple of days." "Other animals must have done the same job for them before human beings did." "Once, not so long ago, wild pig were common all over Europe, and they're great diggers and rootlers." "So maybe the robin's boldness and friendliness with other kinds of animals started in prehistory, even before human beings arrived in Europe." "Such partnerships exist all over the world - even in the most unlikely places." "This little bird lives on a small island in the Indian Ocean, one of the Seychelles:" "so small and so isolated that few mammals got here before human beings." "It's not closely related to the European robin, but it behaves just like one." "When Europeans first came to the Seychelles and saw it, they called it a robin because of its similar habits." "But what partner did it have before human beings came along?" "Could it be this?" "Once there was a large population of these giant tortoises on several islands in the Seychelles." "They weigh several hundredweight and those huge legs dig into the ground with every step." "There we are!" "These little birds, now even rarer than the tortoises themselves, are stilltheir regular companions as they plod around the island." "A swamp in South America." "An abundance of water and a warm tropical sun make it a paradise for insects of all kinds." "A kind of fly-catcher - a cattle tyrant, and another obliging partner - a capybara, a large semi-aquatic rodent." "As the capybara moves around it inevitably disturbs insects of some kind or another, and what better place for an insect-eater to spot them than sitting on the back of one." "Would the view be any better from there?" "Perhaps it would be." "A few of these partnerships between birds and other kinds of animals have become very intimate indeed." "The hide of a hippo may not seem a particularly rich source of insects, but there are little ticks to be had in the various cracks and crannies, and ox-peckers go there to search for them." "They have extremely sharp claws, with two toes pointing forwards and two backwards, so that they can cling at any angle - even on a slippery hippo." "Land animals with hair on their hide are likely to be more productive ground." "Ox-peckers pay particular attention to their ears." "That's the sort of place where you find ticks." "And if there is one, the ox-pecker will remove it." "And they also eat earwax." "Dandruff is another part of their diet." "Their beaks are flattened so that, with their head held sideways, they can comb through their hosts' hair." "Ox-peckers spend alltheir life on, or closely beside, their animal hosts." "They court and mate on their backs." "And when they fly off to make a nest, as they must do, they pluck hair from their hosts' backs with which to line it." "But do they do anything in return?" "They remove irritating, even damaging, insects that their hosts can't dislodge for themselves." "But the bird's main diet is blood." "Sometimes they get it by swallowing ticks that are bloated with blood." "But they also take it directly, pecking at an animal's wounds to keep them open." "When their hosts get irritated, they go back to their toiletry duties, before once again snatching a sip." "So, in spite of having such a specialised life, living on the bodies of mammals, ox-peckers manage to get quite a varied diet." "A maggot here, a tick there, a little sip of blood, perhaps a little tasty earwax." "But there are some birds that literally live on mammals - alive or dead." "They eat them; and those are the birds we'll be looking at in the next programme in this series." "Birds are the most accomplished aeronauts the world has ever seen." "They fly high and low." "At great speed and very slowly." "And always with extraordinary precision and control." "But birds are not the only creatures in the air." "There are also smallfurry mammals, bats, like these in Texas." "They are so competent in the air that they have just made a journey from Mexico, a thousand miles away, simply in order to rear their young in this cave, which is particularly suitable for them as a nursery." "Just now they are flying out to catch their evening meal of insects." "But they had better be careful, because in the skies above them there lurks a creature that can outfly them." "It is, of course, a bird." "A red-tailed hawk." "Bats with their fluttering zig-zag flight are not easy targets, and a hawk needs all its aerobatics skills and powers of concentration if it is to snatch one out of the confusing multitude." "That is one bat that will not return to the roost tonight." "The red-tail lives beside the cave and is well practised in bat-catching." "This prairie falcon, on the other hand, is a visitor, but it's learning fast." "Unlike the hawk, it chooses to eat its meals on the wing." "Bats are latecomers to the skies." "They've only been flying for a mere 60 million years." "The air was first colonised 200 million years earlier still by the insects, but now they can't escape the birds either." "Some insects, of course, have powerfulweapons with which to defend themselves." "But a bee-eater certainly knows how to dealwith a bee." "A rub against the perch usually discharges the sting." "And if that doesn't, then a sharp nip will squirt the venom harmlessly into the air." "Dragonflies first flew around 350 million years ago and insects had the skies to themselves for 150 million years thereafter." "And then a different kind of animal joined them in the air." "As the dinosaurs dominated the land, so the pterosaurs now ruled the skies." "Pterosaurs had wings of skin, stretched between one enormously elongated finger and their flanks." "They flew over the sea as well as the land." "It seems likely that some roosted on cliffs and launched themselves into the air as gannets do today." "They probably snatched fish from the surface of the sea, and some certainly fell into it." "Their bodies were buried by mud;" "the mud turned to limestone and eventually became exposed in great quarries like this one in Southern Germany." "Today, separating the layers of sediment is just like searching through the pages of a visitor's book that hasn't been opened for 150 million years." "Of course, nearly all of the pages are absolutely blank." "Visitors, after all, were very few." "But every now and again you come across a signature that is unmistakable." "A fish the size of a sardine." "A shrimp, even its antennae perfectly preserved." "One of those pioneering dragonflies, nearly six inches across." "And a pterosaur with skinny wings and teeth in its jaws." "With so many superb fossils, people thought that they had a complete list of the visitors to the lagoon." "And then, in the middle of the last century, a signature was discovered that was wholly unexpected and totally amazing." "This is it." "It's a feather." "Its barbs are narrower on one side of the quill, just as they are on the feathers of a modern bird's wing." "This asymmetry is a sure sign that such feathers were used for flight." "But what animal at the time of the dinosaurs could have such a wing?" "The answer was found the very next year in the same quarry:" "a fossilwith its feathers still attached to its body." "This is archaeopteryx." "It had three toes armed with claws and long, strong legs." "Clearly it walked and perched like a bird." "But its head was very reptilian with bony jaws." "And in those jaws, teeth." "Its spine was extended into a bony tail, again like that of a reptile." "But on either side of the tail bones, clearly visible, it had those characteristic possessions of birds:" "feathers." "Feathers are made of keratin, as are the scales that many birds still have on their legs, and reptiles all over their body." "A scaly coat must be very hot, so reptiles, like this skink, have to seek shade during the hottest part of the day." "But if the scales became fibrous, they could be fluffed up to let in cooling air during the day, and closed down to trap insulating air for warmth at night." "So it is not difficult to believe that scales eventually became transformed into feathers." "But why should they have become so long that they enabled the animalto take to the air?" "Well, this Australian lizard suggests an answer." "When it is threatened by its enemies, it responds by spreading the great frill it has around its neck." "But if that doesn't scare them off, it runs away, on its hind legs." "If such a reptile had developed feathery scales on its forelegs and then spread them out then it might easily lift into the air and so escape a land-bound predator." "There's another possibility." "Maybe that early reptile did not live on the ground but climbed in the trees searching for food, as today the little flying lizard of Borneo does." "It now glides from tree to tree." "It has developed wings that are flaps of skin supported by elongated ribs." "If that early enterprising reptile with feathery scales did have specially long ones on its arms, then they too would have enabled it to glide from tree to tree." "Maybe its arm muscles were even strong enough to allow it to make a few flaps to help it on its way." "Archaeopteryx was certainly well-equipped for climbing, for its wings still carried three fingers, each ending with a hooked claw, idealfor clinging on to twigs." "And there are birds today with very similar ones that give a clear hint as to how it might have used them." "These are young hoatzin, sitting on their nest in a South American swamp, still guarded by their parents." "A hoatzin chick has an adventurous disposition and starts clambering about when it's only a few days old." "The hooks on its front limbs are obviously very useful in keeping it secure until such a time as they become feathered and reliable wings." "One can imagine that archaeopteryx used them in much the same way and for much the same reason." "Sometimes, however, there's a disaster." "There are dangerous reptiles in the swamp:" "snakes and caiman." "But those claws on the wings are once again invaluable." "Mother returns." "She has been feeding on leaves and will have a full crop." "Maybe there will be some for the chick." "The hoatzin, of course, like all modern birds, doesn't have bony jaws with teeth like archaeopteryx, but a lightweight beak." "When did that important change take place?" "Well, this fossilised bird has a beak, and it was found in China recently." "It's only a little younger than archaeopteryx, so it seems that the change took place quickly." "And it must have made flight much more efficient for it prevented a bird from being nose-heavy and significantly reduced its overallweight." "By 50 million years ago, the dynasty of birds was firmly established." "At that time, a great lake lay here in Central Germany." "It's long since dried out, and the layers of mud from its floor have turned into shales." "Excavations like the one that's going on here have revealed just how varied the birds had become." "This one has been set in yellow resin to make its details quite clear." "It had a horny beak, a fully feathered wing, a long feathered tail with no bony support and long legs." "It probably looked like a rail." "Other fossils from these shales show that several families of modern birds were already established." "This was a water bird, possibly an ancestor of today's jacana." "It would have found plenty of insects among the floating leaves on the lake." "There were birds with powerful chisel-like bills, perhaps woodpeckers, that even in this early period had started excavating insects from trees nearby." "Another inhabitant of those prehistoric woods had a stubbier, more all-purpose beak, rather like finches do today." "There were tall birds with long powerful legs that hunted for small reptiles on the ground as the South American seriama does." "And there was a gigantic vulture with a wingspan of over 20 feet, bigger even than that of the Andean condor and probably the biggest flying bird that has ever existed." "There were even birds which, judging from their skeletons, were as agile in the air as their probable descendants, the frigate birds." "So by 50 million years ago, severalfamilies of modern birds were well established." "The rule of the reptiles was now really over." "Not only had pterosaurs disappeared from the skies, dinosaurs had gone from the ground." "So the dominance of the land was up for grabs." "There were two contenders:" "the mammals and the birds." "The biggest mammalto be found from this lake in Germany was a primitive horse." "It was no bigger than a spaniel." "But the biggest bird was very different." "That was the lower part of its beak, and this was the upper." "If its skeleton still lay here, you would have to dig a huge pit to extract it." "This bird was immense." "It has been named, with good reason, the terror bird." "Its wings were tiny but it had long and powerful legs." "Flightless birds of a comparable size still exist and can give us some idea of what it looked like." "This, the ostrich, is the biggest and heaviest bird alive today." "It is probably not closely related to those monstrous feathered hunters of prehistory, but together with the emu of Australia and the rhea of South America, it belongs to a very ancient family of birds that abandoned flight a very long time ago." "It relies for its defence on speed and, in the interests of its efficiency as a runner, its toes have been reduced to two." "If pursued, it can sprint at over 40 miles an hour." "But although it is now flightless, it still has many of the physical characters evolved by its ancestors that enabled them to fly." "It still has feathers and they are still placed on its wings in much the same position as those on the wings of a flying bird." "But they are now useless for flight." "Their filaments have lost their hooks so they can no longer be zipped together into an unbroken blade." "Instead they are loose and fluffy." "Their only function now is as insulating blankets, to keep out the cold at night and the heat during the day." "Ostriches have become grazers, the bird equivalent of antelope or horses." "But unlike them, they not only pick up leaves." "They swallow all kinds of other things as well, and for a very good reason." "Just as they inherited feathers from their flying ancestors, so they also inherited a lightweight, horny beak instead of a heavy jaw laden with teeth." "And without teeth, they need another way to grind up their food." "A pebble can help them do just that." "Down it goes into a muscular compartment of the stomach, the gizzard, a kind of millwhere bits of vegetation are churned around and ground into a digestible pulp." "But while some birds were abandoning flight, some mammals were becoming formidable hunters." "Ostriches with their superb eyesight and tall necks are able to keep a sharp lookout for approaching danger." "The cheetah has to calculate very carefully whether it's worthwhile chasing something... ..and an ostrich, usually, is not." "It is so very fast, and even if it's caught, it has little meat on it compared with a similar sized mammal." "But birds that can't run are a tempting target for hunters everywhere." "If they couldn't fly, they wouldn't last long." "Flight has certainly enabled birds to colonise the entire globe." "But the compulsion that drove them into the air in the first place, and has certainly kept most of them there ever since, was probably safety." "Even so, the cost of flying is high." "Flapping wings takes a lot of effort and if there is no need to do so, birds save their energies." "Those that live here on the Galapagos Islands, isolated in the Pacific, have no natural enemies from which to escape, so some birds don't bother to fly." "Have a look at these cormorants, for example." "At first sight, they look like many another cormorant sitting on cliffs round the world." "But these wings are stunted and tattered." "This bird could never get into the air." "Its feathers now serve only to keep it warm in the water." "It's for that reason alone that it keeps them well-oiled." "It is scarcely any better at walking than it is at flying." "Once in the water, however, it's a very efficient mover indeed." "The position of its legs right at the back of its body that made it so clumsy on land is idealfor propelling it through the water at speed and helps it to catch allthe fish it needs." "For the Galapagos cormorant, flight has become an irrelevance." "Other island birds have reacted in a similar way." "This is New Caledonia in the western Pacific, and this is its special bird, the kagu." "Its ancestors must certainly have arrived here by air, but since New Caledonia had no ground predators until recently, they gave up flying and today the kagu is virtually flightless." "It finds all its food on the ground in the leaf litter." "It's been here so long that it's difficult to be sure exactly who its ancestors were, but they were probably herons." "Rails are a very widespread family of birds." "Wherever there is a big swamp, you are likely to find one." "On the continents, they tend to lurk shyly in the undergrowth to keep out of trouble." "But some, somehow, have also managed to reach a great number of islands and there they seem to have no fear at all." "This one, it's a weka, has also become flightless because of its isolation on an island." "But its island is immense." "It's 1,000 miles long, if you discount a narrow arm of sea that crosses it in the middle, and it contains mountains over 12,000 feet high;" "it's New Zealand." "The first land-living mammals to get here were human beings and they didn't arrive until a mere 1500 years ago." "So here you can still glimpse what the world would have been like if the birds had won that battle with the early mammals and now ruled the earth, for here they once did." "Many of New Zealand's birds flew here from Australia, 15,000 miles away across the sea to the west." "They started to do so millions of years ago, and they are still doing so today." "So if you know Australian birds, you will recognise quite a lot, particularly those that are relatively recent arrivals." "The New Zealand pigeon is not allthat much different from Australian ones." "The saddleback, on the other hand, must have been established here for much longer for it has changed so much that no one is quite sure what family it belongs to." "The tui has similarly mysterious origins." "No other bird has a costume to compare with its lacy cape and that little white throat bobble." "The kaka is clearly a parrot." "There are lots of parrots in Australia so it's not surprising that some of them in the past should have found their way here." "Most of these birds have still not learned that mammals are dangerous." "This saddleback is a fully wild bird and certainly hasn't seen me before." "But look how trusting it is." "This is a New Zealand robin." "It's no relation to the European robin and, if anything, it's even braver." "The New Zealand bush is full of food, of one kind or another." "And as the birds once had it alito themselves, some were able to adopt diets and ways of life that elsewhere were claimed by mammals." "The kokako eats much the same thing as squirrels: fruit and leaves and insects." "European squirrels run along the branches." "Asian squirrels, using a skinny parachute stretched between their legs, are able to glide as well." "And that is very much how the kokako gets around in the trees." "Having glided down to the lower branches, it runs back up them and jumps from one to the other." "So if the kokako, up in the trees, feeds in the same way as a squirrel might do, what lives and feeds like a mammal on the ground?" "The leaf litter in these forests is full of food of one kind or another." "There are earthworms and insects and beetle larvae." "In any other land there would be some small native mammal that was burrowing around seeking that food." "But not here in New Zealand." "Here there's something quite different." "You will only see it after dark." "It is, of course, a bird, but what an extraordinary one." "The kiwi." "It's territorial and calls stridently to proclaim its ownership." "It finds its prey by smell, uniquely its nostrils are on the tip of its beak." "It's found a worm." "But once it drops it, its eyesight is so poor that it can't see it and it has to smellfor it, with its beak." "Its tiny vestigialwings are invisible, buried in its plumage and it has lost all sign of a tail." "If the kiwis live in a patch of forest close by the sea, then in the evening they may come down on to the beach to look for these:" "Sandhoppers." "They love them." "And that will give us a chance, a rare chance, to see them out in the open." "To do so properly, we have to use our special starlight camera." "The kiwi is hunting along the strand line where there are lots of hoppers feeding on the decaying seaweed." "Its sense of smell is so acute it can pick out the largest juiciest hoppers deep in the sand without even seeing them." "Our starlight camera can see much better than I can." "I need a torch to see this extraordinary creature properly, but it doesn't seem to mind." "Its feathers are just filaments, so that it almost looks as though it is covered with coarse fur." "Probing sand with your nostrils is allvery well, but it does clog them up, and so you need to blow them clear every now and then." "It's nocturnal and furry:" "It finds its way around by smell." "It lives in holes and digs for worms and grubs." "It's a bird equivalent of a badger." "But there's plenty of other food to be found in the New Zealand bush." "Here on the forest floor, there are lots of leaves." "They may be a bit twiggy and coarse but they are food nonetheless." "What could have browsed on these?" "Well, not far from here, bones like this have been dug up." "It's obviously a leg-bone, and at first sight you might think it was a leg-bone of a mammal, say perhaps, a cow." "But when you look at it closely you can see that it's got a honeycomb structure." "It's a bird bone, but the bone of a very big bird indeed, as we know from the rest of its skeleton." "It had just three toes." "Its pelvis and its spine lead up to an extraordinarily long neck." "This bird stood over six feet, two metres tall." "The first human settlers on these islands saw these giants alive and called them moas." "Among them were the tallest birds that