行星地球第一集：两极之间 From Pole To Pole

[00:37.51]A hundred years ago [00:39.03] [00:39.15]there were one and a half billion people on Earth. [00:43.19] [00:44.98]Now, over six billion crowd our fragile planet. [00:49.83] [00:51.23]But even so, there are still places barely touched by humanity. [00:56.91] [01:01.83]This series will take to the last wildernesses [01:05.75] [01:05.87]and show you the planet and its wildlife [01:08.79] [01:08.91]as you have never seen them before. [01:11.58] [02:00.39]Imagine our world without sun. [02:04.11] [02:05.26]Male Emperor Penguins are facing the nearest that exists on planet Earth - [02:10.71] [02:10.87]winter in Antarctica. [02:13.27] [02:15.03]It's continuously dark [02:16.67] [02:16.79]and temperatures drop to minus seventy degrees centigrade. [02:21.74] [02:31.83]The penguins stay when all other creatures have fled [02:35.07] [02:35.19]because each guards a treasure: [02:37.63] [02:37.75]A single egg rested on the top of its feet [02:40.79] [02:40.91]and kept warm beneath the downy bulge of its stomach. [02:44.71] [02:49.66]There is no food and no water for them, [02:52.23] [02:52.35]and they will not see the sun again for four months. [02:55.78] [02:55.91]Surely no greater ordeal is faced by any animal. [03:00.66] [03:10.43]As the sun departs from the Antarctic [03:13.39] [03:13.51]it lightens the skies in the far north. [03:16.99] [03:25.43]It's March [03:26.71] [03:26.83]and light returns to the high Arctic, [03:29.83] [03:29.95]sweeping away four months of darkness. [03:33.43] [03:45.91]A polar bear stirs. [03:48.46] [03:48.59]She has been in her den the whole winter. [03:51.87] [03:51.94]Her emergence marks the beginning of spring. [03:56.23] [03:58.63]After months of confinement underground [04:01.15] [04:01.27]she toboggans down the slope. [04:03.23] [04:03.35]Perhaps to clean her fur, [04:05.39] [04:05.58]perhaps for sheer joy. [04:08.35] [04:22.67]Her cubs gaze out of their bright new world [04:26.15] [04:26.27]for the very first time. [04:28.38] [04:30.71]The female calls them, [04:32.42] [04:32.55]but this steep slope is not the easiest place to take your first steps. [04:38.35] [04:51.06]But they are hungry [04:52.58] [04:52.70]and eager to reach their mother, [04:54.27] [04:54.39]who's delayed feeding them on this special day. [04:57.79] [04:57.94]Now she lures them with the promise of milk, [05:00.34] [05:00.46]the only food the cubs have known since they were born [05:03.62] [05:03.75]deaf and blind beneath the snow some two months ago. [05:08.42] [05:24.19]Their mother has not eaten for five months [05:27.55] [05:27.67]and has lost half her body weight. [05:30.39] [05:30.59]Now she converts the last of her fat reserves into milk for her cubs. [05:36.47] [05:54.51]The spring sun brings warmth [05:57.11] [05:57.23]but also a problem for the mother. [06:00.03] [06:00.47]It starts to melt the sea ice. [06:03.27] [06:03.38]That is where she hunts for the seal she needs to feed her cubs. [06:07.39] [06:07.51]And she must get there before the ice breaks up. [06:11.07] [06:14.74]For now though it's still minus thirty degrees [06:17.95] [06:18.07]and the cubs must have the shelter of the den. [06:21.47] [06:34.87]It's six days since the bears emerged [06:37.91] [06:38.03]and spring is advancing rapidly. [06:40.63] [06:40.75]But even now blizzards can strike without warning. [06:44.39] [06:47.27]Being so small, [06:48.51] [06:48.63]the cubs are easily chilled and they will be more comfortable resting in the den. [06:53.27] [06:53.39]But their mother must keep them out and active. [06:56.47] [06:57.91]She's becoming weak from hunger [06:59.55] [06:59.66]and there's no food on these nursery slopes. [07:02.62] [07:09.03]The sea ice still holds firm, [07:11.19] [07:11.46]but it won't