"They are born to move." "To pursue the feast." "Defying the desert with ancient wisdom." "Gracefully chasing the nurturing sun." "Pursuing titanic prey in turquoise seas." "Marvels of motion... in search of a meal." "Right now our planet is on the march... on the wing... on the run." "And these are the tales of its relentless hungers... in the most moving stories on Earth." "The stories of the great migrations." "On the scorched edge of the Sahara Desert, mammoth silhouettes shimmer like mirages in the heat." "Rare desert elephants- the last of their kind... cling to life in a world that can barely sustain them- dedicated to sustaining each other." "This is Africa's infamous Sahel- arid scrublands marking the southern fringe of the Sahara." "The only way to survive here is to move- in an endless quest for water and food- both in desperately short supply." "So these great creatures take on the longest elephant migration on Earth- in a vast, 300-mile circle around the heart of landlocked Mali in West Africa." "To lead them in their desert wanderings, each family looks to the matriarch- the oldest female." "She has spent decades memorizing the migration route, knowing where and when water and food is most likely to be found." "They can smell it now- water, just over the horizon- a desperately needed way station in their migration." "[cattle lowing]" "But they are not the only nomads making their way here." "The local Tuareg and Fulani herders know the oasis lies just ahead." "It is Lake Banzena- a glittering blessing in a world of thirst." "Of the many birds drawn here, red-billed quelea come by the hundreds of thousands- perhaps the most numerous bird species on Earth." "In a haze of quelea, the elephants arrive" "and finally slake their thirsts." "The cattle drink contentedly." "But the elephants take their enjoyment to a higher level." "[elephants trumpeting and rumbling]" "Now family after family emerges from the Sahel into the oasis, matriarchs at the helm." "A new arrival has made her appearance, just a couple of weeks old, delighted to gambol in the mud under the watchful eye of her mother and aunts." "She is so precious to them." "After nearly two years in the womb, the biological investment she represents is enormous." "Patient mothers and aunts crowd gently around her." "She will need their tender wisdom during the long trek ahead... because Lake Banzena will not last long in this year's drought." "And the elephants desperately await a signal to resume their scorching migration towards their next sanctuary:." "A rare uninhabited opening through a sheer wall separating them from where the rains should soon fall." "It's called La Porte Des Elephants- The Elephant's Door." "The intelligent elephants have passed down the knowledge of how to get here and when for countless generations." "Other creatures reflexively follow the seasons- compelled to keep moving despite terrifying risks- simply to keep themselves fed." "Some follow their senses- to brief explosions of food." "And some seem to be all hunger, all instinct, all the time- somehow knowing where their prey are gathering- oceans away." "In the cobalt gloom of the Pacific, a solitary wanderer makes its way east:" "the great white shark." "She is one of the world's greatest migrants, covering thousands of miles of open ocean a year." "Hunger is driving her- and dozens of other sharks- toward a stupendous feast" "The shark's enormous appetite propels her through an annual migration that stretches from Hawaii to the island of Guadalupe." "This volcanic thrust of rock is unwelcoming and unforgiving." "But its waters are another story altogether" "abundant with marine life." "The strange mola mola... dolphins... rare beaked whales... and countless Guadalupe fur seals." "Nature's perfect huntress arrives:" "the giant female great white- more than 1 5 feet long and weighing nearly a ton." "The shark seems uninterested in the seals." "And the agile seals seem to know it." "Apparently she has something much bigger and slower on her menu... the northern elephant seal." "After many months at sea, and a migratory wandering of up to 13,000 miles, scores of these giants have hauled out here to pup and mate... some already bearing the scars of the great white's hunger." "[snoring and rumbling]" "But not all of the elephant seals have arrived yet." "Young females, making their first homecoming to Guadalupe to breed, are hauling out late." "[bellowing]" "They are innocent of the ways of the sharks... and the sharks are wise in the ways of the seals." "It is a gruesome collision of nomadic giants... a feast for one, death for another." "Once sated, the great whites will move on- heading for distant Hawaii- and their next moveable feast." "While the sharks follow their long migrations in the Pacific, another highway of hunger conducts the winged masses of the Americas from feast to feast." "It is the Great Mississippi Flyway." "Spring comes slowly in the Upper Mississippi River Valley- but this great artery is always pumping with the lifeblood of avian migrations." "The white pelican, like tens of millions of North America's migrating waterbirds and shorebirds, follows this ancient route." "[ducks quacking]" "Some will stay here to greet the summer, to mate and breed, and feed on the Mississippi's abundant offerings." "For some, it is a refueling depot on the way further north." "But for the predators riding their tailwinds... the migrants themselves are the feast." "The swooping silhouette of a bald eagle