ever existed, that weighed over 200 kilos, 400lbs." "There were about a dozen different species of varying size and weight." "Up on the high moorlands, there were smaller species with thicker feathers to keep them warm." "The absence of mammals didn't mean that the moas had no enemies." "They were hunted by, of course, another bird." "An immense eagle that could manoeuvre through the patchy forest." "The only prey that was abundant enough to sustain such a giant were other birds and it's probable that it was able to tackle even the biggest moa." "Its talons were certainly long enough to stab right through a moa's flesh and into its pelvis, as some of the bones show." "Nevertheless, the moas survived for a million years or more and spread all over New Zealand." "But eventually mammals did reach these remote islands." "Apart from bats which flew here, the first to arrive were those most dangerous of all, human beings." "They hunted the moas for meat and soon they had hunted them to extinction." "But a different kind of flightless bird does still survive, up in these high mountains." "Like so many of New Zealand's native birds that had abandoned flight, it had no defence against the alien mammals that Europeans brought with them and that soon escaped and ran wild." "Rats ate their eggs and killed the chicks, and cats and stoats massacred the adults." "There was a giant flightless coot that was originally very common." "But it got scarcer and scarcer and by the middle of the nineteenth century, it was thought to be totally extinct." "And then, just 50 years ago, someone in these remote valleys found something like this." "This is the dropping of a takahe and here, the severed stems of tussock grass on which it's been feeding." "It's still here." "And here is her nest." "She's sitting tight, hiding her brilliant red bill so that she is not conspicuous." "Indeed, when only her lovely moss-green back is visible, she is well camouflaged from her only native enemy, a bird of prey, circling overhead." "Only about forty pairs of takahe survive today in the wild." "So the eggs she is sitting on are very precious." "This high country was probably not the takahe's original home." "Most of the population in the last century lived at lower altitudes and there they had lush vegetation to feed on in the warm swamps." "But most of those were drained and turned into farmland." "So now these high empty valleys, only recently scraped down to the rock by glaciers, are the takahe's last refuge and there is little to eat up here, except tussock grass." "Extracting something nutritious from tussock is not easy." "The takahe's technique is to pull up a whole stem and then nibble just the bottom inch or so." "That's where most minerals and sugars are and it's the only bit tender enough to be easily cut." "At first the chick doesn't know how to do this and has to be fed." "It will stay with its parent for a whole year." "Only then will it be strong enough and skilled enough to feed entirely by itself." "Now it's summer, but when winter comes, life will be even tougher." "Then the pools freeze over and the tussock has no fresh shoots, even if they could be reached beneath the snow." "Then the takahe is reduced to digging for tubers in the freezing earth." "So the birds' continued survival up in these barren moorlands is by no means assured." "One other flightless bird found refuge from mammals in these high mountains;" "and in many ways, it was the most extraordinary of all." "It was a giant parrot, the kakapo." "It lived in very much the same way as rabbits do." "It created tracks through its territory generation after generation, trudging along here and feeding by plucking these grasses and eating the succulent base." "This particular path runs under this bush and continues upwards along the highest edge of this narrow ridge." "The track leads to this shallow bowl, and there are others like it spaced out along the track." "They were excavated by the male kakapo whose territory this was." "He would dig them out;" "and then in the night, he would come here and, crouching low, make a deep booming call which echoed out across these valleys, summoning the females to come to him." "But there were no females seen after the 1970s up here." "One lone male continued trudging up here and calling." "But in vain." "And in 1985, his callwas heard no more." "And then when hope was almost gone, a new population of kakapos was discovered on the southernmost island, Stewart Island." "They too were being harried by cats and stoats, so the survivors were caught and taken to three small cat-free islets." "There were only 61 of them." "The kakapo's survivalwas on a knife-edge." "A male, after slumbering all day in his burrow, emerges for his evening meal." "His hearing is acute, he listens for danger." "He's following his regular track that will lead him to the highest slopes of his mountain." "A female has clambered up into the top of the bushes, looking for fresh shoots and fruit." "Her dappled green plumage camouflages her against attacks from falcons, but even so, she won't dare to venture into the topmost branches until it's dark." "Nightfall, and now we need our starlight camera to see what's happening." "By midnight the male has plodded his way right to the summit of his mountain." "He has reached one of his bowls from which his calls could echo out over the valley below." "He begins to tidy it up." "The female has found what she wants up in the branches." "She will need allthe most nourishing food she can find if she is to produce an egg." "Even at the best of times, she will not be able to accumulate enough bodily reserves to lay every year." "The male begins to inflate air-sacs on his chest that will act as resonators and so amplify his calls, sending them booming out across the valley." "There are probably only 12 fertile female kakapos left alive." "In the first 10 years after they were moved to the safety of their new homes, only three chicks were reared." "But then in the last two seasons, seven young kakapo were successfully hatched." "Maybe the species will come back from the brink of extinction after all." "Of course, only a minority of New Zealand's birds have become flightless." "Most, like these handsome spotted shags, have retained that characteristic talent of birds, the ability to travel by air, and worldwide, birds have exploited that ability to an extraordinary degree." "Some can make journeys of over a thousand miles without coming down to earth." "Some can fly to altitudes of over 25,000 feet." "Some can even fly backwards." "How they manage to get into the air and sustain themselves there is what we will be looking at in the next programme." "Sparrows in South Africa." "Like all sparrows, they eat pretty well anything;" "insects, fruit and particularly seeds." "They convert that diet into their own flesh, which is the richest of allfoods: meat." "So they themselves are much hunted." "A falcon is also looking for a meal." "And it has one." "Meat is such a rich food that a falcon need only kill once a day to sustain itself." "So there's plenty of time for sitting around on the perch." "Nice work if you can get it." "But getting it is not necessarily allthat easy." "This hillside in New Zealand may look bare, but in fact I'm sitting in the middle of an immense, active colony of shearwaters." "The adults at the moment are out at sea fishing, but these are their burrows and inside of almost every one, there is a fat, juicy chick." "And this bird knows it." "This is a parrot, a kea, but not the sort of parrot that is content just with fruit and nuts." "Its beak can certainly cope with such things, but it can also give a bite that kills." "The keas tour the shearwaters' burrows, listening." "They've heard something." "A shearwater chick is moving in its underground nest chamber." "But the tunnel is too narrow for them." "If they want the chick, they will have to dig for it." "Keas became meat-eaters relatively recently and have no special adaptations to help them find their victims." "But other birds took to eating meat much earlier and they have some highly sophisticated ways of locating their targets." "The great grey owl hunts in the Arctic." "In the summer, it scarcely gets dark, but the owl's prey is, in any case, largely invisible for it is hidden beneath the snow." "Like the kea, the owl listens for its victims." "Its hearing is many times more sensitive than the kea's, and ten times better than ours." "The feathered discs on either side of its face act like ear-trumpets." "Each shields the ear on one side from sound coming from the other." "So the owl can scan the landscape in stereo." "It's detected a faint rustle beneath the snow, made by a lemming." "Invisibility was insufficient protection for the lemming." "The great grey owl's hearing enables it to hunt the year round, even through the Arctic winter, when it's dark for weeks on end." "Elsewhere, other owls locate their prey with a different sense: vision." "The bigger an eye, the more light it gathers, so the better it functions at very low light levels." "These eyes are so big that they can't even revolve in their sockets." "They belong to a scops owl." "They are sensitive to shape rather than colour, so a scops owl sees a soot and whitewash world, but a world that most other birds would find impenetrably dark." "Without colour, it's movement that betrays the presence of prey." "A spider." "Quite big enough and succulent enough to provide a snack for a scops." "And that is what it will be if it moves." "Daytime hunters, like these buzzards, have vision of a different kind." "During the breeding season, they feed mainly on young rabbits." "If there is plenty of light, an eye can become virtually a telescope and buzzards can spot a rabbit from over a mile away if it moves." "They also see it in full colour." "With such acute distant vision, a buzzard can keep a great area under constant surveillance without moving from its perch." "Rabbits feeding beside their warren." "They would be unwise to venture far from their holes." "The buzzard has detected a chance and is in the air." "From 300 feet above the ground, it can see each rabbit very clearly." "No luck this time for the buzzard." "The great majority of a buzzard's attacks are failures but the energy spent on an attempt such as this was not great and the wind carries it back aloft." "The kestrel, little more than half the size of the buzzard." "It seeks much smaller prey: voles." "Its colour vision is also excellent, better, indeed, than ours for it spans a greater range of the spectrum extending into the ultraviolet." "So the blue of the sea around the Cornish coast appears much more intense to a kestrel than it does to us." "For a long time, no one could understand how, or indeed if, that might help it to hunt." "Now we're beginning to get clues." "The voles seldom leave the shelter of their tunnels through the grass, at least during the day." "They repeatedly mark their tracks with urine, and urine, in ultraviolet light, is very conspicuous." "So with ultraviolet vision, the kestrel can see the signposts that the voles can only smell." "As a consequence, the kestrel knows just where to focus its attention." "And that was a success." "The open skies above the wide plains of Africa." "Vultures." "They also eat meat, but only that which has been slaughtered by others." "They, too, rely on keen eyesight to find their meals." "Their eyes are so acute they can keep watch over the plains from more than 1,000 feet up." "The warm columns of air rising from the baking ground and captured by their broad wings carries them up with very little expenditure of energy on their part and supports them there." "They scan the ground beneath them, but they also keep a sharp eye on one another." "A lappet-faced vulture is on the ground beside a carcass." "Griffon vultures have noticed it and have started to wheel downwards." "Others have already joined the lappet-faced around the kill." "As more birds glide down, their descent is noticed from miles away in all directions." "And as each bird reacts, the news that a kill has been discovered spreads across the network of watchers in the sky." "More and more start circling downwards towards the banquet." "Within a few minutes, the carcass is submerged beneath a dense scrum of struggling birds." "Lacking feathers on their heads and necks, they do not unduly soilthemselves as they plunge their heads deep into the carcass." "And still more come." "The big cats may make most of the kills on the Serengeti, but most of the meat produced on the plains is consumed, not by lions and leopards, but by vultures." "To human nostrils, the stench of corruption here is overwhelming." "But these vultures are impervious to it." "They can't sense it." "It was the sharpness of their vision that brought them here." "But there's one bird that, exceptionally, has en extremely acute sense of smell." "Here in the rainforest of Trinidad there's an almost unbroken ceiling of leaves above me." "No bird flying in the sky above could see a piece of meat like this lying on the forest floor." "But this is an extremely smelly piece of meat." "Let me hide it." "I can keep watch from a hill that rises above the canopy." "Not a bird in sight." "But there's one, a turkey vulture...and another." "You can tell it's a turkey vulture, because its naked head is not black but red." "And it's always the turkey vultures that are on the scene first." "The meat I put down is directly under there." "And already, it's less than three-quarters of an hour ago, they're beginning to assemble." "It seems almost unbelievable that the smellfrom that small piece of meat could have drifted up through the forest canopy and so permeate the air that it can be detected half a mile away." "It's equally astonishing that the birds are able to measure its relative strength with such accuracy that they can trace it back to its source simply by sensing in which direction it becomes marginally stronger." "But a turkey vulture is exceptionally well-equipped among birds;" "with wide-open nostrils and extremely well-developed sense organs within them." "It's getting close." "There's something in there somewhere." "Got it!" "Their beaks are quite adequate for tearing off strips of flesh, and vultures, after all, do not kill the animals that they eat." "But those that do have to have much more powerfulweapons." "Few animals can survive the grasp of these massive talons." "They belong to the African crowned eagle." "This bird is huge, over three feet long, and it can kill prey over four times its own weight." "It hunts over the canopy of the East African forest and seeks particularly monkeys." "Vervet monkeys seldom expose themselves by venturing into the very highest branches, so hunting them is not easy." "The eagle has relatively short wings for its great size, which helps if it has to plunge through the canopy." "The vervets have a special callthat warns the whole troop that danger threatens from above." "It's caught a monkey." "Its mate joins it, and together they return to their nest." "The chick is only a few days old, too young to tear apart the prey for itself." "It has a lot of growing to do and a huge appetite." "The adults will have to feed it for four months before it is ready to fly from the nest, and nine months after that before it is strong enough to hunt for itself." "To keep themselves and their young properly fed, a pair of crowned eagles need a large hunting ground alito themselves." "So all eagles defend their territories with great vigour." "This one, a sea eagle, is patrolling a forest-covered coast in Malaysia along which it fishes every day." "Those that live in the air have to fight in the air." "And eagles do so with their primary weapons:" "their talons." "Lake Bogoria in the African rift valley, a soda lake fed by hot volcanic springs." "At first sight, a ferociously inhospitable place, and indeed it is, for most creatures." "But although no fish can live in its tepid soda-laden waters, it's nonetheless packed with food for fish eagles." "A million flamingos." "The food chain that sustains a meat-eater could scarcely be shorter than it is here." "Microscopic plants, algae, that can uniquely tolerate these salty waters proliferate in the sunshine by the ton." "Flamingos filter the algae from the water with their beaks, and vegetable is turned into flesh." "And that flesh is food for eagles." "The flamingos have to go into the shallows to drink from the spring that provides the only fresh water in the lake." "But here they are very vulnerable." "As the eagle approaches, the flamingos stampede into deeper water." "The eagle won't tackle them there because it has difficulty in lifting anything much bigger than a fish and carrying it away." "So it can only eat a flamingo in the shallows or on the shore." "This concentration of prey is so dense that pairs of fish eagles have been able to establish themselves every mile or so around the margins of the lake." "But even this number of hunters has little effect on the size of the flamingo population." "Fish eagles normally snatch fish from the surface of the water, they don't usually tackle a bird on the wing, but there is no need to do so here." "Now it has to drag its victim to the shore." "Few hunters can have a greater concentration of prey continuously at their disposal." "The flamingos are back in the shallows." "It would be difficult to imagine a more barren hunting territory than this lava field in the volcanic islands of the Galapagos." "But there's a bird that finds its prey even here." "Although there is little vegetation on land, there is quite a lot in the waters around the coast." "And these bizarre lizards, marine iguanas, graze on it." "They can even swim to the sea-floor to do so." "There they are unreachable by hunting birds." "But they come out of the sea on to the rocks to rest and to warm up." "The big ones are too big and strong for a hawk." "The small ones can scuttle away and get safety in one of the cracks." "But the females, particularly at one time of the year, are vulnerable." "The Galapagos hawks know exactly when that is." "It's the breeding season, when the female iguanas must venture out on to the few sandy beaches to lay their eggs." "Here they can dig the holes they need." "Hawks all over the island keep watch beside the few beaches." "By the time the iguana has finished digging and laying, she must be tired, so the hawk then has its best chance." "But even so, iguanas can run very fast indeed." "If the iguana can reach the rocks, she'll be safe." "This one retreats into the burrow she's only just dug." "She'll have to try and make her escape later." "The outcome is by no means certain." "The iguana is still extremely strong." "But not strong enough." "A number of hawks take advantage of this bounty." "Wounded though it is, this one can still run." "The hawk has lost this encounter." "It can't catch an iguana once it has reached its burrow, even though it might still be able to see it." "But some hawks are especially equipped for snatching their prey from deep within holes." "This is the African harrier hawk." "Its legs are particularly long." "Even more crucially, they are double-jointed, so they can bend backwards, invaluable when groping in the depths of a nest hole trying to extract a chick, as this young bird is doing." "No luck." "But the adult, seeking lizards in the rocks, is more persistent." "It swallows its lizard whole." "This lizard, however, has been caught by a shrike, a much smaller bird and too small to swallow such prey, but neither its beak nor its claws are powerful enough to tear its victim's body apart." "The acacias of Africa provide allthe hooks and spikes that such a bird could need for butchery." "Prey as small as beetles and as big as stoats are treated this way." "Some of the larger animals are left on their skewers, like hung game, so that decay loosens their flesh." "Stocks are sometimes built up in these larders to last a shrike through hard times." "But often the temptation of fresh meat is irresistible." "The lammergeier actually eats bones, but breaking up a large skeleton is an even bigger problem." "A lammergeier, hefty though it is, has not got the beak or claws to do that job." "But like a shrike, it knows a trick or two." "It doesn't just drop a bone anywhere." "It has its favourite patches of bare rock, though sometimes its aim is not as good as it might be." "It's getting a few splinters off this bone." "It can swallow even the sharpest fragment, for its digestive juices are so powerfully acid that bone dissolves very rapidly." "The greatest prize is the marrow and to get that, the big bones have to be well and truly split and that takes perseverance." "A lammergeier may have to drop a bone up to 50 times before it hits rock at just the right angle to split it." "The bodies of other animals provide such rich food that a bird doesn't need to eat a lot of it." "But getting it nonetheless demands not only skill but often a great deal of effort." "An English wood is full of such food, but the dense cover makes things difficult." "But there is one bird that specialises in hunting here." "It flies very fast, very low and takes its victims by surprise." "This is one of its favourite hunting places;" "an old overgrown orchard where lots of woodland birds come to feed on rotting apples and the grubs they attract." "A sparrowhawk visits the wood every day, and waits forjust the right moment." "It knows every twist and turn in its approach flight." "It has flown it often enough before, sometimes two or three times a day." "Its short rounded wings and long tail enable it to fly at speed through really narrow gaps." "Warning calls alert the whole woodland." "This time it wasn't quick enough to catch the bird community by surprise." "This hunter is six times heavier than a sparrowhawk." "It's a goshawk and it hunts not only birds but mammals." "A brown rat." "The goshawk too can manoeuvre through the narrow gaps, but it also has another way of hunting in the woodlands." "It will pursue the rat on foot." "Even though hunters have a formidable armoury and great skill, most of their hunting trips, like this one, end in failure." "The coast of Cornwall, the