last much longer. [07:13.74] [07:17.02]Day 10, [07:17.87] [07:18.10]and the mother has led her cubs a mile from the den. [07:21.67] [07:21.79]It's time to put them to the test. [07:24.54] [07:26.99]They've grown enormously in confidence, [07:29.59] [07:29.71]but they don't have their mother's sense of urgency. [07:33.47] [07:48.51]At last it seems that they're ready for their journey [07:51.87] [07:51.99]and they're only just in time, [07:53.63] [07:53.78]for a few miles from the coast the ice is already splitting. [07:58.26] [08:04.35]Now the mother can start hunting for the seals they must have, [08:07.91] [08:08.03]but she's leading her cubs into a dangerous new world. [08:12.51] [08:13.15]Nearly half of all cubs die in their first year out on the ice. [08:18.31] [08:28.11]Summer brings 24 hours of sunlight [08:31.51] [08:31.62]and the thawing shifting landscape. [08:34.83] [08:37.42]Further south the winter snows have almost cleared from the Arctic tundra. [08:42.63] [08:50.55]Northern Canada's wild frontier. [08:53.66] [08:53.78]Here nature stages one of her greatest dramas - [08:58.31] [09:05.51]Every year three million caribou migrate across the Arctic tundra. [09:11.83] [09:24.19]The immensity of the herd can only be properly appreciated from the air. [09:30.35] [09:37.18]Some herds travel over 2,000 miles a year in search of fresh pastures. [09:42.95] [09:43.06]This is the longest overland migration made by any animal. [09:48.91] [09:59.71]They're constantly on the move. [10:01.99] [10:02.11]Newborn calves have to be up and running the day they are born. [10:05.98] [10:26.19]But the vast herds do not travel alone. [10:30.79] [10:33.26]Wolves. [10:34.59] [10:36.95]Packs of them, eight to ten strong, shadow the migration. [10:41.59] [10:43.47]And they are hungry. [10:44.79] [10:50.26]It's the newly born calves that they are after. [10:54.27] [11:01.11]Running directly at the herd is a ploy to generate panic. [11:05.63] [11:15.83]The herd breaks up [11:17.22] [11:17.35]and now it's easier to target an individual. [11:21.02] [11:31.27]In the chaos a calf is separated from its mother. [11:35.22] [11:41.59]The calf is young, [11:42.83] [11:42.94]but it can outrun the wolf if only it manages to keep its footing. [11:47.51] [11:59.79]At this stage the odds are even - [12:02.51] [12:02.63]either the caribou will make a mistake [12:04.71] [12:04.83]or after a mile the wolf will give up. [12:07.82] [12:55.15]Midsummer on the tundra [12:57.14] [12:57.27]and the sun does not set. [12:59.86] [13:02.70]At these latitudes the sun's rays are glancing [13:06.43] [13:06.55]and not enough of their energy reaches the ground [13:09.14] [13:09.31]to enable trees to grow. [13:11.74] [13:14.11]You'll need to travel 500 miles south from here [13:17.15] [13:17.30]before that is possible. [13:19.06] [13:25.11]These stunted shrubs mark the tree line - [13:28.59] [13:28.71]the beginning of the boreal forest - [13:31.87] [13:32.07]the taiga. [13:33.19] [13:42.27]The needle-shaped leaves of the conifers are virtually inedible [13:46.15] [13:46.27]so this forest supports very little animal life. [13:49.99] [13:56.39]It's a silent place [13:57.90] [13:58.03]where the snow is unmarked by footprints. [14:01.70] [14:10.59]In the Arctic winter [14:12.30] [14:12.43]snow forms a continuous blanket across the land. [14:16.59] [14:16.83]But as spring creeps up from the south [14:19.51] [14:19.63]the taiga is unveiled. [14:22.51] [14:27.71]This vast forest circling the globe [14:30.71] [14:30.82]contains a third of all the trees on Earth [14:34.19] [14:34.31]and produces so much oxygen [14:36.31] [14:36.43]it changes the composition of the atmosphere. [14:40.07] [14:42.59]As we travel south [14:44.19] [14:44.31]so the sun's influence grows stronger [14:47.30] [14:47.42]and at 50 degrees of latitude a radical transformation begins. [14:53.35] [15:02.83]Summers here are long enough for broadleaf trees to replace conifers. [15:09.19] [15:09.39]Broadleaves are much easier to eat and digest [15:13.03] [15:13.14]so now animals can collect their share of the energy [15:16.22] [15:16.35]that has come from the sun. [15:18.23] [15:19.70]It's summer [15:20.63] [15:20.75]and these forests are bustling with life. [15:24.18] [15:49.51]But the good times will not last. [15:52.54] [15:54.35]Broad leaves must be shed in winter for their damage by frost. [15:58.67] [15:58.79]As they disappear, [16:00.18] [16:00.31]so the land becomes barren with little for animals to eat. [16:05.06] [16:13.03]The inhabitants must migrate, [16:15.39] [16:15.51]hibernate, [16:16.74] [16:16.91]or face months of near starvation. [16:19.99] [16:37.79]The Amur leopard - [16:39.62] [16:39.66]the rarest cat in the world. [16:42.38] [16:45.34]Here, in the deciduous forests of eastern Russia [16:48.35] [16:48.47]the winter makes hunting very difficult. [16:51.22] [16:51.27]Pray animals are scarce, [16:52.95] [16:53.06]and there's no concealing vegetation. [16:55.87] [16:58.83]The cub is a year old and still dependent on its mother. [17:02.66] [17:10.83]Deer are frequent casualties of the harsh winter [17:14.31] [17:14.43]and these leopards are not above scavenging from a corpse. [17:18.35] [17:18.87]African leopards could never survive here, [17:22.23] [17:22.35]but the Russian cats have thick fur to shield them from the cold. [17:27.27] [17:32.90]There are only forty Amur leopards left in the wild [17:36.55] [17:36.67]and that number is falling. [17:38.63] [17:40.23]Like so many creatures, [17:41.62] [17:41.75]the cats have been pushed to the very edge of extinction [17:44.59] [17:44.71]by hunting and the destruction of their habitat. [17:48.38] [17:50.27]The Amur leopard symbolizes the fragility of our natural heritage. [17:55.75] [17:56.34]The future of an entire species hangs on survival [18:00.38] [18:00.51]of a tiny number of mothers like this one. [18:04.35] [18:09.71]All animals, rare or common, [18:11.99] [18:12.11]ultimately depend for their energy on the sun. [18:15.95] [18:23.50]In Japan the arrival of the cherry blossom [18:26.10] [18:26.22]announces the beginning of spring. [18:29.11] [18:49.71]The sun's energy brings color to the landscape. [18:53.87] [19:03.42]The earth, as it makes its annual journey around the sun, [19:06.90] [19:07.02]spins on a tilted axis. [19:09.54] [19:09.67]And it's this tilt that creates the seasons. [19:13.58] [19:38.10]The advance of the seasons brings constant change. [19:42.39] [19:43.39]As the sun's influence diminishes in the north, [19:46.18] [19:46.30]so the deciduous forests of America begin to shut down [19:50.71] [19:50.83]losing their leaves in preparation for the dark cold months ahead. [19:55.90] [20:09.71]One season hands over to another. [20:12.51] [20:12.63]Some organisms thrive on decay, [20:15.42] [20:15.55]but most must make special preparations for winter [20:19.02] [20:19.15]and a life with little sun. [20:21.51] [20:36.11]Whole populations of animals [20:38.15] [20:38.27]are now forced to travel great distances in pursuit of food and warmth. [20:44.27] [20:49.39]300,000 Baikal teal gather to escape from the Siberian winter [20:55.34] [20:55.46]by migrating south to Korea - [20:58.91] [21:01.43]the world's entire population in a single flock. [21:05.79] [21:09.79]But there are parts of the world that have no seasons. [21:14.19] [21:17.38]In the tropics the sun's rays strike the earth head on [21:21.39] [21:21.51]and their strength is more or less constant all year round. [21:25.91] [21:28.18]That is why the jungle grows so vigorously [21:30.90] [21:31.02]and