"They are born to move... to join the chase... racing against the clock... to reach all-too-brief Edens." "And teaching their young that in a restless world... timing is everything." "Right now our planet is on the march... on the wing... on the run." "And these are the tales of its creatures... the most moving stories on Earth... the stories of the great migrations." "[zebra braying]" "It's spring in the Southern Hemisphere, and Africa's painted horses luxuriate in the waters of Botswana's paradise- the Okavango Delta." "Here, the yearly floods create the largest inland delta in the world." "And the siren song of water brings together one of the richest panoramas of wildlife on Earth." "Magnificent plains zebras must drink their fill now." "They are about to set off on one of the most curious migrations in the world out of this flooded paradise and into a brutal inferno." "With eyes on the horizon, they wait for the rains to fall to the south- watering their path into a dry purgatory that holds the key to their survival." "[thunder]" "Family by family, the stallions lead their mares out of Eden." "Their strange destination:" "a killing flat desert of dust and salt known as the Makgadikgadi Salt Pans." "Leaving Botswana's rich delta, they will travel beyond its watery fingers into the salt pans, a 150-mile slog into hell." "[braying]" "Almost immediately, the zebras enter the desiccated grasslands beyond the delta- where water grows scarce." "Dozens become hundreds... and then thousands as the Okavango family groups join up with others on the strange pilgrimage into the pans." "The herd presents a bewildering chaos of stripes to predators." "But for the zebras, these stripes mean everything." "Each animal has a unique pattern, as distinct and recognizable as faces are to us." "It's how this baby will find its mother from among the riot of patterns." "Two young lions stalk the herd." "They know that if they shadow the migration long enough, heat and distance will take their toll." "It's too hot to kill by day." "That will come later." "[zebra squealing]" "[snarling] [bellowing]" "The next morning, the herd seems to take solace in each other." "They have lost several members to the lions." "They step carefully in each other's tracks now, creating a tapestry of their migration." "The occasional rains here have left temporary waterholes to sustain them on their journey." "But these oases are shrinking, so they must now hurry- into the deadlands of the salt pans." "Like the zebras, virtually all migrating creatures" "live by a ticking clock." "For most, it is the seasons that hasten their journeys to worlds of plenty." "And in the far north, the migratory clock ticks down according to the whims of the ice." "Here, ice is haven and compass, port and transport, for the titans of the Arctic." "[groaning]" "Off the Alaskan coast, male walruses rest on floating bachelor pads." "But their platforms are shrinking, and close quarters cause tempers to flare." "They abandon their melting havens in an epic search for food and dry land." "The fate of a walrus lies in the vagaries of the ice- and the Arctic has become temperamental lately." "Not far from the males, females have also been contending with melting sanctuaries." "Born less than a day ago, a pup follows his mother into freezing water." "He now gets a swimming lesson as tender as any human child has received." "It looks like fun, but this is serious business." "The females and the young must soon begin their own migration in pursuit of ice- and the little ones must keep up." "The females curve northward through the Bering Strait, headed for the usually ice-filled waters off of Russia's Wrangel Island, while their male counterparts make for the shores of the Chukchi Sea." "Now the bulls are converging on their destination after weeks and hundreds of miles at sea." "They struggle ashore;, pink with their efforts." "Unlike the females, they summer on dry land." "Crowded, cranky and uncomfortable, they will at least be safe." "But for the females, luck- and ice-have run out." "Where once they would have found frozen seas, there is only open water." "Not built to swim long distances, and used to resting on floes, they will have to add a new and dangerous leg to their journey." "They turn south along the Russian coast... headed for an epic collision of migrations... and end up off the same beaches where the males have staked their claim." "There are few suitable haul-out spots." "They must now attempt landfall among the crush of males." "There's no turning back." "The mechanism of the Arctic's great clock-its ice- has wound down, stranding them here." "And the watchmaker, the sun, tilts higher in the sky each day." "The days of ice are far off... and young lives hang in the balance." "Everywhere in the Northern Hemisphere, spring is changing landscapes... and unleashing grand movements of creatures." "[coyote howls]" "The icons of the American West have always embodied movement, freedom, migration for animals and humans alike- proud... [elk bugling] ...unconstrained, always on the move." "Those days are slipping away- but one indomitable creature insists on maintaining its ancient journey" "the pronghorn." "Each year, a small band follows the longest migration in the Americas below the Arctic." "Only these determined 200 have managed to stick to the old routes." "Sometimes called the American antelope, this creature is no antelope at all." "In