"I'm looking at one of the most striking and instantly identifiable animals in the world." "A single one is worth about a million pounds." "Famously fussy in their feeding," "less than a thousand still survive in the wild." "Millions are spent on conserving them, and yet increasingly it's the case that if you want to see one you've to come to a zoo, like this one in Atlanta." "It's a giant panda." "When it comes to food, the giant panda is the ultimate specialist." "It eats bamboo and virtually nothing else." "Not many animals can live on such a diet." "Bamboo is tough, fibrous and very indigestible." "With no competition, pandas thrived, until the bamboo forests in their native China started to disappear." "Then with no other food to fall back on, their population crashed." "So the giant panda lives its life on the edge." "There are other feeding strategies." "Instead of being a specialist, you can be a generalist, an omnivore, prepared to eat pretty well anything you can find, animal or vegetable." "That strategy has led to some animals that are the most successful and charismatic of all." "What does it take to be an omnivore and who are they?" "Omnivores are the most adaptable animals in the world." "There's no better example than the North American racoon, which is as varied in its diet as the panda is specialised." "This remarkable mammal has adapted to more types of habitat than almost any other." "The skills that have enabled it to do so are many, but there's one which it shares with all omnivores:" "the ability to make the most of any opportunity." "The racoon owes much of its success to its inquisitive nature." "But it also has a special trick up its sleeve... extremely sensitive hands." "Touch is the racoon's most powerful sense." "To process the information it gets from its hands, it uses an unusually large proportion of its brain, about the same as humans use for sight." "Scientists now believe that a racoon, through touch, can construct a picture of its surroundings that is as complex as that which we perceive with our eyes." "You might say that the racoon sees with its hands." "It can feel the difference between a rock and a clam in a split second." "If it touches a crayfish, which is armed with powerful pincers, then this "second sight" is clearly very valuable." "Their extraordinary sense of touch is not affected by temperature." "Unlike human beings', racoon hands retain their sensitivity even in the coldest water, allowing them to forage in rivers and streams whatever the season." "Racoons have been around for nearly two and a half million years, but the first opportunists appeared much earlier than that." "Being able to eat anything was not the basic condition of mammals." "The very first of them, contemporaries of the dinosaurs, small insignificant creatures, had such tiny teeth they probably ate little but insects." "Specialist omnivores did eventually appear among the prehistoric mammals." "One lived here in South Dakota, though then the climate and vegetation was very different." "It's called Dinohyus, and some experts have likened it to a kind of killer warthog." "This animal was as big as a rhino." "It had a large hairy crest running down its spine, a long snout and a formidable set of teeth." "Dinohyus died out about twenty million years ago, but its teeth can tell us what it ate." "At the back, he had massive flat molars that could grind up almost any kind of vegetation." "It wasn't a specialised vegetarian, because the teeth at the front didn't have the sharp chisel-like teeth that an antelope has." "Neither was it a specialised meat-eater, because the teeth in its middle jaw are not the slicing, sharp, dagger-like teeth that a lion has." "Nonetheless, these are pretty formidable." "So are the big tusks at the front." "What you have here is a generalised tool kit that enabled the animal to deal with almost anything." "Dinohyus may be extinct, but teeth like these are typical of all living omnivores today." "The forests of Sulawesi in Indonesia are haunted by a rare and elusive animal, almost as prehistoric-looking as Dinohyus." "To find food here, this animal uses not touch but another "supersense", the one possessed by all omnivores." "The thud of a large pangi fruit hitting the ground might attract the attention of an animal nearby, but sounds don't travel far in these thick forests." "Scent, however, can drift on a breeze and be detected from great distances by an animal with a really sensitive nose." "This creature certainly has that." "It's a babirusa, and its sense of smell is probably as good as that of any omnivore alive or dead." "There are several here, attracted by the smell of the ripe pangi." "Males have bizarre teeth in their top jaw that grow upwards, right through the flesh of its snout." "The size of these tusks is a good indicator of strength, so they determine who gives way to whom." "The pangi fruit may smell good, but there's a problem - it contains a poison." "The babirusa, however, knows how to deal with that." "It visits a clay lick." "Clay containing the right sort of medicine is not