supports so much life. [21:33.51] [21:35.11]This forest covers only 3 percent of the planet's surface, [21:38.83] [21:38.95]but it contains more than 50 percent of all its plants and animals. [21:44.03] [21:47.47]The canopy is particularly rich. [21:50.51] [21:50.83]There are monkeys, birds [21:52.62] [21:52.75]and millions of species of insects, [21:54.99] [21:55.10]exactly how many we have no idea. [21:57.99] [22:00.34]The character of the forest changes as we descend, [22:03.62] [22:03.74]becoming ever darker and damper, [22:06.19] [22:06.31]favoring different kinds of animals and plants. [22:09.94] [22:15.59]Less than 2 percent of the sunlight reaches the floor, [22:18.87] [22:18.99]but even here there is extraordinary variety. [22:22.63] [22:31.31]In the great island of New Guinea [22:33.43] [22:33.55]there are 42 different species of birds of paradise, [22:36.90] [22:37.03]each more bizarre than the last. [22:39.30] [23:05.46]This forest is so rich [23:07.19] [23:07.31]that nourishing food can be gathered very quickly. [23:10.50] [23:10.67]That leaves the male six-plumed bird of paradise [23:13.54] [23:13.66]with time to concentrate on other matters [23:16.15] [23:16.26]like tidying up his display area. [23:19.47] [23:28.70]Everything must be spick and span. [23:31.75] [23:39.55]All is ready. [23:41.11] [24:01.42]Very impressive, [24:02.74] [24:02.99]but no one is watching. [24:05.02] [24:07.03]The superb bird of paradise calls to attract a female. [24:11.51] [24:13.83]And he has more luck. [24:16.23] [24:16.99]But what does he have to do to really impress her? [24:21.15] [24:46.07]She retires to consider her verdict. [24:49.03] [24:55.42]It's hard not to feel deflated [24:57.67] [24:57.79]when even your best isn't good enough. [25:00.59] [25:20.50]The sun influences life in the oceans just as it does on land. [25:26.03] [26:11.19]Its richest parts are those where waves and currents [26:14.74] [26:14.87]bring fertilizing nutrients to surface waters [26:17.95] [26:18.07]that are bathed in sunlight. [26:19.99] [26:20.23]The seas off the Cape in South Africa have this magic recipe [26:24.51] [26:24.63]and are hugely productive. [26:26.94] [26:30.63]Summer is the time of plenty [26:32.62] [26:32.74]and it's now that the seals start to breed. [26:36.31] [27:00.03]The strike of a great white shark lasts a mere second. [27:04.58] [27:04.70]Slowing it down forty times reveals the technique [27:08.43] [27:08.55]and immense strength of this massive predator. [27:12.07] [27:48.79]If surprise fails, [27:50.79] [27:50.91]there will be a chase. [27:52.95] [28:02.79]The shark is faster on a straight course [28:05.87] [28:05.98]but it can't turn as sharply as the seal, [28:09.11] [28:11.71]its agility versus power. [28:14.03] [29:07.39]Once the seals have finished breeding [29:09.70] [29:09.83]the giant sharks will move on. [29:12.10] [29:14.59]It's now becoming clear [29:16.07] [29:16.19]that great whites migrate thousands of miles across the oceans [29:19.99] [29:20.11]to harvest seasonal abundances in different seas. [29:24.51] [29:50.35]The sun, beating down on tropical waters, [29:53.66] [29:53.79]powers the weather systems of the globe. [29:56.50] [29:56.79]Moisture evaporates from the warming ocean [29:59.51] [29:59.63]and rises to create great storms. [30:02.79] [30:22.98]The winds generated out at sea [30:25.38] [30:25.50]sweep inland across the continents. [30:28.78] [30:40.22]As they travel across the Sahara [30:42.27] [30:42.39]they create the biggest of all sand storms [30:45.67] [30:45.78]blowing sand halfway round the world [30:47.95] [30:48.07]to fertilize the Amazon jungle. [30:51.11] [30:55.87]Winds blowing across the Indian Ocean [30:58.98] [30:59.15]collect moisture and sweep northwards towards the