1 00:00:01,266 --> 00:00:05,542 {\an8}♪♪ 2 00:00:05,566 --> 00:00:09,376 [ Wind whistling ] 3 00:00:09,400 --> 00:00:14,876 {\an1}SCOTT: The Arctic has always been the toughest test, 4 00:00:14,900 --> 00:00:18,342 no more so than in the far corner of Alaska 5 00:00:18,366 --> 00:00:22,276 {\an1}called the Arctic National Wildlife Refuge. 6 00:00:22,300 --> 00:00:25,500 Thousands of caribou face the cold... 7 00:00:27,266 --> 00:00:30,042 the terrain... 8 00:00:30,066 --> 00:00:35,109 {\an1}and formidable predators to reach one special place 9 00:00:35,133 --> 00:00:37,176 {\an1}at just the right time... 10 00:00:37,200 --> 00:00:41,533 {\an1}a vast, beautiful plain on the edge of the Arctic Ocean. 11 00:00:43,966 --> 00:00:46,200 {\an1}Here, they give birth. 12 00:00:49,166 --> 00:00:52,609 {\an1}This is the story of the last great land migration 13 00:00:52,633 --> 00:00:54,266 in North America. 14 00:00:56,466 --> 00:01:01,742 {\an1}And of how every Arctic creature is now on a daunting journey 15 00:01:01,766 --> 00:01:05,909 from a timeless past into a vastly different future. 16 00:01:05,933 --> 00:01:13,933 {\an8}♪♪ 17 00:01:47,200 --> 00:01:53,209 {\an8}♪♪ 18 00:01:53,233 --> 00:01:55,209 SCOTT: On the top of the world, 19 00:01:55,233 --> 00:01:57,876 {\an1}it is still the ice age. 20 00:01:57,900 --> 00:02:05,900 {\an8}♪♪ 21 00:02:10,166 --> 00:02:13,276 {\an1}It's northern Alaska in winter. 22 00:02:13,300 --> 00:02:15,709 The temperature drops to 50 below. 23 00:02:15,733 --> 00:02:23,733 {\an8}♪♪ 24 00:02:27,200 --> 00:02:30,742 {\an7}Frozen rivers curl north from the Brooks Range 25 00:02:30,766 --> 00:02:33,976 and down to a plain stretching to the Beaufort Sea 26 00:02:34,000 --> 00:02:37,109 and the Arctic Ocean, now locked in ice. 27 00:02:37,133 --> 00:02:40,709 [ Wind whistling ] 28 00:02:40,733 --> 00:02:43,342 {\an1}This vast stretch of white mountains, 29 00:02:43,366 --> 00:02:45,476 {\an1}tundra, and icy rivers, 30 00:02:45,500 --> 00:02:48,942 {\an1}forms one of the world's most important wildernesses... 31 00:02:48,966 --> 00:02:52,609 The Arctic National Wildlife Refuge. 32 00:02:52,633 --> 00:02:56,033 {\an1}It's a home for courageous creatures from another time. 33 00:03:00,300 --> 00:03:03,209 {\an1}This wildlife community will face a year 34 00:03:03,233 --> 00:03:04,966 {\an1}of difficult decisions. 35 00:03:08,200 --> 00:03:12,742 {\an1}Hundreds of miles southeast, bravest of all perhaps, 36 00:03:12,766 --> 00:03:16,242 {\an1}is a pregnant caribou. 37 00:03:16,266 --> 00:03:19,209 She's part of the Porcupine caribou herd 38 00:03:19,233 --> 00:03:22,442 {\an1}and will undertake the longest annual land migration 39 00:03:22,466 --> 00:03:24,509 on the planet. 40 00:03:24,533 --> 00:03:28,176 {\an1}In her lifetime, she's likely to walk the same distance 41 00:03:28,200 --> 00:03:32,276 as a complete circuit of the globe. 42 00:03:32,300 --> 00:03:35,376 {\an1}It's December, and the caribou are waiting, 43 00:03:35,400 --> 00:03:38,109 {\an1}eating lichen in the twilight. 