common, and these licks are few and far between." "A large one like this attracts babirusa from miles around." "These are the only places where this rare animal is seen in any numbers." "The clay contains a particular mineral which helps to neutralise the toxins in the pangi." "Babirusa, like most omnivores, live in relatively small groups, for they specialise in picking up odd bits and pieces, which seldom occur in sufficient concentration to sustain a herd." "So the clay lick, for the babirusa, is a time when individuals that otherwise lead lonely lives get to know one another." "Young males get a chance to test their strength." "The nose, for any pig, is its greatest asset... a multi-purpose tool which not only locates food but digs it up as well." "Wild boar, the European cousin of the eccentric babirusa, are unrivalled foragers." "They are the least fussy of feeders." "Worms make a tasty snack, but pigs know there's plenty of other food here." "It's just a question of finding it." "Their memories carry the smells and images of all sorts of things that they've previously eaten and assessed." "Keeping an open mind means that nothing will be overlooked." "Certainly not a decaying pigeon." "Foraging in the woodland is not difficult in summer, but what happens when the ground is hidden beneath a blanket of snow?" "Food is now very scarce." "The carcass of an animal killed by the hardships of winter is a valuable prize, but the pigs must continue foraging in their normal way if they're to maintain their strength." "They're not just ploughing through the snow at random." "They're still guided by their nose, for smell travels through snow." "And there's an interesting smell...right here." "And here." "By following their noses, pigs are able to keep active throughout the winter." "Other opportunists use a different tactic." "They spend the winter asleep in underground dens and only appear when spring brings better weather." "This is the Asiatic racoon dog." "Its legs are so short that it has difficulty moving through snow, which may be one reason to hibernate." "It too eats almost anything." "The females need to do so, for they produce large litters, and supplying all her babies with milk makes great demands on the mother." "She's produced fifteen pups." "They all need to put on considerable weight to survive the winter, and they'll only be helped by their parents for eight short weeks." "Their first food, of course, is their mother's milk." "But very soon they need solid food as well, and that too has to be provided by Mother." "While she goes off to forage, the male stays to look after the pups." "Surprisingly, given the size of his family, he does virtually nothing to help feed them." "The female is coming back." "She's caught a small rodent." "Unlike many canids, they do not regurgitate food for their babies, and, as mouths hold less than stomachs, this limits the amount of food she can bring back on one journey." "As a consequence, she has to provide her cubs with milk for twice as long as any other dog does." "She'll make a number of journeys every day, but most things she brings are only enough for a single pup." "This time she's brought an egg." "The pups haven't yet learned how to deal with such a strange object." "Is it worth eating, and if so, how?" "Yes, it is!" "And the pups won't forget." "Before long, they must start foraging for themselves, with their parents alongside to give guidance as to what is edible." "They don't always get it right." "They have to learn fast, for each will have to get as fat as its mother if it's to survive the long sleep through winter - and not all the litter will do so." "Racoon dogs store food as fat, but another omnivore has a different tactic." "Chickens, one of mankind's favourite prey, which he keeps in unnatural concentrations to provide himself with fresh meat and eggs all year round." "In farmyards like this, chickens are easy targets for any opportunist determined enough to find its way in." "If there's a weak link in the defences, a fox will find it." "Foxes are frequently blamed for killing more than they need, but do they really deserve such a bloodthirsty reputation?" "No." "A fox will not waste what it kills, providing it's not disturbed." "However, it must act quickly if it's to make the most of such an opportunity." "Few realise that foxes bury their surplus food." "They're saving it for when times get tough." "A vixen will bury carcasses all over her territory." "Later she will use her memory and keen sense of smell to find them again and dig them up." "The fox is not a wanton killer, but an intelligent opportunist who thinks ahead." "Some opportunities are both brief and seasonal." "There's an abundant source of food in this cave, but only for a few weeks, and it lies right in its far depths." "Down here, it's totally dark, and we can only see what goes on by using infra-red cameras." "Darkness is not a problem for bats, who navigate by echolocation." "For any other animal, getting around down here is a serious challenge." "And there's another major obstacle." "Droppings produced by