territory of one of the most highly specialised of all hunting birds." "These are one of its favourite prey, pigeons." "High in the sky, so high it's almost invisible, a peregrine is watching." "Pigeons fly fast." "The peregrine starts its attack." "Wings drawn back, it's travelling at 200 miles an hour." "Striking its victim with its talons at this speed brings instant death." "The peregrine returns to its nest." "It has two eager customers for the meat." "An adult peregrine must kill severaltimes a day if its chicks are to be kept adequately fed." "Five weeks must pass before the chicks are fully fledged and ready for their first flight." "They start with somewhat experimental outings, getting used to the feel of the air in their wings." "Another youngster watches." "Ten days later the young birds are confident enough to tease a passing seagull." "The high-speed aerial pounce, the peregrine's speciality, takes a lot of learning." "You have to be able, in mid-air, to throw your legs forwards with talons outstretched." "Your sibling's tail makes a good practice target." "Now three youngsters join together in the game." "They perfect the manoeuvre that launches the dive, the roll and the pumping of the wings with which the peregrine generates its unique speed." "Tumbling and rolling, diving and striking." "It may seem like innocent play, but like so much play, it's practice for the serious business of adult life." "And now a lesson for advanced students only." "An adult joining the youngsters carrying in its talons a pigeon, wounded but still alive." "And the youngster takes it to make its very first kill." "In a month it will become the swiftest of allthe world's hunters." "But only about a third of the earth is covered by land." "The rest is covered by water, of one kind or another." "There's plenty of food there, too, but you have to learn very different techniques if you're going to go fishing, as we will see in the next programme in The Life Of Birds." "For this brown pelican, the problems of bringing new life into the world have started even before the eggs have hatched." "They've had to be kept cool or warm, according to the time of day, and they've had to be defended." "But that is only the beginning of things." "Once their chicks have disentangled themselves from their shells, the first job of these brown pelicans here in Florida, as it is with all bird parents, is to find food urgently." "Few are in a greater hurry than the Lapland bunting, for summer in the Arctic is desperately short." "Food is rushed in." "Droppings are ferried out." "Both parents labour tirelessly, and since it is light 24 hours a day at this time of the year, they do so non-stop." "As a consequence, the chicks grow at extraordinary speed, and only 12 days after hatching they willfledge." "Dippers are also dedicated and industrious parents." "A nest behind a waterfall is excellently concealed but tricky to visit." "Nonetheless, these dippers, between them, bring a batch of food to their young every ten minutes." "Gouldian finches in Australia make their nests in holes in trees." "The disadvantage of doing that is that it may be so gloomy within that it's difficult to see where the chicks are." "The solution?" "Vividly-coloured spots on the side of the mouth." "And when vibrations made by a parent as it enters tellthese still-blind chicks that food is on the way, they quickly provide extra guidance." "With gapes patterned as vividly as this, the parents have no doubt about where to post their food parcels." "These are zebra finches." "And these extraordinary objects are young firetailfinches." "What look like goggles are actually markers to indicate the corners of the mouth." "These are the chicks of Australian rosella parrots." "Their parents started incubating as soon as their first egg was laid." "That, therefore, was the first to hatch and its chick the first to be fed." "So to begin with, there is a difference in size between the chicks." "But rosella parents are scrupulously fair, and they make quite sure that even the youngest gets its proper share of food." "Even so, after ten days, the eldest is stillthe biggest." "But remarkably, it sometimes shares its food with the youngest and the smallest." "They are beginning to lose their down and proper feathers start showing through." "An itchy business apparently." "Three weeks later, in spite of five days' difference in age between the oldest and the youngest, they are allthe same size." "Rosellas feed their chicks with a regurgitated porridge of chewed-up seeds." "Great-crested grebes, on the other hand, offer their newly-hatched young much stranger meals." "Feathers." "This is not a mistake or an occasional quirk." "Swallowing feathers is essential for the health of grebes." "They form a lining in the stomach which protects it from the sharp bones of the fish, which is the main part of a grebe's diet." "When the chicks grow up, they will swallow their own feathers, but now their parents obligingly provide them." "And that's just as well considering the size of the fish that the youngsters are prepared to tackle early on in their young lives." "These open-billed storks, nesting in the sweltering heat of Thailand, have also got young chicks." "One of their problems is keeping cool, and one of the ways of solving it, of course, is to take a nice cool shower." "But some showers are nicer than others." "The adults bring water back to the nest in their crops, and empty it over the featherless chicks." "But showers are not the only things that the chicks need." "Sitting virtually naked in the baking sun could be lethal." "During the hottest part of the day they are in desperate need of shade... and the parents provide it." "The storks, like many birds, are exemplary parents, tending to the appetite and the comfort of their offspring with care and devotion." "But not all birds behave in such a way." "It's an idyllic scene - a pair of birds devotedly caring for their chicks in the springtime." "But for the adult birds, this is a very testing time, particularly if, like these coots, you may have as many as nine chicks and the food supply is far from certain." "Things start well enough." "One of the adults uses particles of food to tempt a newly-hatched chick down from the nest and on to the water." "The little flotilla sets off under the care of both parents." "But the food they prefer comes in very small instalments - tiny shrimps and water insects." "It takes a lot of collecting." "And there are other troubles and stresses." "Trespassers can't be allowed on to the coots' feeding grounds." "They have to be seen off, no matter how big they are." "Then, nearly always on the third day, the parents begin to lose patience." "A chick begs for food yet again... ..and is punished." "Each chick in turn gets this harsh treatment." "Maybe the adults are testing them to see which are the strongest." "After a time, they concentrate their punishment on one, and to such a degree that it stops begging and so starves to death." "But unless there is a superabundance of food, the persecution goes on." "In the end, the coots will only raise two or three out of their brood of nine." "Life for young pelicans can be equally brutal." "As they grow, so do their appetites." "No matter how hard the parents work, they cannot bring enough food for allthree." "The last to hatch was always smaller than the other two." "It was always the last to be fed, and now the two older ones turn on it." "Now it will not survive." "Its parents will not bring any food to it on the ground." "And that's not the end of it." "No sooner has one been pushed out of the nest than a second willfollow, untilthere is only one left." "And that's what happens nearly always in a pelican's nest." "That being the case, it seems rather inefficient, not to say heartless, that the pelican should always lay three eggs." "But the reason is that it's partly an insurance policy." "In case something terrible happens to one or two of the chicks, there's always a third left to carry on;" "and partly because, very rarely, when the fishing is very good, it is possible to raise more than one chick." "So bringing up the young is a very demanding business indeed." "And in most birds it requires the full-time labour of both male and female." "But one or two birds manage to avoid it altogether." "And one of them is a regular visitor to this reed bed in England." "A cuckoo, and she is raiding a reed warbler's nest." "That's one of the reed warbler's eggs gone." "And while she holds a second in her beak, shuddering with the effort, she lays one of her own." "The match is near perfect." "The cukoo's is the one at the front." "The reed warblers don't notice the difference and continue incubation." "The cukoo has timed her action with care." "She laid her egg immediately after the female reed warbler laid the last of hers, but it develops much faster and will hatch three or four days before the legitimate eggs do." "The young cuckoo, blind and naked, now deals with the remaining warbler eggs." "Two weeks later, the monstrous young cuckoo is so big that it can no longer fit inside the tiny nest." "Its brilliantly-coloured gape, together with its call, that mimics the sound of a brood of warbler chicks, constitute a demand for food that the warblers find irresistible." "The European cuckoo's habit is so famous that we tend to think it is the only bird to behave in this way." "But there are birds in half a dozen other families that do so as well." "Here in Argentina, brown-hooded gulls are nesting." "Gulls are so vigorous and enterprising that they might seem the last birds likely to be tricked, but on occasion they are." "A duckling." "Its true parents, cuckoo ducks, are far away from the nest where they dumped their egg." "Their offspring will never see them, just as they never saw their parents." "The duckling cannot know that it is quite different from the baby gull which has now hatched out alongside it." "Nonetheless, something tells it that it must not stay with this other nestling." "On its very first evening, it leaves." "Unlike the cuckoo, it makes no further demands on the bird that incubated it." "Even though it is only a few hours old, it is perfectly capable of fending for itself." "Young goldeneyes also have a somewhat precipitate start to life." "The female goldeneye regularly lays in a woodpecker's hole." "But when her young have got over that handicap, she solicitously leads them down to water, for that's the only place where they, like most ducklings, can gather food for themselves." "Here in British Columbia, there is no shortage of lakes, and their mother goes ahead and calls to them to join her." "This lake, however, has already been claimed - by another female goldeneye with her brood." "And she is very possessive." "There's going to be trouble." "The newcomer has to leave." "But her ducklings can't fly away with her." "So they join the resident family." "That's no problem for mother." "They can fend for themselves." "And having an enlarged family reduces the chances of her own ducklings being taken by a hungry fish or a hawk." "In the end, she may accumulate a flock of twenty or more." "A river in the high Andes." "Unlikely though it may seem, some ducks manage to live on these racing waters as well - torrent ducks." "These have made their nest in the rocks thirty feet above the water, high enough to be safe if the river were suddenly to rise." "But that means that these ducklings also have a very hazardous journey to make." "Even mother has a little trouble." "The racing water might seem to pose even greater problems than the slippery rocks." "But the ducklings are so buoyant that they float on the surface, and are in no danger of drowning." "Nor are they swept away, for, miraculously, they know instinctively how to shelter in the eddies in the lee of a boulder." "And once launched, they, too, can feed for themselves." "Summer on the Arctic tundra." "Brent geese came up here a few weeks ago, to feed on the newly-sprouting vegetation and to nest." "Now their offspring have hatched." "They too will have to face a dangerous journey before they can feed." "This pair built their nest within a few yards of a snowy owl's nest." "That was good sense, for ground-nesting birds here are likely to be attacked by foxes." "Owls are quite prepared to tackle foxes." "And so they seldom venture near." "While they were incubating, the geese benefited greatly by nesting beside such a powerful neighbours, but now their eggs are hatching and that will change things." "Owls feed on lemmings." "And lemmings are about the same size as goslings." "Somehow, these little creatures will have to avoid becoming one more meal for a hungry owl." "But they must leave their nest if they are not to starve." "Their parents are well aware of the danger." "Equally, the male owl can see that there is a mealto be had." "Parental bravery wins the day." "Two birds to guard the young are good." "Three are even better." "Magpie geese live in northern Australia, and the journey their goslings have to make in order to feed is also dangerous." "Magpie males are very unusual in that normally they will mate with two females, who will both lay in the same nest." "So it is usually three adults, and only occasionally two, that escort their young." "In the skies above, a sea eagle." "It spots a trio with chicks..." "..and they manage to see it off." "A pair are an easier target." "Angry and brave the two adults may be, but it's too late." "Attacks can come not only from the sky, but, more unexpectedly, from below." "Crocodiles." "Even the adults themselves are now in real danger." "And the goslings are very vulnerable indeed." "The pair have made it, but only two of their five young have survived." "The trio has succeded in bringing down four or five chicks." "Here in the feeding swamps, there is comparative safety." "All can join in keeping eagles away, and the water is too shallow for crocodiles." "Nonetheless, overall, the journey cost many young lives." "But the families that lost least were the trios." "So there really is safety in numbers." "And here in the Seychelles, numbers are astronomical - a million sooty terns." "Here, surely, there must be safety from predators." "But egrets stand around the fringes of the colony, and they will swiftly seize a chick if it's left unguarded." "A chick is such a good meal that the egrets will even risk stabs from the beak of a parent to get one." "Further into the colony, the chicks are surrounded by a great crowd of adults, and are very much safer." "Even a few yards from the edge, the egrets face such determined and effective opposition from all directions that they stand little chance of success." "Chicks that have the luck to hatch in the very centre are five times more likely to survive than those on the edge." "And there's another way for a bird to protect its chicks." "Rear them in a place so remote that few other creatures can get there to threaten them - a place like the Australian desert." "Here banded stilts nested beside a temporary lake." "Soon after their eggs hatched, the females left and started nesting again elsewhere." "Now the youngsters have gathered in groups several hundred strong, with only just a few males left behind to keep an eye on them." "The job is not too difficult, for the salty waters are full of tiny shrimps that the young stilts can collect for themselves." "For other birds, however, finding food is so difficult that even two parents can't feed their chicks unaided." "Farther south in Australia, in the eucalyptus woodland, white-winged choughs have that problem." "Their young feed on beetle grubs, and those are so difficult to excavate that a pair will need at least two adult helpers to keep one chick fully fed." "And the more helpers they have, the more chicks they can raise." "This chick is almost fully grown and so has a very big appetite." "Allfour birds labour away to keep it supplied." "Eventually, however, it will change from being a liability into an asset, a young bird that can help in rearing a chick next year." "Another group of choughs appears in the trees." "It has many more members." "The residents are worried, and show their agitation by goggling their eyes." "This is a press gang." "They are kidnappers." "And this is what they are after." "One of the raiders starts to display to the chick, trying to entice it away from its parental group." "And it follows." "A kidnapping has been achieved." "The raiders feed their new recruit, and it joins the group's own youngster." "Now they have two juveniles." "Next year, the support team will be so big that they may be able to raise three or even four chicks." "So having difficulties in raising baby can lead to sociability among adults." "But perhaps the most sociable of all birds, birds that behave almost like a troop of little monkeys, live here in the deserts of the Middle East." "An Arabian babbler." "But you hardly ever see just one." "Arabian babblers do everything together if they possibly can, and that certainly includes taking a bath." "After a bath, the whole group sunbathe together." "Once dry, they preen each other." "In fact, Arabian babblers do most things as a group." "They all share the labour of collecting food for the group's chicks." "They also share the responsibilities for defence, taking it in turn to act as sentry." "When another sentry comes on duty, it brings a morsel of food as part of the hand-over ritual." "A viper!" "The sentry sounds the alarm." "The whole group assembles." "By creating a commotion, they ensure that everyone is aware of the danger." "They also discomfort the snake and perhaps distract it from hunting." "It may also be that some of them, by deliberately taunting the snake at close quarters, are demonstrating their strength and fitness in a way that will give them respect and seniority within the group." "Once the danger is past, life returns to normal." "The sentry goes back to guard duties, and the youngsters start to play among themselves." "Many young birds are abandoned by their parents almost as soon as they are capable of flight, so they have little chance to play and gain the skills they will need as adults." "But the babblers form such a coherent group that the juveniles can spend time doing just that." "For the young anhingha in Florida, learning through play is essential." "If it doesn't become a skilled juggler quickly, it will starve." "It must learn to do this." "Of course, it is important when playing with a stick not to take the game too far." "Gannets also fish by diving, and that is a skillthat can't be practiced by the young untilthey can fly." "The parents dealwith this problem by feeding their young so generously that, by the time they've fledged into their dark immature plumage, they've accumulated reserves of fat that will sustain them while they are learning to catch fish for themselves." "So now they are heavier than their parents." "But that extra weight is a liability." "It makes it more difficult for the young to fly." "The seas beside this South African colony are dangerous, and not only because of the pounding surf." "Had there been cliffs from which to launch themselves into the air, as there are around many gannet colonies, their first flight would be easier." "But there aren't." "No wonder they appear nervous about taking off." "Fur seals are waiting." "But in spite of the seals, many young gannets do manage to get into the air." "Flight for young birds is the essential skill, and the penalties of failure can be fatal, so birds do allthey can to prepare for it." "The young open-bill storks, now fully grown, are strengthening their flight muscles with regular exercises." "A young hummingbird cautiously practices hovering while still in the nest, even though that makes life somewhat difficult for its sibling." "On the tundra, the snowy owl chick, still semi-clothed in down, has got plenty of room for practice." "And the surviving brown pelican at last leaves its platform nest." "It joins other youngsters sitting at the edge of the sea." "Each has already survived many perils in its young life." "As a chick, it fought battles with its brothers and sisters and won." "For nine or ten weeks, it was devotedly fed and protected by its parents, but now it's on its own." "If it in its turn is to raise young, it has many more battles ahead of it out there on the sea and in the air." "Life for all birds everywhere can be hard, but some species have become specially adapted to the harshest environments on Earth." "How they do so you can see in the next programme, the last in this series about The Life of Birds." "Birds are masters of the air and can gather food from anywhere on the land." "But most of the earth is covered with water and so some birds, early in their history, became extremely competent there too, both in it and on it." "These shallow gravelly streams here, in the New Zealand Alps seem desolate places devoid of any food." "But look at the underside of this pebble I've just picked up;" "Several succulent insect larvae." "And in fact, these streams, like waters fresh or salt all over the world, are full of food." "When you consider that two thirds of the world is covered with water, that's a huge resource." "No group of animals living out of water have developed a wider range of techniques, and indeed tools for, collecting that food than the birds." "This one is unique." "The only beak in the entire bird world that is bent to one side." "This is the wrybill, which only lives here in New Zealand." "Its extraordinary beak enables it to probe beneath large heavy boulders that it couldn't possibly turn over or even shift." "And just in case you're wondering, the bend is always to the right." "Dippers plunge right into the streams." "This one is in Yellowstone, in the American West, where hot volcanic springs keep the streams clear of ice in winter, so that the dippers can walk underwater throughout the year." "Their dense, oily plumage retains air to such a degree that it forms a silvery cloak around their body and so keeps the birds warm." "The disadvantage of that coat of air is that it makes its wearer very buoyant, and the dipper has to struggle hard to remain below the surface." "They seldom manage