44 00:03:38,133 --> 00:03:42,476 {\an1}The journey ahead needs precise timing. 45 00:03:42,500 --> 00:03:44,676 {\an1}She'll march through forests, 46 00:03:44,700 --> 00:03:46,942 {\an1}over mountains, across rivers, 47 00:03:46,966 --> 00:03:48,609 to the coastal plain. 48 00:03:48,633 --> 00:03:52,476 {\an8}It's a round trip of almost a thousand miles. 49 00:03:52,500 --> 00:03:56,309 {\an8}♪♪ 50 00:03:56,333 --> 00:03:58,942 {\an8}Some 160,000 caribou 51 00:03:58,966 --> 00:04:00,909 {\an8}will walk from their wintering grounds 52 00:04:00,933 --> 00:04:03,709 {\an8}in the Yukon and Northwest Territories 53 00:04:03,733 --> 00:04:07,233 {\an7}to their calving grounds in the Wildlife Refuge. 54 00:04:09,233 --> 00:04:11,542 {\an8}♪♪ 55 00:04:11,566 --> 00:04:14,109 The Brooks Range stands in their way, 56 00:04:14,133 --> 00:04:17,742 {\an1}running parallel to the coast. 57 00:04:17,766 --> 00:04:21,409 {\an1}The sun sets for the last time until the New Year. 58 00:04:21,433 --> 00:04:29,433 {\an8}♪♪ 59 00:04:32,400 --> 00:04:35,976 {\an1}The only sunlight is reflected by a wintry moon. 60 00:04:36,000 --> 00:04:44,000 {\an8}♪♪ 61 00:04:44,500 --> 00:04:46,409 {\an1}Hundreds of miles above, 62 00:04:46,433 --> 00:04:50,076 solar radiation fires up the ionosphere, 63 00:04:50,100 --> 00:04:51,709 {\an1}and the ghostly aurora. 64 00:04:51,733 --> 00:04:59,733 {\an8}♪♪ 65 00:05:07,400 --> 00:05:09,676 This is a world of huge planetary 66 00:05:09,700 --> 00:05:13,142 {\an1}forces in constant flux. 67 00:05:13,166 --> 00:05:17,742 {\an1}This is nature at its most spectacular and extreme. 68 00:05:17,766 --> 00:05:24,742 {\an8}♪♪ 69 00:05:24,766 --> 00:05:29,276 [ Wolf howls ] 70 00:05:29,300 --> 00:05:33,476 {\an1}A dawn twilight returns in January. 71 00:05:33,500 --> 00:05:41,500 {\an8}♪♪ 72 00:05:41,800 --> 00:05:44,642 {\an1}Blizzards blast the tundra. 73 00:05:44,666 --> 00:05:49,076 {\an1}Most animals have left or are hibernating under the deep snow, 74 00:05:49,100 --> 00:05:50,842 but musk ox remain. 75 00:05:50,866 --> 00:05:53,042 [ Growling ] 76 00:05:53,066 --> 00:05:56,742 [ Wind whistling ] 77 00:05:56,766 --> 00:06:01,042 {\an1}They are loyal to a home range and won't leave. 78 00:06:01,066 --> 00:06:03,276 {\an1}They rarely visit the valley. 79 00:06:03,300 --> 00:06:04,909 The snow is too deep, 80 00:06:04,933 --> 00:06:08,176 {\an1}and they can't dig out the frozen grass. 81 00:06:08,200 --> 00:06:11,033 {\an1}Even up here, it's hard work. 82 00:06:16,566 --> 00:06:20,176 Winters seem to be more erratic recently, 83 00:06:20,200 --> 00:06:22,576 on average more than eight degrees warmer 84 00:06:22,600 --> 00:06:26,342 than 50 years ago, which sounds better, 85 00:06:26,366 --> 00:06:30,266 {\an1}but now there's freezing rain on top of heavier snowfall. 86 00:06:33,433 --> 00:06:35,942 {\an1}The caribou are becoming restless. 