the vast assemblage of bats creates an atmosphere thick with ammonia and fungal spores that can be fatal to those that inhale them." "This guano accumulating on the floor of the cave sustains more than fungus." "There's a living carpet of flesh-eating beetles and larvae, which together make short work of anything they can get hold of." "This is about as hostile an environment as you'll find anywhere on the planet." "Yet that doesn't deter an enterprising and unfussy opportunist - the skunk." "Indeed, skunks seem almost at home here." "They even indulge in a little courtship, as can happen when a male blunders into a female in the pitch dark." "What is it that tempts them down into this repellent place?" "The answer is baby bats." "At this age, they are unable to fly, and in such a jostling crowd many lose their footholds and fall." "On the ground, the babies are in great danger." "The skunks can see nothing whatever, so the fallen bats may survive, if only they can regain the safety of the rock wall." "But so many bats fall that the skunks are likely to blunder into enough to make their visit worthwhile." "In the total darkness, the skunks can't be sure which end of the bat is which." "So to avoid getting bitten, they roll the bat on the ground to subdue it." "It's not just skunks that make the most of this macabre seasonal offering." "The touchy-feely racoons are here too." "It might just be the place for an opportunist that can see with its hands." "Exactly which sense the skunks and racoons use to find the bats in the pitch-black cave, no one really knows." "Smell seems unlikely, given the overpowering stench of ammonia." "How could a skunk or a racoon possibly hear the distress calls of a single baby bat above the deafening squeaks of several million others?" "The most likely answer is that they use a combination of touch and luck." "Both racoons and skunks must rely on, literally, bumping into the bats." "This bonanza will only last for about a month." "Then these opportunists will have to revert to more reliable sources of food." "Elsewhere in the world, however, making the most of seasonal abundances is a way of life." "Up here in Alaska during the summer, a whole succession of different food becomes available." "There's a spectacular animal here prepared to sample each of them." "No one dish remains available for very long, so you have to make the best of it while you can." "Top of the menu right now is...salmon." "It's the favourite food of the largest and certainly the most formidable of all omnivores - the grizzly bears." "Salmon are plentiful now, but six months ago, in the middle of winter, conditions were so harsh that it was impossible for a large animal to get enough to eat." "All a bear can do then is to sit it out and try and conserve as much energy as possible." "To see how they cope with these enormous seasonal changes, we must go back six months." "In October, grizzly bears went into a deep sleep, their temperature dropped several degrees and their pulse rate decreased to about ten beats a minute." "They don't eat, drink or defecate, but they do occasionally stir." "During hibernation, a bear burns up almost a million calories... virtually emptying its energy reserves." "By spring, they will have lost nearly a third of their bodyweight." "To avoid starvation, they must now find food - and quickly." "Their diet will be driven by a clearly defined seasonal cycle." "Now, in April, they eat roots." "Roots are followed by grass." "It's easy food, but they'll quickly move on to the next course if something really big shows up." "This whale carcass could last them a month." "And by May, fresh meat is on the menu." "Mid-summer, and they're back on the salmon." "This bear has been out of hibernation for about four months." "Surprisingly, it's not gained any weight." "Indeed, it may even have lost weight." "But if it's to survive the coming winter, now is the time when it really has to pack on the pounds." "Salmon, one of the most important sources of food for bears, is now available in quantity, as the fish migrate in thousands up the rivers to spawn." "Chasing them uses a lot of energy, but the rewards are great." "Salmon are rich in protein and fat." "So valuable is this source of food that a bear that hasn't got a salmon of its own will spend considerable energy trying to steal someone else's." "In a good salmon year, a bear can catch a dozen a day." "This gives a huge boost to its energy reserves." "But it's not just about numbers." "Some parts of the fish are more nourishing than others." "If there are lots around, the grizzlies will eat only brains and caviar." "This behaviour piles on even more calories." "Even when there are no salmon to be caught, bears can still find food out on these estuaries." "Like pigs, they have an extraordinary acute sense of smell, and that can guide them to food even beneath the surface of the sand." "Clams." "How on earth can an animal with massive paws and huge claws manage to open and extract meat from a tiny shell like this?" "The answer is...with surprising dexterity." "Clams may look