to stay underwater for much more than a quarter of a minute at a time." "Kingfishers are only underwater for a second or so." "They are living harpoons." "This is one of the bigger members of the family, the belted kingfisher." "It's the size of a small crow, and lives beside rivers and lakes all over North America." "Understandably, it prefers places where the water is clear so it can get a good view of its targets." "Having caught the fish, it must now stun it, and to do that the fish has to be head outwards." "But if the kingfisher is to swallow it without the spiny fins sticking in its throat, it has to turn the fish around again." "Most kingfishers dive from perches." "That means that they are more or less tied to the shore." "Only one of them is able to break that link." "This is the African pied kingfisher, and it can launch its dive from high in the sky because, even in completely still air, it can hover." "It's the biggest bird in the world to be able to do this." "It's not only a diver, sometimes it's a juggler." "The darter does its harpooning underwater." "It's so at home there, that it can actually creep up on its prey." "Missed." "It always has to juggle to get its catch off its harpoon." "The darter doesn't have the dipper's problem with buoyancy because its feathers actually absorb water." "But that means that it gets soaked to the skin, and after a swim, like anyone in a wet bathing costume, it has to dry itself quickly and thoroughly if it's not to get a chill." "Some fish are incurably inquisitive." "The little egret can attract them by doing no more than waggle its yellow feet." "It seems a simple enough trick, but it works nonetheless." "Birds all over the world have devised all kinds of bizarre solutions to the problem of extracting little fish from shallow pools." "In the swamps of Florida, the reddish egret performs an improbable kind of dance." "The idea seems to be to frighten the little fish out of their hiding places." "Shading your eyes can help you see what's down there, beneath the reflections." "And there was something." "In Africa, the black heron takes the business of shading its eyes very seriously indeed." "Maybe cutting out reflections is not the only reason for doing this." "Many fish prefer to swim beneath an overhanging bank or a tree, so they can't be easily seen from above." "So perhaps they deliberately take shelter under the heron's wings, which, of course, could be a mistake." "The spoonbill isn't really after fish." "This scything action of its beak enables it to gather tadpoles, beetles and insect larvae, but it must also scare little fish, which then dash off to seek safety." "So it's worthwhile for the black heron to follow the spoonbill around, just in case." "The pygmy cormorant certainly is after fish, and therefore thinks it's a good idea to follow the heron." "Maybe the heron is having better luck." "All in all, a little fish doesn't stand much of a chance in a shallow pool like this." "These too are fishermen, but they don't wade, they skim." "And to do that they need not long legs, but a long beak." "Or to be more accurate, a long, lower mandible." "The upper one is more or less normal in size." "This is the skimmer, a highly specialised relation of the gulls." "Their chicks, in fact, look very like gull chicks." "They don't develop that extraordinary beak untilthey are some three months old." "Skimming, although it demands flying of the greatest precision, is straightforward enough in principle." "As soon as the lower mandible, ploughing through the surface of the water, touches anything solid, a reflex action will make it snap shut." "That sounds fine, but supposing the beak hits something really big, like a floating twig or, worse, a submerged rock, what then?" "Well, the fact is, that quite a lot of skimmers have broken mandibles." "Whatever the hazards, overall, the technique is a very succesful one." "The chicks have to be fed for six weeks and skimmers are faithful, hardworking parents, bringing food every ten minutes or so, for hours on end when the fishing is good." "But while they are certainly devoted to their young, they are sometimes just a little optimistic." "Oh well, if baby doesn't want it..." "Skimmers and egrets and kingfishers live beside the water." "Some birds live actually on it." "Mallards must be one of the most familiar birds in the world." "Because of that, perhaps we tend to take ducks for granted." "But in fact, they are a very varied family." "Different species are adapted to different ways of life on water." "Mallards, for example, are specialist dabblers." "They find allthe food they need by doing no more than dipping their heads beneath the surface." "And there's lots of food to be found that way;" "duckweed, tadpoles, weeds and seeds, and bits of bread thrown in by friendly humans." "If the food they have spotted is really deep down, they will up-end totally." "If that doesn't get it, it's beyond their reach and that's that." "Ducks keep their plumage water-resistant by anointing it with oilfrom a gland on their rump." "They also keep their feathers clean, soft and pliant by frequent and enthusiastic bathing." "Ducks don't alljust dabble." "Some dive deeper." "The merganser has webbed feet, like the mallard and all other ducks, but they are placed very far back on the body." "That's the best place to have a propeller from a mechanical point of view, and as a result they can swim quite fast enough to catch smallfish." "Their bills are notched like a fine saw, which helps when you have to grapple with a slippery fish." "The young start diving almost as soon as they've hatched." "But they're still covered in down, and that makes swimming underwater very difficult indeed." "They use up far more energy than their streamlined parents do." "The most skilful underwater swimmer of allfreshwater birds, however, is the diver." "This is an immature one, that has not yet got its spectacular black and white plumage." "Its feet are placed so far back on its body, that out of water it can hardly walk, but underwater it's superbly manoeuvrable." "Smallfish have little chance." "That's very usefulfor keeping warm, it can be very windy out there on the lake." "But as the mergansers demonstrated, it causes problems when diving." "And young divers don't even try." "Diver chicks, it has to be said, are rather pampered." "They're regularly given lifts." "And while one of their parents ferries them around, the other finds food for them." "The male finds a fish, but decides to eat that himself." "He's been away a long time and the family is getting hungry." "But now he's found a crayfish." "That will do for them." "The crayfish is carefully broken up, and passed over to the chicks a little piece at a time, with great delicacy, and quite a lot of patience." "They get shallower as rivers dump sediment in them, and in the tropics, they may even dry up every year." "As a result, all sorts of delicious things come within reach, as they have in this African pool." "The openbill stork has a special liking for mussels, and a specialway of opening them." "First, a sharp squeeze to make the shell open slightly." "Then the lower mandible is slipped in, to cut the body away from the shell." "After that, it's easy." "Snails require a slightly different treatment." "To start with, they have to be taken on to solid ground." "Now the little disc, with which the snail can seal its shell, has to be removed." "That's done by delicately squeezing it in just the right place." "There!" "Then, once again, the muscle that attaches the snailto its shell has got to be severed." "And out it comes." "As the dry season progresses, yellow-billed storks travel in flocks, from one drying river bed to another." "When the water started to shallow, many of the fish retreated to the main river." "Those that didn't are now trapped and doomed." "The yellow-bills have a labour-saving technique for fishing in these overcrowded pools." "They just hold their beaks open and wait for a fish to blunder into them." "Only one kind of fish is likely to survive the coming drought." "The lungfish will soon cocoon itself in the mud at the bottom, and remain there, dormant but still alive, even when the river bed is bone dry, because it can breathe air." "But before it cocoons, it has to survive another peril." "The shoebill stork has a massive and murderous beak." "It also has keen eyes." "And infinite patience." "One bite crushes the lungfish's skull." "But it stillwriggles and takes quite a bit of swallowing." "On the margins of the land, the water retreats not just once a year, but twice every day." "That exposes a completely different menu, and birds compete in order to be the first to collect it." "Here in California, there are some that take almost suicidal risks in order to do so." "The surf bird is the clear winner." "No bird gets to an edible morsel cast up by the waves quicker than it does." "It has split-second judgement." "It may also be that it gets so close to the waves because that gives it the chance of catching a barnacle or a mussel, before it has fully reacted to its exposure to the air, and closed its shell." "Where the coast is less rocky and the beaches are sandier, the waves are less violent." "Here birds of several different kinds will assemble, but they are not always in competition." "Each collects from a particular place with a particular kind of implement." "The godwits have long beaks with which to probe deeply into the sand for worms, crustaceans and little molluscs." "Dowitchers, with shorter beaks, collect the same sort of thing but from nearer the surface." "Sanderlings pick up bits and pieces that have just been washed ashore." "Out in the shallow water, avocets are after shrimps, and other swimming creatures that don't allow themselves to get stranded on the beach." "The avocet holds its bill with the curved section just slightly parted, and as it sweeps it through the water and the mud, small invertebrates are carried into it." "The bill is so sensitive that the avocet feels when something good has arrived, and swallows it." "Fish also come into the coastal shallows, seeking the same sort of thing." "And when they do, they become the target of pelicans." "With a billthe size of a pelican's, you don't have to have pin-point accuracy." "It does help, however, for pelicans to feed in groups, for then fish fleeing from one lunging bill may blunder into another." "The brown pelican also dives." "But rather clumsily." "It's so big and buoyant, that it only goes a few feet down." "It's very often accompanied by noddy terns." "They know that the pelican has to open its bill and get rid of allthat water before it can swallow any fish it might have caught." "And when it does, they might get a chance to steal part of its catch." "So now it's a question of who loses patience first." "The pelican cautiously opens its billjust slightly, and the water begins to seep from its pouch." "Done it, this time." "Boobies live on the coast, but their fishing grounds are way out in the open ocean." "Every morning they leave their roosts and set off in small parties to scour the surface of the sea." "They are searching for a pale greenish patch in the blue of the ocean that betrays the presence of a dense shoal of fish." "The fish have been driven to the surface by a shark that is still lunging into the shoal." "And now they are subject to an aerial bombardment." "As the boobies dive, they draw their wings half back so that they can still aim, and only fully retract them just before they hit the water." "The bombardment will continue until either the shoal manages to escape downwards, or the fading light of the evening forces the boobies to return to their roost on the coast." "Boobies don't actively swim underwater, but members of the auk family, such as these guillemots and puffins, do." "They propelthemselves, not with their feet, like ducks, but with their wings, and they have paid a considerable price to be able to do so." "The wings of a booby or a gull are far too long and insufficiently robust to be beaten underwater." "So auks have had to evolve shorter, stubbier wings." "That gives them a rather clumsy, whirring flight in the air but it does enable them to fly underwater so well that they can outpace smallfish." "One family of birds has taken this development even farther, and one of them lives here...in the Galapagos." "We tend to think of penguins as sitting around on ice floes in the freezing waters of the Antarctic, so maybe these little penguins sitting right on the equator seem odd to us." "But in fact, these little ones are probably much more like the original ancestral penguin than their giant Antarctic cousins." "Because those first ancestral penguins certainly flew, as well as dived, as guillemots do today." "And if you were much bigger than this and had a wing shaped like a flipper, which is what all penguins need to swim, you would never get into the air." "So maybe these little ones are more like the first of the penguins." "Penguins underwater look somewhat like dolphins and indeed the two families have similar evolutionary histories." "Dolphins are descended from air-breathing land animals, just as penguins are descended from air-breathing flying animals." "Both subsequently took to swimming for their food." "They became beautifully adapted and streamlined." "And now, both are superlative swimmers and highly accomplished fishermen." "Some members of the penguin family can dive for 5-6 minutes without taking breath and descend to depths of a thousand feet in search of food." "Indeed, the only thing that limits penguins as swimmers, is their need to breathe air." "There is, however, one link that stillties them, and indeed all birds, to the land." "They all have to return there in order to lay their eggs." "For sea birds, the ideal place to do that is a remote island which has very few, or preferably no land-living predators." "(IMITATES BIRD CALLS)" "Nobody knows why it happens, but when you make strange noises here, sea birds fallfrom the sky." "I'm on Lord Howe Island, a tiny speck of land 300 miles off the east coast of Australia." "Human beings only got here little over 200 years ago, and it seems that the birds that nest here are still quite curious to see what's going on." "And these birds which are coming to these calls are Providence petrels." "Skilled in the air they may be, but they are certainly clumsy and ungainly on land." "When they do come down, they squabble and wrestle furiously with one another." "Perhaps they're arguing about who shall have which patch for a nest hole." "But they are still extraordinarily friendly towards human beings." "And, amazingly and very touchingly, it will stay here on my hand in a very trusting way and it gives me a chance to look at the structure at the base of its beak." "It has a tube-nose, and that structure, which it shares with a number of other ocean-going birds, is absolutely crucialto their survival out on the open ocean." "And that is where he is going to go right now." "That tube channels air to a sense organ at the base of the beak which can detect very faint odours." "That's a rare ability among birds, and it enables the tube-noses to find floating food from great distances away." "I'm at sea, 20 miles out from the east coast of Australia, and in this bucket I've got a particularly attractive liquid." "It's, eh, fish oil, it's very nutritious." "Being oil, it'llfloat on the surface of the sea, and above all, it smells very powerfully." "And at the moment there's not a bird in sight." "But watch what happens when I put it overboard." "The first to arrive are sooty shearwaters and Cape petrels, closely related to those Providence petrels on Lord Howe Island." "It's not only the smell of fish oil and offal to which they are sensitive." "It's recently been discovered that when small shrimps and other floating creatures feed on floating plants, algae, those plants release a gas, that in strong concentrations smells a little like rotting seaweed." "The petrels can sense even a faintest whiff of this, and so can find places where they can collect the shrimps." "Now very much bigger ocean-going birds arrive." "These magnificent birds are albatrosses." "They, too, belong to the tube-nose family, but the tube on their beaks is comparatively small." "In fact, they find their food more by sight than by smell." "They have enormous wing spans." "Two of them, the royal albatross and the wandering albatross, have the biggest wing span of any living bird." "And they circle the globe in search of food." "This is a yellow-nosed albatross." "It's not quite as big as a wanderer but it's still a very large bird, with a seven foot wing span." "No birds exploit the ocean winds with greater skill than the albatrosses." "Reading its force with peerless sensitivity, they're able to adjust their immense wings to exploit every tiny updraft deflected from the waves beneath." "So they can glide for long periods without expending any energy at all on flapping." "The wandering albatross rides the violent gales of the southern ocean, and willtravel a thousand miles to bring back a cropful of food for its chick." "The chick takes nearly ten months to grow strong enough for an ocean-going life." "So although the albatross, when young, may roam the oceans for severalyears without touching land, eventually the need to breed brings it down to earth." "One bird has managed to break this long obligation to return repeatedly to land to feed its chick." "It's called the ancient murrelet, and it doesn't feed its chick on land at all." "The only place it nests are on islands around the northern rim of the Pacific, like Canada's Queen Charlotte Islands, where I am now." "And the only time you are likely to see it, is at night." "This is one of their nest holes." "The chicks, when they're only two days old, make one of the most astonishing journeys made by any chicks." "The parents come back from the sea at night and, crouching on the ground, callto their newly hatched young." "In response, the chicks come out of their holes, running." "There are large aggressive mice that will catch them if they get the chance." "Ravens and eagles are also active during these light nights." "The chicks are in real danger." "So they run, and run fast." "Their parents have gone ahead of them, and are now calling from the sea." "By midnight there are young chicks swarming all over the forest floor." "Most of them managed to get to the beach within ten minutes of leaving their holes." "But their parents are not here." "They've gone farther out, just beyond the breakers, and they're still calling." "The chicks don't stop." "They keep pedalling, like little clockwork toys, and the same movements that propelled them across the ground now take them out to sea." "In some miraculous way, each chick recognises the sound of its parents' voice." "United, the little families leave the land and its dangers and sail away into the relative safety of the open ocean." "The chicks are still only a few hours old." "The ancient murrelet must be the most truly oceanic of all birds." "Dawn, and there's not a single one of those little chicks to be seen." "By now they are all at least four miles out to sea, called there by their parents." "Sound, of course, is very important in the life of all birds." "It's the way they communicate." "And what they say, and the various ways in which they say it, is what we'll be looking at in the next programme about The Life Of Birds." "It's spring in Sweden." "Fieldfares are industriously ferrying meals of worms to their ravenous chicks." "They nest in colonies, up to thirty or forty in a group, and that helps a lot with defence, which is important, for there are plenty of raiders around." "That was one." "It's a young raven." "He's after a nestling." "A fieldfare has spotted him and sounds the alarm." "Others take up the call, and the defence force assembles." "The raven now knows that he's been spotted, but he's hungry." "The fieldfares, screaming with anger, converge on their enemy." "And now threat turns into direct action." "They mob him." "Thoroughly intimidated by the commotion, the raven retreats." "But the fighters press home their attack, and the raven is brought down." "And now they bomb him with their droppings." "Soiled feathers soon become waterlogged, and that could be crippling, even fatal." "Thoroughly cowed, the raven retreats." "The colony is saved, thanks to its members' highly effective system of communication, between themselves and with their enemy." "The messages proclaimed by those Scandinavian fieldfares could scarcely be misunderstood, even by us." "The first were calls to arms, the second were battle cries designed to intimidate the enemy." "But alarm calls aren't always so easily recognised by outsiders." "Sometimes it's better to sound the alarm more surreptitiously." "And that is something that birds in an English wood do very well." "(BIRDS CHIRP)" "That sound, for example, is a general alarm call." "It's short, very high-pitched, and that makes it very difficult to locate the bird that makes it." "It's a great tit." "Half hidden among the leaves, he continues sending furtive signals to his family, but allthe birds around get the message." "An enemy would find it very hard to detect where that sound is coming from." "Another warning." "This time it's from a robin." "He's telling his mate to stay still untilthe danger has passed." "And that's the blackbird's version." "The begging cries of nestlings could put them in danger." "A male chaffinch tells them to keep quiet." "And they do as they're told." "This surreptitious call is like an international distress signal understood by everyone." "(BIRDCALL)" "But that's a different kind of message." "That's not one that's sent surreptitiously to others." "It's aimed directly at me." "It's a warning to tell me that I've been spotted." "I'm too near this blackbird's mate who's sitting on her nest." "His calls are almost continuous and much lower pitched, because he wants to be located, so that he can distract me away from her, and even unsettle me." "Sound is not the only way to spread the alarm or intimidate an intruder." "Some birds do the same thing visually." "Most of the time, this sunbittern