fact, it has no close living relative anywhere in the world." "Shy but gutsy, and by far the fastest land animal in the New World, the pronghorn can move at up to 60 miles per hour." "It will need its speed and grit to beat the seasonal clock." "From southern Wyoming, this herd will travel north more than 120 miles to the Tetons, a long way against longer odds to reach their calving grounds." "[machine chugging]" "Nothing in the pronghorn's evolution could prepare them for this gauntlet." "[truck approaching] [horn blows]" "[automobile whizzes by]" "[crow calling]" "[dog barking]" "The pronghorn must pass through human-made bottlenecks as narrow as a quarter mile." "And so they are now running two races- against the spreading human footprint... and against the march of the seasons." "Eventually they enter more promising terrain- a spate of red hills untouched by man." "Driven on by a memory sustained over thousands of generations, they know that better lies ahead." "But they are not home free." "Fences are formidable barriers and potential deathtraps." "[crow calling]" "But never underestimate this creature's unconquerable will to live." "As winter eases, snowmelt transforms the landscape." "Creeks can be hurdled." "But rivers such as the Gros Ventre require nerves of steel." "Rarely seen, this fording is perilous." "But the pronghorn are impelled to try it... no matter the odds." "Once crossed, they're home... in the glorious safety of Grand Teton National Park." "A place free from barbed wire and deadly highways." "The right kind of neighborhood for raising children." "Each a triumph for this hardy band of survivors." "Fleet of foot and strong of heart, who will trace prehistoric pathways to greener pastures... for as long as we will let them." "In Africa, the pastures are anything but green." "After two hot weeks of walking, the zebras have reached the inferno of the Makgadikgadi Salt Pans." "They hungrily nibble and lip at the mineral deposits of this ancient lake- feeding a life-or-death craving." "Now the mystery of their strange and brutal migration becomes clear:" "they've traded the heaven of a lush delta- for one of the largest salt-licks in the world." "The tall harsh grasses would seem to be an unpleasant mouthful- but these have absorbed precious minerals from the pans." "Energized by their new diet, they kick up their heels." "Now they can escape from this scorched earth- in search of remaining water." "It has been a long time between rains, but a few waterholes remain." "Milky with the mud and salt of this place, the water will nonetheless have to slake the thirst of hundreds." "Cranky ostriches tower over the zebras, clearly unhappy about the four-legged monopoly at the waterhole." "Stallions bark orders at their harems, trying to maintain control." "Bachelor males harass young females... fraying equine nerves." "Females are riveted by the fights." "The outcomes determine their own destinies." "The future fathers of their foals." "They go for slender legs with their teeth." "And...they kick." "[zebra braying]" "A victorious male rounds up his harem." "After weeks in the pans, the waterholes are drying up." "Time to head back in the direction of the Okavango Delta." "So they will retrace the steps of their strange journey." "A journey that will take a terrible toll." "A mother has died." "Her foal bewildered and refusing to move." "His young father brought up short by conflicting ties." "His son-or his hard-won harem." "Still nursing, the colt appears doomed." "The stallion seems to consider his options... while his harem presses on." "The foal turns back to his mother... and tries to rouse her- a choice that should prove fatal." "His father seems unwilling to give up on him- and a stunning act of parental sacrifice is about to unfold." "Where night falls on the earth, it brings many great land migrations to a halt." "But wherever the sun goes down on the world's oceans, a massive microscopic migration begins- one that feeds and regenerates our entire planet- and it happens every single day." "Each night, in all our oceans, trillions of tiny dynamos rise to the surface to eat- a luminous blizzard of microorganisms who make up the largest migration on Earth." "They are plankton- the minuscule larvae of shrimp, crabs, lobsters and other creatures, spinning like frenetic stars and galaxies in deep space." "These minute, gorgeous creatures anchor the food chains that feed our blue planet." "In the waters of the Caribbean, just beyond Belize's Great Barrier Reef, another microscopic feast is about to erupt." "An irresistible lure to the largest fish on Earth." "From a whirl of thousands of cubera snapper, a dark shape emerges" "a true sea monster." "At up to 40 feet long and 20 tons, the whale shark has timed its migration perfectly to be here at this instant." "The shark has no interest in the snapper themselves- but something more precious- their unborn young." "A far-off beacon announces that it's time... a full moon." "And it begins." "A vortex of fish, a volcano of procreation... erupting as females release eggs and males release sperm." "These spasms of milky lava are why the whale sharks have come, to vacuum in massive quantities of eggs and milt." "And there is yet another feast for the sharks." "The dog snapper have also heard the call of the moon... streaming to the surface and exploding with their genetic hopes." "Then, they surge back to the depths, their procreative