small in the paws of a grizzly bear, but they're still worth all that effort." "Early autumn - two months to go before hibernation, and the bear's appetite steps up a gear." "A seasonal change in the bear's physiology now allows him to eat continuously without ever feeling full, a huge advantage during the berry season." "They may eat as many as 200,000 berries a day." "And that gives the next big boost to a bear's energy reserves." "But at this time of the year they'll eat whatever they find." "After three months of counting calories, they're back in shape." "For these grizzly bears in Alaska, the real test is about to begin." "With luck, they will have put on enough weight to enable them to survive the coming five to six months of winter." "They will only have done so by being extremely unfussy feeders." "The lifestyle of a generalist may seem a good strategy, but from an evolutionary perspective, there's always the temptation to specialise." "In India, there's another bear happy to tackle anything remotely edible it comes across." "But that is only for half the year." "This bear, the sloth bear, has started down the road to specialisation." "Inside this mound of clay lies a huge quantity of food, and the sloth bear has just the right equipment to collect it." "It has particularly large claws, perfect for breaking into these sun-baked termite mounds." "It's worth the effort, for just one colony may contain a million individuals." "The termites' first line of defence has been broken." "Faced with such a large and destructive predator, there's little the soldier termites can do to drive the bear away." "As the termites swarm over their smashed mound, the bear hoovers them up." "But the greatest prize are the larvae that lie inside the nest." "The bear has other adaptations as well as big claws." "It's lost its two front teeth, so by pursing its floppy lips into a tube, it can suck insects directly into its mouth." "At the end of its snout, there's a flap that prevents dirt and dust going up its nose at the same time." "But the sloth bear may be heading for danger;" "the same danger that may before long exterminate its cousin, the giant panda." "For the moment, however, there's no shortage of termites, and the sloth bear has still not become as wholly reliant on them as the giant panda is on bamboo." "Just as humans have had an impact on the giant panda and its food, so they have on the sloth bear." "In India, sloth bears live alongside people, and conflict between the two is common, resulting in hundreds of maulings every year." "During the day, bears take refuge in areas not used by people." "Sloth bears may not compete with cattle for food, but land turned to grazing reduces the bears' termite harvest." "Loss of natural habitat has had a serious impact on wildlife across the globe, but, ironically, man-made habitats have provided new opportunities for many omnivores." "The modern city, a seemingly sterile world of concrete, steel and glass." "It must be one of the most difficult places for a wild animal to make a living in." "It would be, if not for the extravagant habits of the people who live here." "The largest cities may contain more than ten million human inhabitants." "And where there are people, there is food, lots of it." "A city this size produces around 10,000 tonnes of waste a day." "If the residents are not to drown in a morass of leftovers, it all needs to be cleaned up, continuously." "Good hygiene is so important in these crowded conditions that much time and money is spent trying to sanitise our cities." "But it isn't easy to wipe away the evidence of food, not completely anyway." "To an animal with an acute sense of smell, food stands out." "Everything else seems grey by comparison." "We may not notice the scraps left behind, but what's not taken away can become an opportunity for others." "Under the partial cover of darkness, a familiar face materialises." "Racoons have found our cities very much to their liking." "Their great climbing skills enable them to find shelter in roofs and chimney breasts during the day and also to move with ease in all parts of this complex environment - a fact recorded by security cameras every night of the year." "To find food, racoons must descend to the ground." "They're bold and intelligent animals and negotiate the dangers of the road as confidently as humans." "Indeed, city racoons are significantly less likely to be hit by a car than their country cousins, who get less experience of judging the speeds of vehicles." "In an attempt to thwart garbage raiders, rubbish collection continues around the clock." "But racoons are quick to take advantage of any opportunities." "If there's food around, they'll find it." "The skills that made racoons so successful in their original home also serve them well here, in the fast lane." "The inquisitiveness they showed when looking for food on the forest floor now leads them to rich pickings." "The manual dexterity that enabled them to capture crayfish in streams now leads them to take off the lids of dustbins... and winkle morsels from jars, boxes and