is well-camouflaged and unobtrusive." "Even less conspicuous than the jacanas and the cayman that also haunt the river's edge here in Venezuela." "The river is continually bringing edible bits and pieces within range, and the sunbittern lives on them." "But he has competitors." "A hawk in the branches above has spotted something." "So has the sunbittern." "But the hawk gets there first..." "..and collects it." "A second hawk arrives." "If the sunbittern is to get anything at all, it will have to frighten the others off." "So it transforms itself." "A ferocious, hissing, two-eyed monster that doesn't exist is saving the day." "The hawk tries again." "But this startling display has convinced the hawks that the bird down there is dangerous, and they give up." "There is, of course, an alternative signal." "Instead of saying "I am here and extremely formidable", you could say "I'm not here at all"." "That, of course, is a straightforward lie, but there's a bird in these Brazilian forests that tells the most convincing of lies." "Finding it is not easy." "Indeed, I'm quite sure I've walked past one many times without knowing it." "But this time, we're lucky." "It's sitting on the tree trunk." "It's a potoo, a kind of nightjar." "It hunts for insects at night, so, like any other nightworker, it needs to rest during the day, and it relies on the visual match between its feathers and the tree trunk to protect it." "The only thing that could give it away are its beak and its eyes." "Now I am getting quite close, so it decides to improve its disguise even further." "And it does that by changing its posture and closing those give-away eyes." "Now it's no more than the stump of a broken branch." "You might think it would be dangerous to shut your eyes just when danger approaches." "But, in fact, although its eyes are shut, it can still see me." "There are two little hitches in its upper eyelid, and its night-vision eyes are so sensitive that it can still see what's going on." "As it watches me going away, it relaxes and returns to its doze." "Most birds, of course, rely on their ability to fly to keep them out of trouble, and so, as you walk through an English wood, they too vanish." "But establish their confidence and they will soon come back." "And then you can see that they use their plumage to send very different messages." "One finch meeting another needs to know whether or not it's the same species." "If it is, it could be a rival, either for a mate or for territory." "If not, it can be largely ignored." "So finches with such similar body shapes wear uniforms that make plain who they are." "And what works for other birds will also work with us, provided we know the code." "Most bird-watchers do." "A grey-blue cap and reddish cheeks identify a chaffinch." "A brown head and grey colour, a hawfinch." "A completely green head, a greenfinch." "A black cap and red cheeks, a bullfinch." "And a red face and forehead, a goldfinch." "So every finch knows whether another is a rival or not, and there are no pointless quarrels." "In the forests of Indonesia, hornbills also use colour codes." "Several species there have predominantly black and white plumage." "This one, however, the pied hornbill, has yellowish areas on its white wing patches." "These are not accidental smudges." "This bird uses make-up." "With its beak, it squeezes a yellow oil from a giant preen gland on its rump." "And it uses that oilto paint on those yellow blotches." "And it's not just on its wings." "It adds yellow patches to its neck as well, though they are more difficult to put on." "Even its huge bill owes its yellow colour to the preen oil." "Different kinds of hornbills paint themselves different colours." "Whether these cosmetics are used just for appearance's sake, or whether they have an additional purpose, we don't know." "But one thing is quite certain - birds take a lot of care over their appearance." "All birds have good eyesight, a necessity if they are to navigate at speed through the air." "In particular, they have excellent colour vision, and that enables some species to have the most gorgeous uniforms." "I can attract some of the most spectacular using this bottle of artificial nectar." "The particular glory of hummingbirds are their bibs and breast-shields." "Their colour is not pigment but an optical effect created by refraction, like the colours on a film of oil on water." "They are particularly attracted by red, which is why I have got red artificialflowers on this bottle." "They can also see in ultraviolet, a colour that lies beyond the range of the human eye." "It's recently been discovered that many of their feathers reflect ultraviolet, so the likelihood is that these brilliant costumes are even more vivid in their eyes than they are in ours." "Many birds that we might think are plain are almost gaudy in ultraviolet light." "If we look closely at starlings, we can se a sheen to their plumage, but that has an ultraviolet component that makes them appear much more vivid to one another." "Blue tits, in our eyes, are one of the more colourful of our garden birds." "But in ultraviolet they are much brighter still." "Their crests are particularly vivid and much brighter in males than females." "So to them, the sexes look very different, whereas to us blue tits all look the same." "We would all, I imagine, think that budgerigars are unusually colourful birds." "But ultraviolet radically changes the character of their costume." "Their feet glow." "And the spots on their cheeks, which are not very prominent to our eyes, positively blaze." "Indeed, a budgerigar's full-dress uniform is dramatic in the extreme." "Uniforms not only indicate an individual's regiment, but his rank within that regiment." "Male sparrows have black bibs, but the size varies." "The more vigorous birds have bigger bibs and therefore higher ranks." "Sparrows forage in flocks, and when there's lots of food in a small area, you might expect lots of quarrels, but there aren't." "This is a private, with no badges." "This one is somewhat senior, a sergeant, perhaps." "A captain." "And the colonel." "There could be disputes not only over food but over amenities like dust baths." "The privates are squabbling among themselves." "But watch what happens when a corporal steps in." "Junior ranks retreat." "Or when a corporal gets too close to a sergeant." "A sergeant, however, will give way to a captain." "And no one should think of parting a colonelfrom his lunch." "A quick flourish of his insignia is quite enough." "Among birds that don't live in flocks there's no need for the ranking system to be so multi-layered." "Moorhens may mingle, but each pair has its own territory." "Their badges are the red beak and head shield and the white patches on either side of the tail." "Rivals assess one another's strength by the size and brilliance of those head shields." "If they feeltheir ranks are equal, then they may not want to contest the position of the boundary, and they display the white tail patches to indicate that the confrontation is being broken off." "But here, the male on the right is standing boldly upright." "He reckons he is the senior, and he wants to enlarge his territory." "The time for sending messages is over." "This quarrel can only be settled by physicalviolence." "Birds can get badly injured in these battles, but they have to be fought if a senior bird is to establish and retain his rank." "Eventually the junior bird surrenders." "A new line has been drawn." "They won't need to fight again as long as it's not over-stepped." "Communication by visual signals, however, has one major limitation." "Except in completely open country, they only work at close range." "In forests, sound signals willtravel much further." "So if a bird, in order to get enough food, needs a very large territory, it is likely to declare its territorial claims with sound." "There are, of course, many different ways of making a noise, and knocking on a resonant tree trunk is one of them." "In this part of the world, in Patagonia on the southernmost tip of South America, two knocks on a tree trunk has a very particular meaning, at least among birds." "If I do it, I might even get an answer." "(WOODPECKER KNOCKS ON TREE)" "(WOODPECKER KNOCKS ON TREE)" "(WOODPECKER KNOCKS ON TREE)" "It's a Magellanic woodpecker, one of the largest of allwoodpeckers, and he thinks he has heard a rival." "He comes in for a closer look." "(WOODPECKERS KNOCKING)" "And here's his mate, coming to support him." "Now she joins in the dispute." "He is now on my tree, and his mate is even closer." "I have stopped knocking, so it seems to them that their rival has disappeared." "So all is well." "There's another drummer in the bird world, Australia's palm cockatoo." "His beak is no good as a drum stick, so he uses a wooden one." "(VIBRATING BIRDCALL)" "And that noise too is made mechanically, by an African broadbill." "It makes its call in the same way as children do when they blow across a blade of grass." "But instead of grass, the broadbill has specially strengthened and shaped wing feathers." "But, of course, most of the sounds made by birds come from their throats." "The calls and songs that you hear in a tropical rainforest, however, are very different from those you might hear in a European or North American woodland, and there's a reason for that." "The leaves in a tropical rainforest have smooth and shiny surfaces that reflect sound." "So a complex call up here would have its notes slurred and confused." "As a result, birds that live up here tend to have calls that are simple, short, and often very, very loud." "(SHRILL BIRDCALL)" "That's the loudest of all... ..from a bare-throated bell bird." "And this is a close rival, a screaming piha." "Toucans must also be close to the top ten." "Allthese birds callfrom high up in the canopy." "Lower down, where the foliage is less dense, the calls can be different." "For one thing, they can be longer." "(LONG DRAWN-OUT CALL)" "That's a currasow." "And this...a wattled guan." "A longer call, of course, can contain more notes." "A kagu in New Caledonia." "This is a female." "Her mate, some distance away, is listening." "The family wandered apart as they foraged, and now they want to get together again." "Her son has also heard the message." "So the adult pair are reunited, and they greet one another as usual with a visual display." "But their son is still out there, somewhere." "And once again, the family group is complete." "The calls of the kagu can be heard half a mile away." "But some birds need to communicate over even greater distances, and the best way to do that is with very low-pitched notes." "An American bittern." "An air sac in his chest acts as a resonator, so he starts by gulping in air and pumping it up." "This call carries for over two miles, even through the thickets of reeds." "And when the performance is over, the air sac slowly deflates." "If you can get out of the reeds, then your calls are less impeded." "The Australian musk duck does just that in order to broadcast his messages." "And the smooth surface of the water also helps to reflect the sound far across the lake." "The flap on his chin is a visual signalfor any birds that come over for a closer look." "However, if calls are directed to neighbours nearby, then they can become very elaborate." "This red bishop makes an almost constant stream of high-pitched notes as he hops around his territory." "And you can't get much more elaborate than this." "The extraordinary display of the Oropendula includes one of the strangest songs of all." "So how do birds do it?" "How, for example, can canaries sing continuously for minutes on end?" "Slowing the singer down, which also lowers the pitch of the notes, allows us to understand what's happening." "Between the notes it takes mini-breaths to replenish its air supply, and in full song it may do so 30 times a second." "A bird's voice box can also produce two different notes simultaneously." "It's not high in the throat like ours, but deep in its chest." "Low notes come from one side." "High from the other." "By alternating between high and low notes, even short songs can carry very complex messages." "And this is the champion." "The cowbird uses over 40 different notes in his songs." "Some of them are so high that they are beyond the hearing of many of us." "One again, if we slow the action down, we can hear what's going on." "The left side is producing the low notes." "And the right, the high." "Others are made by combining the sounds higher up in the throat." "It may take a cowbird two years to learn his song properly." "And it's important that birds should get their calls exactly right, for they can be just as significant in proclaiming identity as their uniforms." "Indeed, if a bird has a shy and retiring disposition, and lives in a secluded place like this English woodland, then its voice may be the only way that it can be recognised by another bird, or indeed by a bird-watcher." "There are two kinds of warblers here." "This is a chiff-chaff, fuelling up after its long flight from Africa." "And this is a willow-warbler." "To me it looks virtually identical." "But wait untilthey sing." "This is a chiff-chaff." "And this, a willow-warbler." "There's no mistaking who's who, as long as you can hear their calls." "But a bird's call can tell another bird more than just what kind of bird it is that's singing." "This patch of bush on a small New Zealand island belongs to a male saddleback." "He has held it throughout the year, and he knows who his neighbours are because their calls vary slightly." "And he can recognise each one individually." "And there he is." "Throughout the day he keeps in regular contact with his neighbours." "They each answer his call, and he can distinguish between them in the same way that we can distinguish between regional dialects." "A northerner." "A southerner." "And someone from the east coast." "If the right call comes from the right place, then he knows that his territory is safe, and he can happily go back to feeding." "But if the call is from a saddleback, one that he doesn't recognise, and if, as well as that, it comes from a completely new place, then he will react in a very different way." "And, of course, it's quite easy for me to make that happen." "I'm going to play him a recording of a saddleback from a different island." "His response is swift and very aggressive." "He comes down for a closer look." "He gives another warning." "This is a serious challenge to his territory." "It can't be tolerated." "Now, since his rival seems to be close by, he's making a visualthreat, displaying the brown patch on his back." "He is ready to fight, if only he could find who it is who needs fighting." "Well, I guess that's enough of that." "We'll leave him in peace." "To may of us, however, this is the most delectable of natural sounds." "It's an hour before dawn, it's spring, this is an English woodland." "All around, the dawn chorus." "It's so familiar that perhaps we take it for granted." "But there's a lot we don't know about it still." "As first light brightens, different kinds of birds, one by one, join the choir." "(INCREASING DAWN CHORUS)" "(MORE AND MORE BIRDS JOIN IN)" "Why should they all sing together at this time?" "Wouldn't it be better for some to sing later, by themselves?" "And that's not the only puzzle." "Why should it happen at this time of day?" "Well, at dawn it's still quite cold." "Insects are not yet up and about, so for many of the birds there's nothing to eat." "So they might as well sing." "There's another possible reason." "It's usually quite calm at dawn, and with no wind these messages willtravel far and still be recognisable." "The chorus is the equivalent of our early morning news, except that it is broadcast in fifty languages." "By listening to it, this wren knows which of its neighbours is still alive." "He knows where they are." "And if there are any new males on the scene." "Each kind of bird listens to its own particular section of the sound spectrum." "The song thrush broadcasts in the mid-range." "The wood pigeon's calls are somewhat lower." "Smaller birds, like the firecrest, use the higher frequencies." "These spring-time messages from male birds not only say "This is my patch", they also say to passing females "Why don't you come and join me?"" "Robins have now extended their usual songs to carry this additional message." "The male chaffinch has done the same." "He may sing his song over 500,000 times in a season." "By late spring, migrants have arrived from southern Europe and Africa, and are adding their voices to the chorus." "A wood warbler." "A pied flycatcher." "And a redstart." "His mate, like many, will be impressed by the originality and complexity of his song." "The male sedge warbler can produce fifty different notes and never sings the same song twice." "He's like a jazz singer, continually improvising, and different males develop different singing styles." "And this is perhaps the most lyrical of all European songsters." "A nightingale." "He may have three hundred different love songs in his repertoire." "And he will sing for a mate allthrough the night." "What bird has the most elaborate, the most complex, the most beautiful song in the world?" "I guess there are lots of contenders, but this bird must be one of them, the superb lyrebird of southern Australia." "He clears a space in the forest to serve as his concert platform." "To persuade females to come close and admire his plumes, he sings the most complex song he can." "And he does that by copying the songs of allthe other birds he hears around him, such as the kookaburra." "It's a very convincing impersonation." "Even the original is fooled." "He can imitate the calls of at least twenty different species." "He also, in his attempt to out-sing his rivals, incorporates others sounds in the forest." "That was a camera shutter." "And again." "And now a camera with a motor drive." "And that's a car alarm." "And now the sounds of foresters and their chain-saws working nearby." "That wonderful performance is only one example of the extent to which male birds will go in order to attract a female." "The range and sheer extravagance of their courtship displays can be quite astonishing." "The range of relationships between male and female that these displays lead to is also much more varied than you might suppose." "And it's that, the most crucial stage in the life of any bird, that we'll be looking at in the next programme." "(VARIETY OF BIRDCALLS)" "This lava gull in the Galapagos, like allthe rest of those birds, is sending a very clear message with its call." "It is saying, "I'm ready to mate and I have got a great place for a nest"." "Some birds send the same message but use an additional medium:" "not just sound but vision, as these frigate birds are doing." "Their visual signal is normally an inconspicuous patch of shrivelled skin on the throat." "It takes about twenty minutes to blow one up." "The females, who don't have a throat pouch, cruise by assessing what is on offer." "The size of the balloon gives them a good indication of a male's vigour, and therefore his desirability as father of their chicks." "A female takes a closer look." "Males who haven't yet got a nest keep a close eye on developments." "The female leaves, and one of the homeless males decides to make a challenge." "The throat pouch is an obvious target." "Tear that and its owner won't be able to attract anyone." "A new proprietor takes over the nest site and pumps up his balloon." "Success is swift." "She's found what she was looking for." "A male hornbill's brilliantly-coloured beak and wattle is also an indication of his fitness." "Having attracted a female's attention, he accompanies her on flights through the forest, and, at appropriate moments, he cements their relationship with a fewjudicious gifts." "A little fruit." "Males world-wide ingratiate themselves with females in this way." "Wattled guans do in the tropicalforests of Amazonia, and so do great tits in the suburban gardens of Europe." "Seabirds, of course, like fish, though it is stillthe prerogative of the female to decline a gift the first time it is offered." "Grebes like fish, too." "These are on a lake in North America." "But for grebes in particular, exchanging presents is only the beginning of courtship." "There's a lot of dancing to be done before the partners are sure they are meant for one another." "Their first routines involve repeating one another's movements." "Once they have got to know each other really well, however, they perform their pas-de-deux together with immaculate timing." "Their wings don't contribute much to their costumes." "Like those of all diving birds, they are short and stubby." "But the dancers make up for that with impressive footwork." "After the dancing, more gift-giving... weed from the bottom of the lake, a sample of what the couple intend to contribute when they make their nest together." "A male swallow-tailed gull also declares his intentions with a down-payment on the nest." "As a pair get to know one another better, they become sufficiently trustful to indulge in a little mutual preening." "Albatross behave in the same way." "These powerful bills are quite strong enough to injure anything or anyone that dares to interfere with the birds." "But now, as the pair sit together on their nest site, they are used to deliver the most tender of caresses." "What follows may seem like duelling... ..but actually it is, once again, a kind of dancing." "The sequence of movements is long and complicated." "If both partners perform without mistakes and in harmony, then, at last, there comes the most intimate act of all." "Mating in birds can be a very quick business, no more than a brief meeting of genital openings." "In albatross, it is unusually leisurely." "So pairs are formed and the union is consummated." "For most birds, the pair will now stay together for severalweeks, if not for severalyears." "In the case of these waved albatross in Galapagos, they will stay together for the rest of their lives." "And that, when you come to think of it, is very unusual." "Insects don't stay together, frogs and toads don't, lizards and snakes don't." "Why should birds?" "Well, the answer