Himalayas. [31:03.67] [31:04.66]As the air rises, so it cools. [31:07.87] [31:12.18]The water it carries [31:13.59] [31:13.71]condenses into clouds [31:15.75] [31:15.95]and then falls as the life giving rains of the monsoon. [31:20.35] [31:25.59]So air currents powered by the sun [31:28.78] [31:28.91]carry wet air to the middle of continents. [31:32.47] [31:51.11]Without water [31:52.43] [31:52.59]there can be no life, [31:54.18] [31:54.30]but its distribution over the land is far from even. [31:58.71] [32:05.19]Deserts cover one third of the land's surface [32:08.99] [32:09.23]and they're growing bigger every year. [32:11.91] [32:22.07]This is the Kalahari Desert in Southern Africa. [32:26.07] [32:26.67]It's the dry season [32:28.43] [32:28.54]and thousands of elephants have started to travel [32:31.31] [32:31.43]in desperate search for water. [32:33.99] [32:43.87]All across Southern Africa animals are journeying for the same reason. [32:49.35] [32:52.31]Buffalo join the great trek. [32:54.67] [32:54.87]Nowhere else on Earth are so many animals on the move [32:58.19] [32:58.27]with the same urgent purpose. [33:00.99] [33:04.98]They're all heading for the swamps of the Okavango, [33:09.02] [33:09.11]a vast inland delta. [33:11.59] [33:12.87]At the moment it is dry, [33:14.99] [33:15.39]but water is coming. [33:17.42] [33:19.47]The travelers are hampered by dangerous dust storms. [33:24.30] [33:27.66]Females and calves can easily get separated from the main herd. [33:32.11] [33:47.95]For this pair sanctuary lies in the patch of woodland a few miles ahead. [33:52.66] [33:52.83]They can't rest until they reach it. [33:55.35] [34:10.98]The main has already got there safely. [34:14.46] [34:19.43]Finally, the stragglers emerge from the dust. [34:23.47] [34:27.83]The exhausted calf is still blinded by sand. [34:32.43] [34:34.83]Its mother does everything possible to help it. [34:38.39] [34:50.95]The storm is now subsiding, [34:53.55] [34:53.91]but not all the elephants have been so lucky. [34:56.90] [34:57.47]One youngster has got lost. [35:00.15] [35:01.82]Thirsty and exhausted, [35:03.78] [35:03.87]it follows the tracks of its mother, [35:06.35] [35:06.70]but sadly in the wrong direction. [35:10.23] [35:33.47]At the peak of the dry season in the Kalahari [35:36.26] [35:36.43]water arrives in the Okavango. [35:39.31] [35:39.39]It fell as rain a thousand miles away in the highlands of Angola [35:43.31] [35:43.38]and has taken nearly five months to reach here. [35:46.83] [35:52.91]The water drives out insects from the parched ground, [35:57.15] [35:57.27]which are snapped up by plovers. [35:59.55] [36:02.99]Catfish, traveling with the flood, [36:05.03] [36:05.15]collect any drowning creatures the birds have missed. [36:08.83] [36:19.26]It's a seasonal feast for animals of all kinds. [36:23.59] [36:34.67]Birds are the first to arrive in any numbers - [36:37.99] [36:38.11]wattled cranes, [36:39.91] [36:41.03]then black storks. [36:43.55] [36:45.39]Behind the birds come buffalo. [36:48.43] [36:48.55]After weeks of marching their trek is coming to an end. [36:52.79] [37:10.99]As the water sweeps into the Okavango [37:13.58] [37:13.71]a vast area of the Kalahari is transformed into a fertile paradise. [37:20.11] [37:23.06]Nowhere on our planet is the life giving power of water so clearly demonstrated. [37:29.59] [37:33.47]The Okavango becomes criss-crossed with trails [37:36.58] [37:36.70]as animals move into its heart. [37:39.03] [37:39.51]The new arrivals open up paths like arteries [37:42.26] [37:42.35]along which water flows, [37:44.34] [37:44.43]extending the reach of the flood. [37:46.71] [38:06.23]This is an Africa rarely seen - [38:09.30] [38:09.98]a lush water world. [38:12.26] [38:29.43]Some creatures are completely at home here. [38:32.19] [38:32.31]These