tins." "Racoons are an American success story." "Their population has increased twenty times since the 1930s, and their range has expanded by 30%." "They're one of the most successful and widespread mammals on the continent." "The biggest opportunists of all have a slightly less subtle approach." "Bears can break into cars as easily as they can open clam shells." "It takes more effort, but the rewards can be huge." "In Britain, the streets belong to a different urban prowler - the red fox." "Unlike racoons, foxes are territorial, but they're also extremely adaptable." "In a single year, a fox can change from being totally rural to totally urban, so foxes are always on the move." "If I were to explore these city streets for just a few hours," "I'd almost certainly see more foxes than I would in a whole year of walking in the countryside." "Cities like this can support ten times as many foxes as a similar area in the country." "Foxes have one other thing going for them, at least here in Britain - their popularity." "Surveys regularly show that the red fox is among the nation's favourite mammals, a fact that foxes have been quick to exploit." "Many of us encourage our friendly neighbourhood foxes by putting out food, and the foxes are only too glad to take it." "In this city, some 60% of a fox's diet comes from free handouts, and the more food there is, the more foxes there are." "However, there is another kind of urban opportunist that is much more successful than the red fox." "But it's at the opposite end of the popularity scale." "We don't encourage it in any way, and yet it thrives on our leftovers." "If statistics are anything to go by, you are within five metres of one at all times." "There's probably one directly beneath me as I speak." "Warm water emptying from baths and washing machines and sluicing into the network of sewers beneath our homes creates a surprisingly stable and temperate environment." "It's an ideal habitat for one of the most widespread and adaptable mammals - the brown rat." "It's not just the steady temperature that the rats like." "There's a steady supply of food as well." "Scraps flushed down the sewers enable a rat to spend its entire life here, though, contrary to popular belief, there's not enough food to support swarms of rats." "The only thing they need worry about is a sudden rise of water level." "Sewer rats are particularly sensitised to this, often with good reason." "Her nest is in danger of flooding, but fortunately she knows a safer place to take her babies." "They're guided very largely by smell, and follow tried and tested routes that they know to be safe." "Moving six youngsters under such conditions seems a hard task, but rats are resilient creatures, a characteristic that makes them suited to living in these unnatural surroundings." "In spite of their numbers, we seldom see rats out and about." "But we all know they're there, eating our food and probably spreading disease, so we wage war on them with traps and poison." "What happens when rats are allowed to live unchecked in a human society?" "In this temple in northern India, rats are sacred." "Local people believe that after death they return to Earth as rats, so rats here are fed and protected and, indeed, worshipped." "This is not just a rat haven, it is a rat heaven, and the rats take full advantage of it." "In the wild, rats are nocturnal, but not here." "These rats don't shun the daylight like city rats." "Why should they?" "There's nothing to harm them here and plenty of food, and, as a result, they swarm in great numbers." "Colonies in the wild, which grow to be about 600-strong, normally then break down and divide, but here their population has stabilised at around 6,000." "The size of the world-wide population of rats is incalculable." "Their boundless opportunism means that today they inhabit every continent on Earth, including Antarctica." "Could there be a more successful mammal?" "Well, yes...us, the human species." "We are the ultimate demonstration of just how successful a mammal can be that is prepared to eat pretty well anything." "This is the Kumbh Mela, a spectacular Hindu festival in central India attended by millions of people." "It's the largest gathering of people for a common cause ever seen in the history of the world." "Over two weeks, this temporary city on the banks of the Ganges will shelter a staggering one hundred million people." "Since they're Hindus, most are strictly vegetarian, but across the world we seem to be able to thrive whatever the diet;" "whether it be one dominated by lentils and rice or by hamburgers." "We have learned how to create our own food resources, so our population is no longer limited by the quantity of food that occurs naturally." "That development enabled us first to dominate the Earth and eventually to overrun it." "An essential key to our success has been the one that we share with rats and racoons, bears and foxes - an adaptable nature and an ability to seize an opportunity when we see it." "You might say that it's not the meek that have inherited the Earth, but the opportunists."