is...there." "No female bird can manage to fly around with an egg inside her - let alone several - for the days or weeks it needs to develop." "As soon as she can, she lays it." "But then caring for it is a majorjob." "And for these albatross, as for most birds, it's a job for two." "It would be nice to think that such a devoted pair were held together by mutual affection." "The evidence, I'm afraid, doesn't support that." "It's not so much the affection that one bird has for the other, as the concern it has for its own genes, which are in the egg the two produced together." "If, without jeopardising those, either bird could find a way of spreading its genes more widely, the evidence suggests they would take it." "Here in Jamaica, some male birds are far from faithful." "Flame trees, when in flower, produce great quantities of delicious sweet nectar." "It is the staple diet for hummingbirds, and Jamaica has many different species of them." "The male streamer-tailed hummer is a vigorous and aggressive creature, and a particularly strong individual willtake control of an entire tree." "Other males, of course, have their eyes on it." "But the resident male won't allow others near his flowers, even though you might think there is more than enough for everyone." "But he is not fighting just because he wants to drink allthe tree's nectar himself." "He is more devious than that." "The tree is the most prolific source of nectar around." "There are severalfemale streamer-tails in the neighbourhood, and they are busy building nests, which they do entirely by themselves." "They are relatively plain creatures, lacking the long streamer-like tails of the male." "There is so much nectar around that when the time comes they will be able to feed their chicks single-handed." "But the main supply comes from the flame tree, and, sooner or later, they allvisit it." "The male streamer-tailwaits for them to call." "As soon as one appears, he shows off in front of her with a special courtship flight." "He erects little tufts like ears on either side of his head." "She accepts him." "He goes back to wait for the next diner, while she pulls herself together and prepares for life as a single parent." "A good secure home can also be a very effective lure with which to attract a female." "Red-headed weavers in Africa often nest in colonies and when they do, the females, who have yellow heads, keep an eye on which male is building what before committing themselves." "This one is only just starting." "It's too early to judge his skill as a builder." "This looks promising, but perhaps it's stilltoo early to tell." "A lot of work goes into each nest." "It's very important that the weave should be tight." "If it's too loose, the eggs might drop through." "When one is finished and ready forjudging, the male perches hopefully beside it." "She clearly doesn't think much of this one." "This, however, is good enough to warrant an internal inspection." "If she accepts, she will add the lining herself." "But there are lots of females around, and as soon as she's settled in, he starts building another nest." "In fact, this particularly skilled and industrious male has already built three earlier nests, each of which now holds chicks that he has fathered." "Each female, by choosing him as a mate, has provided her young with the best genetic inheritance available." "And he, by keeping on building, has quadrupled the number of his offspring." "But some birds construct even bigger buildings to impress females, and to see the most spectacular of all, you have to come to the dense forests of the islands north of Australia." "Some females can be persuaded to mate for rewards that are more abstract than mere food and lodging." "There's a kind of bird here in New Guinea whose females select a male, not because he is a better meal-ticket, but because he is a better artist." "How else would you describe this wonderful construction except as a work of art?" "This is its creator, the Vogelcop bowerbird." "He has a passion for interior decoration." "His hut, almost big enough for me to crawl into, is neither a home nor a nursery." "It is a gallery in which he can display his artistic creations to visiting females." "These flowers come from a creeper that has only just started to bloom, great new material for anyone who likes colour." "And he loves it." "The iridescent wing cases of beetles also appealto him, and he has amassed an impressive collection." "But they are always in need of a little rearrangement to show them off to their very best advantage." "He calls to invite female visitors." "There are several such bowers in this part of the forest." "A hundred yards away, there is another one built by another male of the same species, who has a slightly different artistic sense." "If a female decides this is the best selection ofjewels, then she will mate with the owner." "So here, where living is easy, a female is not bowled over by practicalthings such as food or accommodation." "It's beauty that wins her heart, and beauty can be found not only in jewels but in costumes." "This is Bulwer's pheasant, and he's got spectacular wattles." "He's impressive enough when he is going about his normal business, but when she is around, he gets very excited indeed." "Impressive though he is, she is very critical." "He's not good enough, it seems." "Another pheasant, Temminck's tragopan." "His costume jewellery is even more elaborate." "And if you've got it, why not flaunt it?" "The male monal pheasant impresses his female with a greater expanse of unbroken iridescence than is possessed by any other species." "The argus pheasant has the largest of alltailfeathers, and wing feathers that are certainly as spectacular." "And what can rival the train of a peacock?" "The costume put on specially for courtship dances by the African widow-bird may not be quite as extravagant and unwieldy as those of the pheasants." "But the widow-bird displays by flying with his." "It's a hazardous business exposing yourself like this, even if you can fly." "You are making yourself an easy target for a hawk, and there are many around on these grasslands in Kenya." "Evidently the additional matings a male gets from displaying in this dangerous fashion make the risk worthwhile." "Up in the frozen north, on the Arctic tundra, life is altogether too rigorous to allow such extravagance." "Here males display in a more modest way." "The buff-breasted sand-piper." "No spectacular plumes for him." "But, nonetheless, he has quite an attractive armpit." "Flashes like these can be seen a good two hundred yards away." "A female has got the message." "She's definitely interested." "Now there are three females." "It's time to reveal all." "He reinforces his appeal with quiet clicking calls." "More and more females arrive." "Nearby, another male is having no success whatsoever." "Now there are four females with male Number One." "This hardly seems fair." "There must be something about Number Two's underwings that doesn't appeal." "So he comes over to where the action is." "The females don't know which way to turn." "But Number One won't allow anyone else on his pitch for long." "There's not room on this part of the tundra for two." "So competing for mates only too often leads to physicalviolence." "Scotland." "Here in the pine forests of the Highlands, fights between males are among the most violent of all." "The capercaillie is the biggest of grouse." "The arenas on which the males display are vigorously contested, and the best, in the end, is claimed by the most powerful male, who will defend it against any intruder." "He is so charged up, this being the breeding season, that he will display to almost anything, including me." "Now, now." "Now, now." "But here's a really serious rival." "He is being very reckless indeed." "Birds can get very badly injured in battles like these and even die from their wounds, but the rewards they are fighting for are very great." "This is the most important moment of their year." "The females tour the duelling grounds to select the bonniest fighter of them all." "And they seem to agree on who the champion is." "Runners-up are almost universally rejected by the females, while the winner attracts almost more mates than he can dealwith." "Some males make the job of the females in choosing between them easier by gathering together and displaying in groups." "And there is one bird in the canopy of the Brazilian rainforest here who has perhaps the oddest way of trying to impress the females." "It is called the Calfbird." "(DINOF BIRDCALLS)" "They compete with calls." "The sound is greatly amplified by air-sacs on their throats." "The skin surrounding the sacs is so thin that, as they inflate, you can see right through them." "This assembly is a hundred feet above the ground, high in the canopy, so high that very few people have ever seen the birds performing this extraordinary chorus, let alone film it." "The top male, with, presumably, the best voice, occupies the best site - a forked branch totally free of leaves." "The females look exactly the same as the males, as you might expect since the males are not using special costumes to compete with one another." "When a female flies down to the best branch, allthe males callwith renewed intensity." "More females arrive." "A female tells the male she has chosen him by giving him a peck on the neck." "She flutters to the other branch invitingly." "But he is concentrating so hard on his display that he doesn't seem to notice her." "She tries again." "That's the idea." "And then he notices a second female." "Call as they might, none of the males on other branches get a look in." "The Calfbird has a cousin whose males also display in groups." "They compete not with sound but with colour." "The cock of the rock." "The males assemble in groups of a dozen or so, perching low down on lianas, watching out for females and squabbling among themselves." "The female is dull-coloured." "She has no use for bright feathers." "Her arrival beside the display ground has an immediate effect." "The males flop down." "Each one owns a particular patch of ground, his court, on which he, and he alone, displays." "Each now has the problem of how to persuade her to land beside him, and a cock of the rock's idea for doing that is to bounce competitively." "They adjust their positions slightly to try and stay in a patch of sunshine if they possibly can." "Once again, a peck on the neck says "I'm yours"." "And once again, the male is not very quick on the uptake." "But he gets there eventually." "After this is over, she will go off and rear her chicks by herself." "Another female." "She makes exactly the same selection." "By gathering together, the males make sure that the females know where the marriage market is, but the price of doing so is that only one or two males will make a sale." "In just a few species, however, the males in a neighbourhood don't compete with one another, but collaborate to form a team." "This is the blue manakin." "He is the captain of his team and he whistles to summon the other members." "The team is complete and the show begins." "They are striving to prove that they are the best team of acrobats in the neighbourhood." "A female arrives." "She is going to get a close-up view of the performance from the actual dancing perch." "If she is sufficiently impressed, she will mate with the captain." "But why should the assistants help him?" "Because if something happens to the captain, one of them will have the chance to inherit his position." "It may not be a large chance, but it is better than performing solo and having no chance at all." "That's enough to show how expert they are, so the captain dismisses his assistants with another special call." "If the lady decides to accept him, she will mate with him nearby." "She willthen fly away and he willjust keep on dancing, hoping for another success." "He will never knowingly see his offspring." "But not all polygamous birds are so neglectful of their parental duties." "Here on the pampas of Argentina lives another male with many wives who takes his nursery duties very seriously indeed." "These eggs are all looked after by one single male." "And even now he is trying to entice another female to come here and add another egg to this huge clutch." "He's a Rhea, a South American ostrich, and he's mating with one of the group he has managed to attract into his territory." "Tomorrow she will lay." "The whole party now moves towards his nest." "He settles down to continue incubating." "And one of the females with whom he mated yesterday is now ready to lay." "She settles down within a yard or so of the nest." "An egg is on its way." "She leaves, and he rolls her egg into the nest to join the rest of his collection contributed by his other wives." "He may accumulate as many as forty of them." "Because the male has taken total charge of the nest, the females can be just as promiscuous as he is, and that female, having laid here, will now be going away to find another male with another nest" "to see if he will accept another egg." "That's unusual behaviour for a male, taking total responsibility for incubation and for chick rearing." "On the tundra of the Arctic, however, another species has taken this reversal of roles further still." "These are red phalaropes." "In almost any other species, you would be right to think that the bird with the brighter markings on its head and neck is the male." "And that judgment will be reinforced when you see two brighter birds fighting in front of a duller coloured one." "That's typical male behaviour." "But the truth becomes apparent when you see them mating." "It's the duller coloured one who mounts on the other's back." "It's the duller one who is the male." "That is the female." "He now goes away to the nest that he has already built." "The brighter coloured female comes back to him for several days thereafter, to mate again and to add more eggs to the nest." "While she sits, he stands aside." "Now it will be up to him, and him alone, to incubate the eggs and look after the chicks." "No one really understands why the phalaropes, almost alone among birds, have reversed the role of the sexes." "But mating openly with multiple partners is the exception." "In most species, both male and female are needed to bring up the young, so most birds after mating stay together as a pair, at least during the breeding season." "An indication that this is the basis of their relationship is that the sexes are broadly similar in appearance." "But even so, living as a pair doesn't preclude a little infidelity, now and then." "Perhaps the most bizarre behaviour of all takes place in the suburban gardens of England, and it seems that untilvery recently, nobody even noticed." "A young female hedge-sparrow, a dunnock, ready to lay." "This is her mate, Alpha, singing lustily, declaring his ownership of the nest and the territory around it from which he gathers food." "The pair often feed together, a devoted couple if ever you saw one." "He seldom lets her out of his sight, for she is not as faithful as she might be." "There's a third bird around - Beta, another, younger male." "He's not popular with Alpha and they're continually squabbling." "Sometimes the fights can get quite vicious and feathers fly." "But in spite of that, Beta stays around, skulking in the hedge." "Alpha, it seems, has the female to himself once more." "But she has got her eye cocked." "Beta is still in the hedge, calling quietly to her." "She joins him, and now, while Alpha is preoccupied with feeding, she and Beta get together." "Twirling her tail is an invitation, and in a split second they mate." "Beta flies away." "But now, out in the open, she is courting Alpha with that same old tailtwirling." "He takes precautions to ensure his paternity." "He pecks her genital opening." "And she eventually ejects a droplet." "It's Beta's sperm." "He persists for up to two minutes until his rival's sperm is all gone." "And now he mates with her." "It will be his sperm that willfertilise her eggs." "She has kept two males happy, both of whom will help to feed the young when they hatch, and Alpha has managed to ensure that he will be the father of the eggs she will soon lay, or, at any rate, most of them." "But it is here in the south east woodlands of Australia that infidelity reaches its most astounding, indeed, you might think, its ultimate height." "And it occurs among the families of this dazzling little bird... the superb fairy wren." "He is an attentive male, courting his female with little gifts of food." "But there are other males around, identifiable by the different rings on their legs." "One of them dances for her, flaring the blue fans on his cheeks." "Yet another male is also flirting with her." "And here's another." "And she selects one of them." "But her first, established male, is not around to see allthis." "He is visiting a female neighbour, and what is more, he's carrying a bouquet, a flower petal, something he never does at home." "And his flashy courtship behaviour pays off, too." "Now he is back beside his own nest and with his first mate, looking after the chicks that the nest now contains." "So the female fairy wren chooses the flashiest males to father her chicks, and allows her partner only just enough matings to ensure he helps to feed the family." "And the males, while they may have chicks in as many as six nests around here, may not have a single one in the nest that they actually tend." "They say it is a wise child that knows its own father, but that is never more true than in the bird world." "But extreme infidelity, like polygamy, is not widespread among birds." "Among swans, as amongst most birds, male and female stay together." "And by a combination of bonding with one another and driving away any who try to interfere with the partnership, they stay together." "Male and female conduct their courtship on equalterms, and when they are convinced they are compatible, they work together to build a nest." "Protected on most sides by water, and with a strong and aggressive mate to see off intruders, these swans will probably hatch their egg successfully." "But for many birds, they are now entering on the most difficult part of their lives." "They will have to employ all kind of ingenious stratagems if they are to raise a family, as we will see in the next programme in The Life of Birds." "These sooty terns are amongst the most aerial of birds." "Every one of them has spent the first three or four years of its life flying non-stop." "Feeding on the wing, swooping down picking up fragments of food from the surface of the sea, even sleeping on the wing." "But there is one thing that compels them to come down to earth." "This." "Flying with an egg inside the body, let alone a clutch of three or four, makes huge demands on the energy of a bird." "So every female bird in existence gets rid of that huge load just as soon as she can." "She lays it." "In places like this island in the Seychelles, where there are no land predators to steal eggs, it's safe for the sooty terns to put those eggs directly on the ground." "The birds sit as close to one another as they can without getting within the range of their neighbours' beaks, so they are equally spaced with almost mathematical precision." "Other kinds of terns have other ideas about where to put their eggs." "The fairy tern, for some reason, always puts them on a bare branch, though whether that is safer or more dangerous is debatable." "The females seem wildly optimistic." "A U-bend is one of their safer ideas." "The dimple left when a branch breaks away is not bad either." "But it seems a bit reckless to rely on a little dead twig like this, particularly when the trade winds blow as strongly as they do in the Seychelles." "The fact is that fairy terns' eggs are easily dislodged if left unguarded." "Skinks know that..." "..and so do the fodies, the local sparrows." "And that has solved the problem of how to crack it." "Yolk is provided by a female bird to nourish her chick as it develops inside the egg." "But it is equally good food for lots of other animals, so eggs are much sought after, and birds may have to go to great lengths to keep them safe." "Swifts living on the mainland have to take greater precautions." "The nests of palm swifts are minimal, but they put them in fairly inaccessible places, such as an isolated palm tree." "They stick a few feathers on the underside of one of its dangling dead leaves, using their spittle as glue." "To make sure that the egg stays in this flimsy hammock of feathers, they stick that to the leaf as well." "Changing places to take over incubation is a tricky operation when your nest is stuck to a vertical surface." "The power of flight enables birds to put their nests in places that are beyond the reach of land-bound creatures." "And there can be few more inaccessible spots than the rocks behind a great waterfall, like this one at Iguacu in South America, where Argentina and Brazil meet." "Swifts, once again, exploit their mastery of flight to go where no other bird can go." "Great dusky swifts roost for the night on the mist-drenched rocks alongside the falls." "But this is not a safe enough place for their precious eggs." "Theywill be deposited actually behind the curtain of water and to do that the birds must find the thinnest part of it." "Behind the curtain, they still have an awkward climb before they reach a place where it is possible to put an egg." "And this is it, a perpetually dripping ledge, just wide enough to accommodate a little muddy nest." "Many birds choose cliffs for their nest sites even when they are not screened by water." "Seabirds around the world use them." "But these aren't normal seabirds." "They're parrots and they are nesting on the coast of Argentina." "The powerful hooked beak that all parrots have and use for cracking nuts and gouging fruit is also an excellent excavating tool." "These cliffs are composed of a relatively soft sandstone." "No problem for a parrot." "Even so, digging a hole in them is hard work, so each hole, when it is finished, is a valuable property, and there is a great deal of competition and squabbling over any vacancy." "Sand-martins are not nearly so well equipped for digging." "They