are lechwe - [38:34.18] [38:34.30]antelope with hooves that splay widely, [38:36.99] [38:37.11]enabling them to move its speed through the water. [38:40.43] [38:41.23]For others the change is far less welcome. [38:44.71] [38:50.78]Baboons are somewhat apprehensive bathers. [38:54.63] [39:25.71]The water brings a season of plenty for all animals. [39:31.55] [39:44.91]Hunting dogs. [39:46.67] [40:05.91]These are now among the rarest of Africa's mammals, [40:09.55] [40:09.67]but then nonetheless the continent's most efficient predators. [40:13.71] [40:15.79]Their secret is teamwork. [40:18.58] [40:22.23]Impala are their favorite prey. [40:25.11] [40:26.19]They start to hunt [40:27.39] [40:27.51]and the pack splits up. [40:29.55] [40:30.43]An aerial viewpoint gives a new insight into their strategy. [40:34.55] [40:35.55]As the dogs approach their prey [40:37.43] [40:37.54]they peel off to take up separate positions around their target. [40:41.87] [40:53.43]They seem to form a cordon around the impala. [40:57.03] [41:05.58]Moving in total silence [41:07.71] [41:07.83]they take up their positions. [41:09.87] [41:14.19]Those ears can detect the slightest rustle. [41:17.67] [41:38.51]The hunt is on. [41:40.31] [41:44.07]Three dogs close in on one impala. [41:47.63] [41:56.10]Missed. [41:57.03] [42:01.27]The lead dog drives the impala towards the hidden flankers. [42:05.67] [42:15.39]Anticipating their line [42:16.79] [42:16.87]the leader cuts the corner [42:18.55] [42:18.63]and joins a flanker for the final assault. [42:21.59] [42:23.79]It's all or nothing. [42:25.27] [42:25.34]One on one. [42:26.74] [42:30.90]The dog has stamina, [42:32.30] [42:32.42]the impala has speed. [42:34.75] [42:48.02]Leaping into the lake is an act of desperation - [42:51.18] [42:51.30]impala can barely swim. [42:53.31] [42:56.99]The dogs know their prey must come out or drown - [43:00.19] [43:00.27]now it's a waiting game. [43:02.86] [43:10.63]The rest of the pack are calling. [43:12.98] [43:14.30]They've made a kill in the forest [43:16.31] [43:16.43]and this is an invitation to join in the meal. [43:19.95] [43:23.55]The impala is in luck. [43:25.86] [43:33.55]A pack this size kills once a day and everything is shared. [43:38.59] [43:47.67]And this impala is reprieved. [43:50.79] [43:58.99]The elephants are nearing the end of their long journey. [44:02.99] [44:04.87]After weeks of marching they're desperately tired. [44:09.35] [44:16.70]The matriarch can smell water [44:18.75] [44:18.83]and encourages the herd to make one last effort. [44:22.35] [44:32.47]The youngsters are exhausted [44:33.99] [44:34.07]but their mothers have made this journey before [44:36.39] [44:36.47]and they know that they're close to water. [44:38.91] [44:55.63]After many hundreds of miles they've arrived. [45:00.03] [46:07.86]The lives of these elephants are dominated by the annual rhythm of wet and dry, [46:13.71] [46:13.79]a seasonal cycle created by the sun. [46:17.46] [46:47.07]At the southern end of the earth, [46:48.86] [46:48.95]after four months of total darkness, [46:51.50] [46:51.58]the sun once more rises over Antarctica. [46:55.74] [47:09.19]Now at last the Emperor penguins abandon their huddle. [47:13.74] [47:13.83]The males are still carrying the precious eggs [47:16.71] [47:16.78]that they've cherished throughout the Antarctic winter. [47:20.43] [47:27.91]With the returning sun the eggs hatch. [47:31.83] [47:32.99]Other birds have not even arrived. [47:35.78] [47:35.87]But the Emperors by enduring the long black winter [47:39.70] [47:39.79]have given their chicks a head start. [47:43.39] [47:52.19]These youngsters are now ready and eager to make the most of the brief Antarctic summer. [47:59.59]

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