sends ripples of terror along the waterways." "[ducks quacking]" "But he is here for easier pickings." "The melt thrusts countless fish out of their graves." "It's a bizarre seasonal exhumation, and raptors keenly follow its northward progress." "White pelicans, on their way further north, await better flying conditions." "The unmistakable mallard duck conducts his gentle courtship in a driving rain" "and defends his patch of river with comic ferocity." "Many, like the mallards, may stay here to raise their young." "But for others...spring whispers urgently to head north." "Raptors like this adolescent bald eagle work their way along the river bluffs, riding the thermals and updrafts." "Sometimes they blunder into someone else's airspace." "These peregrine nestlings would seem exposed and vulnerable." "But their mother is a fearless defender of her nest site... which the bald eagle is about to learn." "The peregrine falcon, whose name translates to "wanderer,"" "has one of the longest migrations of any bird in North America." "Some come from as far south as Peru;" "others may reach the Arctic." "From this perfect vantage on the flyway, falcon parents raise their brood on the many smaller migrants," "like songbirds, now passing through." "Gaping beaks demand up to a dozen corpses a day from their harried parents." "[squawking]" "The constant comings and goings on the river mean one thing- the menu for the great raptors is about to change again." "Half a world away, far from the hustle and bustle of the mighty Mississippi," "Iie the islands of Palau, which plays host to a remarkable migratory feast made possible by an even more remarkable partnership." "1 2,000 years ago, melting glaciers fed rising seas... and the ocean began to seep into a speck of an island in the Pacific, creating a lake like no other." "The few creatures that trickled in here with the sea evolved in quiet isolation." "And the most triumphant survivor gave the lake its name..." "Jellyfish Lake." "Golden jellyfish by the millions thrive here, but have a bargain to keep." "A bargain that drives two remarkable daily migrations of mutual hunger." "The jellyfish survive, thanks to millions of generous guests that actually live inside their bodies- tiny, dynamic algae that turn sunlight into sugar." "The sugar feeds the jellies, and the jellies dedicate their lives to tending the algae." "And so they follow the sun." "At dawn, it begins." "The sun's flare beckons, and the jellyfish stream eastward." "Flapping bells propel them towards the light that will feed this symbiosis." "Five million golden creatures, colored by the algae they harbor, glide across the lake's surface." "On the far edge of their journey lies darkness... the shadows." "Blind but acutely sensitive to light, they sense the lake's edge and the mangroves that harbor predators." "Shifting tides bring some into the dark underworld." "Cardinal fish await the strays- alongside the innocuous looking anemone, waving deadly tentacles." "Little blennies nip at the jellies' arms, rendering them rudderless... to drift into the voracious grasp of the anemones." "Once trapped, the jelly is attacked from all sides." "It is a lucky jellyfish that escapes from the merciless mangrove shallows alive." "And those that do beat a hasty retreat... back to light and life... in pursuit of the now westward-leaning sun, to feed its internal fellow travelers, its algae." "But as the sun falls, their Faustian bargain will call upon the jellyfish to make a more dangerous migration... into a terrible and toxic abyss." "All migrating animals make dangerous bargains in their search for food." "They risk becoming food themselves." "They surmount formidable barriers... chasing rains that may never fall, blossoms that may not bloom, grasses that may not grow." "When nature doesn't hold up her end of the bargain... they are stalked by starvation." "And on the cracking oasis of Lake Banzena in Mali, the nurturing sun is turning deadly." "[elephant rumbling]" "In just a few weeks, the elephants have watched the lake disappear before their eyes." "The water, churned and polluted by elephants and livestock, turns to muck." "But they can't leave here until the rains begin to fall to the south, allowing them to take up the next leg of their journey." "They're stripping the vegetation at the lake's edge at an alarming rate." "The elephants hurry back to the waterhole, their month-old baby in tow." "Today, there is yet another addition to the herd- a calf, just hours old, unsteady and painfully thin." "All of the youngsters will struggle on the forced march to come... but the newborn is in real trouble." "And this is a place without pity." "Noon finds the baby lying in the savage equatorial sun... his mother trying to urge him to his feet while his worried grandmother looks on." "No amount of encouragement can rouse the inner stricken baby." "His mother is just a teenager- in elephant terms, very young to have a baby- perhaps too young." "She will not willingly leave him." "But now an interloper appears on the scene." "A young bull, apparently mistaking the smells of her recent birth for estrus, drives her into the bush." "Grandmother lingers for a while, keeping a hopeless vigil." "But soon she, too, will be forced to return to the business of eating in preparation for the journey ahead." "For now, though, they are virtually trapped here." "Only one thing will make their break for freedom, something other than a suicide run." "[thunder]" "And finally it comes:" "the