use their claws rather than their delicate beaks and they can only tackle sandstone if it is soft and friable." "But what they lack in equipment they make up for with energy." "Woodpeckers, of course, are expert carpenters and regularly chiseltheir nestholds in trees." "But this one is digging into softer material, an ants' nest." "The ants are furious, but they quickly get used to their lodger sitting in the middle of their mansion, and then they act as her guardians, attacking any intruder that tries to steal her eggs." "You might think that a hornbillwould have the most powerful excavation tool of all, but in fact its huge beak is a relatively delicate structure and no use at all as a chisel." "So hornbills have to find holes that are either natural or have been dug by others." "A pair do their househunting together and they are very choosy." "Perhaps this one will do." "With beaks over a foot long, these Great Indian hornbills have to have a pretty big hole." "But they like the entrance to be as small as possible to deter intruders." "Maybe this is just too small." "But she can just make it." "That's good." "The search is over." "This is it." "The male regurgitates a little food for her." "Now she has decided that this is for her, she won't leave again until her eggs are laid and hatched and the chicks well-grown." "She will depend entirely on her mate for food." "She seals herself in, narrowing the entrance with a plaster made of chewed wood, mashed food and her own droppings." "This will be her home, you could say her prison, for the next four months." "The majority of birds, though, don't nest in holes." "They buildtheir nests." "And builders, of course, need building materials." "Having no hands, but just a beak and at best one foot, seems bad enough, but these frigates on the Galapagos have got an additional problem." "Their feet are so short and their wings are so wide that they find it difficult to land, so they much prefer to collect their building material on the wing." "Boobies can settle and break off the branches they need for their nests." "Frigates can't, but they can steal." "So for boobies, getting building material from its source to the building site is the most difficult part of the whole business." "Stolen goods, it's true, but allthe more precious for that." "Eggs must not only be kept secure." "Once they start to develop, they also have to be kept warm and there is no better insulation than feathers." "Ducks and geese line their nests with feathers they pluck from their own breasts." "Other birds are not so self-sacrificing and prefer to use those that they find blowing about." "Tree swallows compete with one another in collecting them." "Miss... and a rivalwon't give you a second chance." "Even when you have got it you may not get away with it." "Tackling a bird without the feather is allwithin the rules of this particular game." "The golden-headed cisticola, a kind of Australian warbler, collects fibres and spiders' webs, not just for lining, but for stitching." "There is no more skilled a tailor in the whole of the bird world." "There's little problem about concealing this nest for the leaves she stitches together remain alive and green." "When she has finished, you will barely notice that they are bent together in a slightly unusualway." "The problem is greater when a nest sits on the bare branches of a tree." "The sitella, an Australian equivalent of the nuthatch, constructs its nest from spiders' webs and insect cocoons, and then covers the outside with rather coarser material." "Two pairs are building here, close to one another." "This one is in a tree covered in lichen." "And this, in one that has flaky bark." "The sitellas are not rigidly-minded birds with inflexible habits." "They use lichen to cover the nest in the lichen tree, and bark on the one in the flaky bark tree." "As a result, each is as well camouflaged as anyone could hope, and though both nests are plain for alito see, they are not easily recognised for what they are." "The apostle bird uses mud mixed with grass." "Nest building is a group activity." "A pair with their grown-up young from previous seasons work together." "It used to be believed that there was always a dozen in the team which is why they are called apostle birds." "Everyone seems anxious to contribute, and the team works so industriously and so harmoniously that their elegant cup is usually completed in a mere three days." "A bird's beak, it seems, can serve just as well as a plasterer's trowel, as a tailor's needle." "Some birds build nests not just as cradles for their eggs and chicks, but as lodging houses for the whole year." "Here in Namibia in Southern Africa lives the sociable weaver, and very sociable it is, too." "As many as three or four hundred birds will live in a single apartment block." "This haystack may be more than a century old." "It is so heavy that part of it has broken the branch that supported it and fallen to the ground." "And it's been built and maintained as a communal effort by allthe inhabitants." "Weavers are closely related to sparrows." "Though some of their relations do indeed weave, the sociable weaver builds in a rather simple way." "It just pushes straws, one by one, into this gigantic bale." "A large communal apartment block has a considerable advantage over small isolated nests when you live in a desert like this." "During the day it gets ferociously hot, but that thick roof of thatch keeps the apartments beneath nice and cool." "As the sun sets, the weavers, having been away feeding, come back to their homes." "At night, it can get very cold in the desert, as much as 7 or 8 degrees below freezing." "And then the thatch is probably at its most valuable, because it acts as insulation for the nest chambers, so that they retain much of the heat that they had during the day, and the birds that roost inside remain snug and warm." "Not allthe chambers are for nesting." "Some are not nurseries, but bedrooms in which several of the colony snuggle together for warmth." "So at last some kind of receptacle, simple or complex, is prepared for the egg, and it is time for the female to produce one." "The male frigate welcomes his partner back." "The crucial moment has arrived." "Mated female birds have been feeding intensively and their ovaries are much enlarged." "Each egg, emerging from one as a microscopic cell, is planted on a growing globule of yolk which will provide it with food." "It is fertilised by one of the sperm that has been lying awaiting it in the duct." "Albumen is wrapped around it to provide it with the water necessary for development." "It travels onwards for several hours." "Eventually, it reaches a section in the duct where there are glands that produce lime." "Here it lingers for 24 hours while the shell is added." "Pigment glands squirt little spots of colour on it." "And so, an avocet produces her egg." "The blotches and speckles on such an egg as this, laid on the ground, serve primarily to camouflage it." "These are the eggs of a golden plover." "They too are laid directly on the ground and are practically invisible;" "as indeed the bird that laid them will be once she settles down." "Plovers nearly always lay four eggs." "A few birds, however, have adopted a rather more risky policy." "They lay just two, or even one." "If they do that, they must lay it in a nest that is really secure, hidden, for example, deep in a burrow as the kiwi does." "Her egg is gigantic, the biggest laid by any bird, and a quarter of her total body weight." "It contains so much yolk that the chick will be fully developed when eventually it breaks out of its shell." "Expelling such an egg is obviously a huge effort." "The owner of this nest, a blue tit, adopts a very different strategy." "Her egg is tiny." "It weighs no more than a gram." "But she lays lots of them;" "one a day, day after day, for a fortnight or so, but the chicks after they hatch willface so many hazards that many will die and the survival rate in the end will be not unlike the kiwi's." "Few eggs are totally safe from hungry raiders, no matter how skilfully protected and artfully concealed they are." "Those lying in the bottom of these dangling nests of caciques in South America are certainly difficult to reach." "But the red-breasted toucan has a long beak." "This toucan's bill is just not long enough for these particular nests." "But the toco toucan has an even longer one." "The caciques are extremely agitated." "And with good reason." "If the caciques are to defend themselves against these powerful bandits, they will have to build even longer nests in the future." "In Australia, the prime egg thief is the currawong." "An unguarded nest." "An obvious target." "Another clutch gone." "Few eggs are safe from currawongs and the Australian birds, like birds everywhere, have developed many different strategies to try and foil burglars." "This is the nest of a yellow-rumped thornbill, but in fact this neat little cup is empty." "You might think therefore, that it has been robbed of its eggs." "But in fact this part of the nest has never had any eggs in it." "There's another entrance to the nest." "It's down here." "You might never notice it, untilyou watch the parent return." "The cup at the top is a dummy, and it seems that many currawongs have not yet discovered the fact." "This wren in Costa Rica has another way of protecting its eggs." "Its nest is pretty obvious... ..and equally obvious is another one close by, a wasps' nest." "The wren nearly always builds within a yard or so of these formidable insects." "It is a brave thief that risks being attacked by these." "But coatimundis are brave, sometimes to the point of recklessness." "Out here on the cold windswept plains of Patagonia there are no trees in which a bird could build a nest." "So plovers, like plovers everywhere, lay their eggs on the ground and trust their camouflage." "But if a stranger wanders too near it, one of the adults immediately responds." "Ahead, I can just see a bird crouching on her eggs." "And away she goes." "And now she starts a most bizarre pantomime." "This hardly looks like any kind of bird, and whatever it is, it seems to be crippled." "If I was a fox or maybe a hawk," "I might quite wellthink that this extraordinary performance represents an injured bird or maybe a little rodent." "Either way it looks like an easy meal and I might follow it and be led away from the nest." "And now she has taken me so far from her eggs that she can abandon her play-acting." "There is nothing the matter with her." "Having deflected me, she returns to her nest." "She has to go back to prevent her eggs getting chilled and the young within from dying of cold." "Keeping eggs warm, indeed, is a continuing problem for most nesting birds." "The maleo has a very labour-saving way of dealing with its heating problems." "It lives on an island in Indonesia." "In this one unshaded patch of the beach, the sand is kept so hot by the sun that the eggs will hatch by themselves, and the whole of the local maleo population know it." "The birds are accurate judges of temperature." "They have to be." "If they don't dig deep enough, their eggs will bake, and if they go too far, they won't develop." "That's probably about right." "Now allthat is needed is to fill in the hole." "And then they abandon it." "These eggs, up in Alaska, must be tended much more assiduously." "They belong to a snowy owl." "As she returns, you can see that the feathers on her belly are rather long and floppy." "There is even a glimpse of pink naked skin." "Her body has to be particularly well-insulated with dense plumage to prevent it losing heat in these near-freezing conditions, yet somehow she has to transfer some of that heat to these eggs." "This naked brood patch on her belly will enable her to do just that." "Her mate is away hunting for lemmings, not only for himself, but for her." "She cannot leave her eggs for more than a minute or two, so her mate looks after her, and he will have to do this for almost two months." "The chilly lakes of North America." "Here some birds trick others into looking after at least some of their eggs." "This female canvasback duck is sitting contentedly, incubating and minding her own business." "Out on the water, another female canvasback is mating with a drake." "The mated female has not yet built a nest of her own, so she makes her way to the one who has." "The sitting female clearly doesn't like this intrusion, but equally, she's not going to abandon her eggs." "The intruder pushes her to one side and quickly lays." "Sometimes the sitting bird doesn't seem to realise what has happened and accepts the egg." "But not this time." "There's a different kind of duck here, too." "It is a little smaller and the male has a redder head and neck, the redhead duck." "His female has also cast her eye on the canvasback's nest." "Perhaps she can try the same trick." "A canvasback egg is pale green, a redhead's white, so the redhead female tries to make hers less obvious by placing it in the middle of the canvasback's clutch." "The male redhead awaits." "And the deed is done." "The female canvasback leaves her nest for a meal and reveals that this last intrusion was not the first." "There are three white redhead eggs in her nest." "Meanwhile, the redheads sail away to make a nest of their own." "Distributing eggs between several nests, as both canvasbacks and redheads do, is like taking out an insurance policy." "And there are plenty of hazards on the lakes against which a duck needs to insure, if she possibly can." "Night is a time for burglary." "A racoon." "This clutch is finished, but there is still a chance that one or two of this female's eggs laid elsewhere will survive." "There really is sense in not putting allyour eggs in one basket." "Some birds, however, don't care for any of their eggs." "As parents, they are totally irresponsible and the most famous, of course, are the cuckoos." "This is a nest of an Australian fantail." "The two little eggs belong to the fantails, but the very big one is a cuckoo's." "It is so different that you would think that the fantailwould immediately recognise that something is wrong." "But watch." "The fantailfemale is around, but it's the male who comes back first." "He seems quite unaware that anything is wrong." "The female cuckoo is also keeping an eye on things." "The fantail has accepted the egg, and that will be disastrous, because when the bigger cuckoo chick hatches, it will push out the baby fantails." "Maybe cuckoos have only just started to do this and fantails haven't yet developed a defence." "In North America, the cowbird is also playing this game." "It has put an egg in the nest of a gnatcatcher." "It's slightly bigger, but very similarly marked." "Willthe gnatcatchers notice the difference?" "They have." "They are destroying their own nest." "There is no future for their own chicks in this one." "But nesting material is too valuable to waste, so they are going to start again." "They begin a new nest quite close by." "Day after day they labour, destroying the old and building the new." "And there goes the alien egg." "The cowbird has lost this particular duel." "Africa." "The duels are being fought out here, too." "This is a colony of lesser masked weavers and sitting in the trees nearby are, once again, cuckoos." "These are diederick cuckoos." "The cuckoos, if they can, will dump their eggs in the weaver birds' nest and leave them there for the weaver birds to rear." "And the weavers seem well aware of the danger." "They are taking precautions, adding long entrance tunnels to their globular nests as they must have been doing for many centuries." "The cuckoo watches for a recently finished nest in which a female has just started to lay." "There's one." "But the cuckoo is having a lot of trouble getting in." "In the past, cuckoo eggs have been frequently found in the nests of these weavers." "But none seem to be getting into thiscolony." "Maybe the weavers are beginning to make those entrance tubes just a little bit narrower." "The battle seems to be swinging the weavers' way." "Nearby, there's a colony of a slightly different kind of weaver, the marginally bigger masked weaver." "They don't put entrance tubes to their nests, perhaps because they themselves are nearer the size of a cuckoo, so any entrance they can get into, a cuckoo could also." "They have a different defence." "The colours of their eggs are extraordinarily variable, ranging from pure white to blue and speckled." "But any one cuckoo can only lay one kind of egg." "And it has no way of knowing what colour the eggs are in any particular nest." "So the odds are against the eggs matching." "Now I happen to know that this nest contains speckled eggs." "Let's see what happens if I put a pale egg in it." "Back comes the owner." "No doubt about who's winning here either, this time." "The battle between cuckoos and other birds is a continuing one." "The cuckoos developing new stratagems and perhaps finding new victims, and the victims finding new defences." "Soon, in those nests behind me, eggs will start hatching." "Most will produce young weaver birds, but some equally certainly, will be cuckoos." "Whichever they are, the young chicks will be faced with a whole set of problems that they have to solve if they are to grow into adults." "And the ingenious and sometimes touching way in which that is done is what we will be looking at in the next programme in The Life ofBirds." "The desolate wastes of the Antarctic - so cold that insects would freeze solid." "Volcanic springs in Africa - spouting water so hot and corrosive that it will strip skin from flesh." "The waterless deserts of the tropics - hundreds of square miles of baking sand." "The earth can be an inhospitable place, yet birds of some kind manage somehow to endure and survive all its privations." "Indeed, there is scarcely a corner of the globe that birds have not colonised." "Sandgrouse live in the sandy deserts of Africa, as barren a landscape as you can imagine." "Yet hidden in these sands are tiny seeds." "They were shed by plants months or years ago after a storm briefly dampened the desert." "The sandgrouse, by searching incessantly, manage to pick out severalthousand every day." "But they have to drink." "Waterholes are few and far between in this desert, and some birds may have to fly for as much as 50 miles before they find one." "And when they get there, all it is is a little puddle like this one in front of me." "After such a long flight, their thirst is huge." "But some must do more than satisfy their own needs." "They have left behind them, away in the desert, their newly-hatched chicks." "Chicks can't fly, but they too must have water... and the males willtake it to them." "They can't carry it in their crops." "They'll need allthat water to sustain themselves." "But they have extra tanks." "Their breast feathers have a special adaptation." "They're covered on their inner sides with a mat of filaments so fine that they absorb water like blotting paper." "And then they're off again on the long return flight." "A female is waiting for her mate." "It's roastingly hot, and with her are her chicks." "Here he comes, and the female makes way for him." "While the last chick struggles from its shell, the others cluster around and suck from his breast, for allthe world like puppies or kittens." "So one comparatively small adaptation of its feathers has enabled the sandgrouse to colonise a corner of the world closed to others." "The ground in the wake of one of the bush fires that regularly sweep across the grasslands of Africa seems initially just as parched as its deserts." "Yet the courser, a relative of the plover's, is a nomad who actually seeks it out." "Insects killed by the smoke and flames are easily collected." "So it has some attractions." "Yet it is also here that it chooses to nest." "This must be a long-standing habit, for its eggs are camouflaged to match the incinerated earth." "Since allthe scrub has been cleared by fire, the bird has the advantage of being able to see approaching predators." "Dawn on the shores of the Persian Gulf, and crab plovers, having fed on the edge of the sea, come back to their breeding grounds." "It will soon be so hot that the sand will be painfulto touch." "Yet this is where the crab plovers choose to nest." "Every other plover in the world lays its eggs in a simple scrape in the ground." "But not these." "They, in spite of their unsuitably long legs, have learned how to become burrowers." "They've discovered that, only a few inches below the surface, the sand is wonderfully cool." "There, a bird can sit on its eggs in comfort throughout the crushing heat of the day." "To feed, the plovers have to go down to the edge of the sea." "There, they can keep cool by bathing." "The African Rift Valley offers no such relief." "This steaming-hot water comes from volcanic springs and is so loaded with soda that around the margins of the lake it solidifies into white curds." "Yet flamingos come here in thousands." "The attraction?" "The salty, tepid water is full of algae and small crustaceans which the birds can collect, using their specialised beaks like filter pumps." "The fact that so few creatures can tolerate these conditions means that any animalthat can has the place to itself and so can proliferate in vast numbers." "That applies to the crustaceans and the algae in the water and also to the birds that feed on them." "For the birds, there is an additional attraction." "The soda-rich waters are so caustic that hunters such as hyenas, lions or smaller cats won't wade through them, so the centre of the lake is one of the safest places for a nest." "The flamingos pile the mud into mounds just high enough to be clear of any salt spray blown by the wind." "That, if it caked the eggs, would killthem." "But the heat is so extreme, the congealed soda so caustic, that sometimes a whole generation is lost." "Nonetheless, the success rate is still sufficient to maintain the size of the flocks." "This white desert is also hostile to life, but for a very different reason." "The crust that I am walking on is not soda." "It's snow and ice, and that too causes huge difficulties for birds." "Here in the Arctic, during the