duty done." "When they have had their fill, the massive, graceful sharks will move on... in search of the next brief gift from our bountiful seas." "[bird squawking]" "Like the seas, rainforests demand exquisite timing from creatures chasing pulses of plenty." "And a spectacular feast is about to explode here in the emerald heart of Borneo." "Draped across the equator of Southeast Asia," "Borneo is the third largest island in the world, and home to 1 50,000 square miles of rainforest... and today, one riotously blooming tree." "And so rush hour begins in the green highways of the canopy." "Primates predominate in the race through the treetops, dazzling acrobatics on display." "Even the insect-hunting Draco lizard seems to want to get in on the act- covering nearly 200 feet in a single fantastic leap of faith." "The cause of all this et enkelt ruckus :" "a single tree about to explode with fruit- the strangler fig." "The only one for miles around, it blossoms just once every two years- and only for a few brief weeks." "Its figs- fragrant, sweet and nutritious- are here for the picking- for those who get here soon enough." "Among the first to arrive is the slowest-the orangutan." "This mother and baby have the tree to themselves for a rare calm moment... thanks to mom's mental map." "She knows each tree and its season, and gets here before the rush." "But their leisurely monopoly of the tree is about to come to an end." "Spritely red leaf monkeys arrive and hurl themselves at the feast." "Long-tailed macaques vault into fruited branches." "And the true Olympian of the forest makes a splashy arrival:" "the gray gibbon." "This single tree can produce up to 40,000 figs- becoming a hub of mini-migrations for five miles in any direction." "With so much to eat, the creatures of the canopy can relax... and attend to...other matters." "But the bounty cannot last." "Soon the remaining fruit will spoil on the branch." "So eating becomes serious business." "The gibbon becomes covetous of the remaining figs." "The sight of a red leaf monkey enjoying his breakfast irritates her." "[monkey shrieking]" "Frayed nerves are a sign that the days of plenty are running out." "This stupendous tree has worked its fleeting magic- called together a vast congregation- and fed it extravagantly." "Now the creatures in its crown scramble to get a head start in the next race." "Once again, they will fly..." "Ieap... swing... and glide... until they find the next short but sweet feast in the Borneo forest." "At the top of the world, along the coast of Russia's Chukchi Sea, the exhausted female walruses rest." "Mothers bob in the surf, sound asleep, some clutching babies to them." "Sooner or later, though, they'll need to clamber ashore... on a beach already packed with bad-tempered males." "Tentatively, they haul out." "Desperate latecomers have no choice but to climb." "With 20,000 walruses on the beach, bodies stretch far up the slopes." "They've reached a critical mass." "Creatures weighing up to two tons clamber over a heaving sea of flesh and tusks." "Before finding a spot, a walrus can travel half a mile without ever touching the ground." "Bewildered youngsters flounder amidst the chaos of stray tusks and raw tonnage in the mounting crisis." "[walruses barking]" "Inevitably, the crush proves deadly." "But now, a sign of hope." "Snow signals the end of the short Arctic summer." "With winter bearing down in the far north, the sea should begin freezing again." "And the call of the ice frees them from the deadly beach." "So they pour into the sea, taking up their migration once again... following the ice, for as long as they can." "Out of the blistering salt pans of Botswana, the zebras have emerged into the grasslands- but not unscathed." "The foal tries in vain to rouse his dead mother." "His handsome father is about to do something startling." "While his harem pushes on, he lets them go- the center of his life, his reason for being." "Instead, he gambles on his son- but will the son trust him?" "A heartrending tug of war begins." "While the motherless son watches, the father marches up and down in front of him." "Again and again, the youngster returns to his dead mother." "But whenever he looks up, his father resumes his pacing." "It's a desperate parade that will go on for hours." "Is he just torn between his son and his departing mares... or is there a more astounding possibility?" "The stallion may be trying to imprint his stripes over those of the mother's in the foal's brain." "But time is short." "[hissing]" "Finally, the scavengers decide the issue." "The father herds his son away from the awful spectacle." "[zebra braying]" "The male calls for his harem, but they have put many hours and miles between themselves and the lost pair." "[braying]" "They mingle with straggling strangers at the end of the line... curious, but aloof." "No one has ever seen a female adopt an orphan- but perhaps his father knows better." "[braying]" "For better or worse, father and son have thrown in their lot together." "By sunset, they have caught up with the body of the herd... their future uncertain, but their bond unbreakable." "And so the unlikely pair soldiers on..." "like great nomads the world over... unflagging and undaunted." "Moving in masses... surviving as one." "Their path is aflame with sun-fired dust." "But ahead they can smell the richly watered landscape of the Okavango Delta... and the pungent aroma of hope."