distant promise of rain over the horizon." "[rumbling]" "But there is one sad ritual to attend to before they leave- the mysterious and moving elephants' funeral." "They return to the dead newborn, its sad remains mummified in little more than a week in the intense dry heat." "With infinite tenderness, they smell, touch and hold the bones." "It is said that only human hearts can be broken." "But the elephants' final goodbyes seem to speak volumes of hurt." "The little girl, though, seems healthy and strong." "She'll need to be, because the race of her young life is about to begin." "An apocalyptic sight unfurls on the horizon:" "and day is about to become suffocating night." "[birds calling]" "Summer sets in along the upper Mississippi." "Hot humid days lie heavily over new swamps, where the river has slopped over its banks." "But these waterways provide cover for three exuberant Canadian goslings." "These precocious babies are born knowing how to swim and to feed on the river's rich supply of plants and insects." "And July is about to touch off a fantastic blizzard of food." "In the muck at the bottom of the river, something is stirring." "These are mayfly larvae, and they're about to erupt, all at once... by the millions." "Clutching at low-hanging vegetation, they burst as adult flies from their larval shells... and they're on a mission." "They have just 24 hours in which to fly, mate, give birth... and die." "This dense whirling dervish of sex and death is so thick it shows up on weather radar." "Now the feasting begins." "Songbirds have come by the millions for the banquet... some having bitten off more than they can chew." "Birds are not the only beneficiaries." "Leaping, flying leopard frogs hurl themselves at the yearly feast" "Ieaping with their tongues." "But the vast majority of these bugs survive, to shed their spawn back into the Mississippi... then die, bringing the feast back to the water." "Now, changing colors announce the arrival of fall- reversing the flow on the winged highway from northbound to south." "The season brings the bald eagle a mighty and macabre feast." "The American coot, many coming back from Canada, headed as far south as Central America." "They huddle together in tight "rafts" for safety in numbers." "But safety for the flock and safety for the individual are not the same thing." "When a coot is snatched by fierce talons, its ordeal has only begun." "A single coot might be caught, stolen and dropped into the water six or seven times before it is consumed." "For the eagles, this seems like some sort of ghastly game." "[eagle cries]" "The gray days of fall urge the summer residents and those passing through to move on." "The little geese are now completely transformed, and utterly dedicated to the proposition that they should be airborne." "So bonded are they to one another that they don't yet understand the need for a wing's breadth of elbow room." "Soon enough, they will break free of their Mississippi nursery and join the honking wedges headed south... criers of the winter to come." "It's time for final farewells to this part of the river- and the skies of the Mississippi Flyway fill again with the enthralling sight of feathered migrants on the wing." "Day is turning to night in the South Pacific, and it's time for the jellyfish to carry out the more dangerous part of their mortal bargain." "The algae that live inside them, that feed them, now need to be fed a toxic brew." "One that lies 45 feet down." "And so they sink, through the layers of the lake's waters." "They descend in search of the bacterial layer, which decomposes the lake's dead organisms, full of nutrients the algae desperately need." "But for the jellies, it's a wasteland:" "poisonous pink hydrogen sulfide swirls... there is no oxygen here." "Those who remain down here too long will suffocate... victims of their life-or-death bargain." "But those who remain just long enough to soak their algae in rich nutrients return to the surface... and wait... ready to rush towards the dawn, to begin their sun-worshipping migrations once again... feeding and fed in perfect synchronicity." "In central Mali, it's as if the world were ending." "A 60-mile-an-hour tsunami of sand and dust engulfs the elephant family." "The storm galvanizes the matriarch and the herd." "They will make a break south, towards the elusive smell of rain." "The human nomads follow in their footsteps, knowing the elephants can read the weather far better than they." "[elephant rumbling]" "As the dust settles, and the days drag on, matriarchs join forces, families merging into a huge elephant army." "There are expanding human settlements along the route, and the wary elephants find their passage being narrowed year by year." "Youngsters struggle to keep up." "But adults, too, are felled by the killing heat." "At the head of the march, the matriarch of matriarchs senses that they are nearing their goal:" "that rare human-free passage through the sheer cliffs that stand between them and their next oasis." "At dawn, as the sun kisses the edge of the elephant's door, they finally arrive, energized by the seductive smells beyond." "[thunder]" "Now nothing stands between them and the rains falling a day's march ahead- no more cliffs or humans." "There, they will be able to rest and eat- before they resume their ancient journey." "Testament to the wisdom of their mothers, the last of the great desert elephants survive... to soldier on against the odds... moving together... surviving as one."