winter, such things that are edible are locked away beneath the snow and ice." "Nonetheless, a few birds manage to survive through this bleak season, provided they get help... ..from polar bears." "The bears will eat almost every part of a seal, their staple diet." "But they leave enough from their kills to provide scavenging gulls with a meal." "In summer, on the tundra, it's warm enough for plants to grow in the lakes." "There, spectacled eider duck swim and dive to collect insect larvae and worms from the muddy bottom." "But when winter comes, the lakes freeze and then the ducks vanish." "Untilvery recently, no one knew where they went." "The answer was found in 1995." "Hundreds of miles from the coast, they gather together on the surface of the sea, surrounded by ice." "There are no more than half a dozen such assemblies and between them they contain the entire world population of the spectacled eider." "The birds are so tightly packed and so continuously on the move that, within their huge pond, the water does not freeze over." "They can dive to collect food from the bottom of the Arctic Ocean 200 feet below;" "food that would otherwise be denied them by the sea ice." "In the Antarctic, at the other end of the globe, the winter can be even more severe." "Temperatures can fall to 80 degrees below zero and the gales blow at over 100 miles an hour." "Yet this is the time the biggest of all penguins, the Emperors, have to breed." "Having mated at the beginning of the winter, the females return to the sea, leaving the eggs with the males, who hold them on top of their feet to keep them off the ice." "Emperors are so big that there is not time in the short Antarctic summer for the chicks to grow into sea-going adults." "So breeding must start before the winter sets in." "The males cannot feed for four months." "Then the females will return, allowing the males to go down to the sea for a meal." "Meanwhile, in the continuous darkness of mid-winter, broken only by the Southern Lights, allthe male Emperors can do is endure." "The darkness perhaps doesn't trouble them unduly." "Penguins, after all, don't fly." "But most birds do, and they rely on their sight in order to navigate." "So, for them, darkness is a major problem, and no darkness is more complete than in a cave." "This is the Caripe Cavern in Venezuela." "(TREMENDOUS DIN)" "And here there is no natural light whatsoever, and yet, as I can hear from this deafening chorus of calls, there is a huge population of birds here." "How can they see to fly?" "Well, we have with us some very, very dim lights and an extremely sensitive low-light camera." "So if I turn this out..." "I can't see anything at all, and presumably the birds can't either." "But, hopefully, you can." "These are oil birds." "They're related to nightjars, and like them have large eyes that help them fly by the light of the moon and stars." "But in the depths of caves, even eyes like this are of no help." "Instead, the birds navigate by sound." "Their raucous social calls are augmented by high-pitched rattling sounds." "The echoes produced by these enable the birds to visualise their surroundings so well that they can unfailingly find their own nest." "In the evening, they fly out into the comparative brightness of the starry sky to feed." "They seek out the fruit of palms and laurels which have a strong fragrance, so the oil birds are able to find them by smell." "They are now in no danger of being attacked by hawks, as they would've been if they had not spent the day in the safety of their cave." "So all over the world, birds, by changing their habits or adapting their anatomy, manage to survive in the most hostile of places." "A century ago, a completely new kind of environment appeared on earth." "Nothing like it had faced the birds before in their entire 200 million years history." "Yet some species began to adapt to it almost immediately." "This is it, the modern city." "Sao Paulo in Brazil - a wilderness of glass and brick, concrete and steel." "And circling among the skyscrapers...black vultures." "There are plenty of ledges on these man-made cliffs to serve as nest sites, and the vultures have little hesitation in using them." "(PORTUGUESE FROM NEARBY RADIO)" "This devoted parent has brought back a crop-load to feed its chicks." "The adults have little difficulty in finding allthe food they need for themselves and their young." "There is, literally, tons of it around." "A short flight away, on the outskirts of the city, the rotting leftovers of a million meals are dumped daily, mixed with inedible refuse of all kinds, some of it actively poisonous." "Not many birds have either the temperament to tolerate such places or the digestion to cope with such food." "But those that have, swarm in huge numbers like flamingos on an African soda lake." "In the same way, when farmers bring industrial methods into agriculture and devote huge fields to raising just one particular crop and it particularly suits the taste of one particular bird, that bird willturn up in huge numbers to feast on it." "Waxwings." "They love these blueberries ripening in plantations in Florida, so they come in thousands to collect them." "If these assemblies reach plague proportions, then that is no more than a reflection of the intensive way in which man grows his crops." "Few other birds can manage to eat these large cultivated blueberries and indeed, even waxwings sometimes have a little trouble in doing so." "Crows have become highly skilled at making a living in these new urban environments." "In this Japanese city, they have devised a way of eating a food that normally they can't manage." "Dropping a nut from a great height onto a hard road does, sometimes, crack it." "But some nuts are particularly tough." "So the crows have devised a better way." "Drop it among the traffic." "The problem now is collecting the bits without getting run over." "So some birds have refined their technique." "They station themselves beside pedestrian crossings..." "..wait for the lights to stop the traffic..." "..then collect your cracked nut in safety." "City life may offer birds attractions that are rather less obvious than just food." "This is the centre of Glasgow, 5 o'clock on an autumn evening." "For half an hour, thousands of starlings put on a spectacular display of formation flying over the darkening city." "Why they do this we don't really know." "Maybe it is to get to know one another, creating some kind of team spirit, for they tend to spend the winter in parties." "Maybe it's because there is safety in numbers when trying to avoid predators such as hawks." "When it's too dark for aerobatics, they come in to roost." "Such assemblies may be information centres." "Birds that fed welltoday will head back tomorrow to where they know there is food." "And the hungry ones willfollow them." "Here in Europe, towns are also attractive because it is a little warmer than out in the countryside." "You might think that this is just about the last place that a bird or any other animal would choose to sleep." "This is an oil refinery on the banks of the Amazon River in central Brazil." "Just across the water, there's a lovely virgin rainforest, yet here - well, just look and listen." "A fine mist of acrid droplets stings your eyes." "The noise hurts your ears." "Yet promptly at 5 minutes past 6 o'clock every evening, there is an invasion." "Purple martins." "Stay still and they will settle within inches of you." "Why they come here in such numbers is a mystery." "It can hardly be that they seek warmth in this muggy tropical atmosphere of central Brazil." "They don't feed here." "Perhaps it is because there are fewer hawks around to harry them than in the forest." "But whatever the reason, come they do." "In March, however, many of them will migrate north to the United States, and there they take up residence in very different homes." "A small lakeside town in Pennsylvania." "This luxury tower block has accommodation for over 40 adults and 200 youngsters." "Each apartment has all modern conveniences." "It can be wound down regularly by the local people and the shelf brought out to make sure that the young are fit and don't need help with the housekeeping." "In fact, these apartments are so luxurious that these days, purple martins don't nest in natural sites any more." "The purple martin has become totally dependent on human beings." "It's said that the tradition was started by the people native to this part of North America," "Choctaw and Chickasaw Indians, who were glad to see the birds when they arrived each spring and hung out gourds to encourage them to nest around their settlements." "Today, over a million people in the United States offer hospitality to purple martins in this way." "It seems that those of us who live in towns and cities feel increasingly cut off from the naturalworld that lies beyond our buildings and so we treasure any contact we can find with wild creatures." "Certainly, an affection for birds is shared by all kinds and conditions of people all over the world." "In Arizona, Jesse Hendrix is particularly devoted to hummingbirds." "His home lies on the migration routes of several species." "The black-chinned is one of the most common." "In spring they travel up from Mexico on their way to nest as far north as Montana and British Columbia." "Then in autumn, he sees them again on their way back to their winter quarters in the warmth of the south." "Some of them have been fitted with leg-rings, so he knows the same birds visit him each year to drink from the same feeder." "It's possible that many now vary their routes to make sure that they pay a call at such a reliable restaurant." "At the height of the migration, he may be visited in a single day by about 9,000 different birds." "And every day he provides his customers with over 13 gallons of sugar water." "Meals like these must surely make the difference between life and death for many of the little rufous hummingbirds which, on leaving Jesse's fuel station, have stillto tackle the last stage of their 2,000-mile migration across the Bay of Mexico" "in one single 600-mile non-stop flight." "The very regularity and predictability of birds can be part of their appeal." "..it is quite unpredictable." "We can neverbe terribly certain where..." "On Philip Island, near Melbourne, Australia, people come from all over the continent to watch a regular evening parade." "Little penguins, the smallest of the family." "They fish for pilchards and anchovies out at sea during the day, and every evening come ashore together to return to their nest burrows, following paths that have probably been in use for thousands of years." "Scientists started to tag them back in 1968." "It's the longest-running bird study in the whole of Australia, so by now they are well used to being stared at." "Human beings over the last century have built houses for themselves along the penguins' beach, but that hasn't deterred the birds." "Two half-grown chicks are awaiting their evening meal." "And the human residents are only too delighted to have such engaging lodgers with regular habits living beneath their front doorstep." "Humanity's impact on the bird world, however, has not always been so helpful." "Birds reached allthe islands of the Pacific a very long time before people did." "Small birds such as white-eyes are not very powerfulflyers, but they probably made the sea-crossings inadvertently, carried by storms." "Once on land, they and others, like fantails, found insects to eat which doubtless had made the journey in the same sort of way." "Honeyeaters found plants in bloom from which they could drink nectar." "And pigeons found fruit." "But when people sailed across the sea, they brought animals that by themselves could never have made the journey." "This is the small island of Guam that during the Second World War became a major military base." "Some time in the 1940s, brown tree snakes from New Guinea appeared here, brought accidentally by ships." "Tree snakes hunt birds, and Guam's white-eyes, flycatchers and fantails, having no experience of predators, had no defence against them." "Today, Guam is an island without birds." "Species that evolved here and differed from any elsewhere have now gone for good." "Insects and spiders, without birds to keep their numbers in check, have proliferated." "And the forests have fallen totally silent." "These New Zealand forests have also been invaded by foreigners - foreigners that have caused great problems for the local birds and, in particular, the kaka, the local parrot." "These invaders are surprisingly very small." "They are European wasps, but their effects have been devastating." "Kakas eat a great deal of vegetable food - fruit and seeds and nectar." "But they also feast on honeydew, a sticky fluid excreted by insects that live beneath the bark of these trees, drinking sap." "Female kakas rely on this high-energy food to bring them into breeding condition." "But the European wasps found honeydew much to their taste as well." "The kakas are unable to compete, and they are already under severe attack from introduced predators such as stoats." "These latest insect invaders may well be the final competitors that eliminate the kaka from these forests." "But the greatest destruction of the world's birds has been inflicted by human beings." "The hula, which once lived in New Zealand's woodlands, was hunted precisely because it was rare, and was finally totally gone in 1907." "The great auk, a giant flightless relation of the razorbill that lived in the islands of the north Atlantic, was hunted and exterminated by the middle of the nineteenth century." "The dodo, a pigeon that, safe in its island sanctuary of Mauritius, also evolved into a flightless giant, was easy prey for hungry sailors." "They exterminated it by the middle of the seventeenth century, less than 200 years after men first set foot on their island." "It's not only on islands that birds are vulnerable to changes brought by humanity." "150 years ago, prairies like this in the United States were home to flocks of birds 2 to 3,000 million strong." "They were so big they darkened the skies and took two or three days to pass." "They were what was probably the most numerous bird that has ever existed on earth - passenger pigeons." "Their numbers were so astronomic that no one considered them as anything but pests, nor could imagine that they would ever be in danger of extinction." "But a combination of hunting and changes to the landscape brought by farming destroyed them." "The last wild passenger pigeon was sighted in 1889, and the last survivor of all, a lonely female called Martha, died in Cincinnati Zoo in 1914." "Birds are still being slaughtered in huge numbers even today, particularly when there are economic reasons for doing so." "Dickcissels in Venezuela also swarm in flocks millions strong." "The whole world's population comes here in winter, and they sometimes roost in only three or four sites." "Should anything happen to those sites, the dickcissels could go the same way as the passenger pigeon, and they are a very serious pest." "Farmers know how to dealwith insectpests." "They spray them with poisons." "So the same technique is sometimes used against dickcissels, in spite of the fact that it's against the law." "The birds, recorded here by amateur video, take several days to die." "Yet humanity, so often in the past the mindless and merciless exterminator of birds, can sometimes become their guardians." "Here, in a remote part of Tasmania, a mining family has become the saviour of the orange-bellied parrot." "For years, they've been putting out food daily on a bird table, and these parrots became their best customers." "A century ago, there were certainly many thousands of this bird here and in south-east Australia." "But in the 1940s they began to decline." "The cause was probably competition from introduced seed eaters such as sparrows, goldfinches and greenfinches." "Furthermore, 70% of their mainland habitat was destroyed." "European cats living wild in the bush also took their toll." "Now, not more than 200 survive, and nearly all of them are here during the nesting season." "The area is very isolated, but bird-watching enthusiasts are very enthusiastic." "They come not only from mainland Australia but from all over the world to see these rarities." "A special observatory has been built for them." "And special nest boxes within binocular range have been put up for the parrots." "So, although the orange-bellied parrot is stillfew in number and therefore a very rare bird, it's seen by thousands, and, for the moment at least, seems safe in its remote sanctuary." "This kestrel comes from Mauritius, the scene of one of mankind's earliest annihilations, of the dodo." "In 1974, only four known individuals survived." "Today, there are 540 on the island." "They were saved by conservationists, who took young from their nests and reared them by hand, so allowing the adults to lay again." "Today, each nest is still being carefully monitored." "The bird is now totally self-sufficient in the wild." "Just two free-flying pairs are given extra food as part of a long-term study." "The present population is nowjust about as many as the island can sustain." "The Mauritian pink pigeon was thought to be totally extinct until a small colony was found in the mountains." "But that dwindled to just nine known individuals." "They too were persuaded to breed in captivity." "The young are taken from nests and given to barbary doves to rear, so releasing the adults to breed again." "Now, pink pigeons are being released in three different parts of Mauritius." "Feeding programmes have also been started to help these new populations establish themselves." "Today, the birds are breeding regularly, and the population has risen from 9 to over 300 in just 7 years." "The Mauritian echo parrakeet was once the world's rarest parrot." "Now, using similar captive breeding techniques, there are 20 in captivity and 80 in the wild." "The island of Mauritius, once a black name in the history of humanity's relationship with birds, has become one of the showplaces of species conservation." "In West Africa, in Cameroon, villagers celebrate the forest beside which they live, and in particular one of its birds." "Bannerman's turaco." "Many of the creatures of the forest, such as the elephant that also figure in this celebration, have long since disappeared." "The turaco, however, still survives, though in the whole of this forest there are only about 4,000 pairs, and it lives nowhere else." "For decades the forest has been felled to make way for fields in which the people can grow their food." "It's now only half the size it was 30 years ago." "Yet the people also know that they depend on the forest for water and firewood, for medicine and for meat." "So now, a balance has been struck." "The traditional beliefs of the people have been harnessed to come to the forest's defence." "The masked figure of Mabu, their spirit guardian, accompanied by the village elders, regularly patrols the margins of the forest." "Stakes are planted to mark the point beyond which no tree may be felled." "The turaco has become a symbol of the villagers' regard for their environment." "And Mabu is now in league with international bird conservation bodies who are also concerned about the survival of Bannerman's turaco." "In North America, there are other masquerades, to protect a bird that is even rarer than the turaco." "A whooping crane chick learns to feed, encouraged by the gestures and calls of its human foster parents." "In 1945, only 16 whooping cranes existed." "Today, there are 300, thanks to captive breeding and the patient rearing of chicks by hand." "(SPEAKING QUIETLY) And this is surely one of the most extraordinary hand-rearing devices yet invented:" "a whooping crane adult hand glove puppet with a trigger inside so that I can operate the beak." "I'm speaking quietly because behind each of these doors is a whooping crane chick, and it's very important that they don't get used to the sound of human voices at this early stage in their lives." "It's even more important, of course, that they don't see human beings, which is why they are fed with this glove puppet." "Here at the International Crane Foundation in Wisconsin, they believe that, were the chicks to be fed by humans directly and visibly, they would risk becoming humanised, so that when they became adult they wouldn't be able to breed with their own kind." "As they grow, the whoopers lose alltheir brown plumage and replace it with white feathers." "They must now learn how to use them in flight." "And once again, they have to be shown the sort of thing they must do." "Away to the west, in Idaho, a farmer with a passion for cranes, Kent Clegg, has also been rearing a small group of whooper chicks." "He has a mechanised way of persuading his little flock to fly." "He has reared them in a quite different way, initially in small groups, which he believes will avoid humanising problems." "He then taught them to follow him." "Now he has put them together with the young of a commoner, smaller species, sandhill cranes." "They are the all-brown ones." "So the little mixed flock has become confident in the air." "There's one further problem:" "whooping cranes are migratory." "In the past, some used to overwinter in the United States, but many in the autumn would fly south to New Mexico." "If these birds were to remain free, they might try to do the same thing." "But how would they know which way to go without their parents to guide them?" "And how would they find somewhere safe to feed when they got there?" "Well, that problem is being tackled too." "Kent Clegg is planning to lead them there himself, in his microlite." "Birds were flying from continent to continent long before we were." "They reached the coldest place on earth, Antarctica, long before we did." "They can survive in the hottest of deserts." "Some can remain on the wing for years at a time." "They can girdle the globe." "Now, we have taken over the earth and the sea and the sky, but with skill and care and knowledge we can ensure that there is still a place on earth for birds in alltheir beauty and variety..." "..if we want to, and surely we should."