87 00:06:35,966 --> 00:06:41,442 {\an8}♪♪ 88 00:06:41,466 --> 00:06:45,409 {\an1}Her belly is beginning to swell with her unborn calf. 89 00:06:45,433 --> 00:06:50,842 {\an8}♪♪ 90 00:06:50,866 --> 00:06:55,942 {\an1}She's searching for reindeer lichen, her winter food. 91 00:06:55,966 --> 00:06:59,142 She's a reindeer as much as a caribou. 92 00:06:59,166 --> 00:07:01,276 {\an1}They are the same species. 93 00:07:01,300 --> 00:07:06,676 {\an8}♪♪ 94 00:07:06,700 --> 00:07:10,876 She digs through snow like the musk ox. 95 00:07:10,900 --> 00:07:12,542 {\an1}For a prospective mother, 96 00:07:12,566 --> 00:07:16,376 finding enough food is her principal focus. 97 00:07:16,400 --> 00:07:18,576 {\an1}But it's not her only worry. 98 00:07:18,600 --> 00:07:26,600 {\an8}♪♪ 99 00:07:29,833 --> 00:07:32,142 It's a lone wolf. 100 00:07:32,166 --> 00:07:40,166 {\an8}♪♪ 101 00:07:44,733 --> 00:07:48,276 {\an1}The caribou's instinct is to stay on the move. 102 00:07:48,300 --> 00:07:51,076 {\an1}Somewhere has to be better than this. 103 00:07:51,100 --> 00:07:56,776 {\an8}♪♪ 104 00:07:56,800 --> 00:08:00,109 But migration is not blind instinct. 105 00:08:00,133 --> 00:08:04,076 {\an1}It's a series of collective decisions based on subtle clues 106 00:08:04,100 --> 00:08:07,876 to weather patterns and journey times. 107 00:08:07,900 --> 00:08:10,066 {\an1}Every year is different. 108 00:08:13,033 --> 00:08:15,709 The wolf has choices to make, too. 109 00:08:15,733 --> 00:08:19,276 {\an1}He can follow the caribou, but they move fast, 110 00:08:19,300 --> 00:08:21,500 {\an1}and the journey is too far. 111 00:08:27,133 --> 00:08:30,009 {\an1}The first birth of spring. 112 00:08:30,033 --> 00:08:31,542 It's not a caribou, 113 00:08:31,566 --> 00:08:35,842 {\an1}but a newborn musk ox, a 30-pound baby, 114 00:08:35,866 --> 00:08:39,809 delivered straight onto the snow. 115 00:08:39,833 --> 00:08:42,009 {\an1}The family surrounds her, 116 00:08:42,033 --> 00:08:45,466 {\an1}a protection from dangers outside their circle. 117 00:08:57,600 --> 00:09:02,642 But within hours, the calf wants out. 118 00:09:02,666 --> 00:09:05,366 {\an1}There's a beautiful new world to explore. 119 00:09:13,466 --> 00:09:16,309 {\an1}Every calf is precious. 120 00:09:16,333 --> 00:09:19,209 Musk ox were hunted to extinction in Alaska 121 00:09:19,233 --> 00:09:21,009 in the 1860s, 122 00:09:21,033 --> 00:09:24,842 but were brought back in the 1930s. 123 00:09:24,866 --> 00:09:28,166 {\an1}There are now a few thousand here in Alaska. 124 00:09:32,900 --> 00:09:36,533 {\an1}A little river gully is a new adventure for the calf. 125 00:09:42,000 --> 00:09:46,809 {\an1}Once in, getting back out is harder. 126 00:09:46,833 --> 00:09:54,833 {\an8}♪♪ 127 00:09:58,700 --> 00:10:00,509 {\an1}The mother won't follow. 128 00:10:00,533 --> 00:10:02,876 She doesn't know how deep the snow is 129 00:10:02,900 --> 00:10:04,766 {\an1}and could easily get stuck. 130 00:10:08,700 --> 00:10:11,542 {\an8}She tracks her calf from the bank. 131 00:10:11,566 --> 00:10:19,566 {\an8}♪♪ 132 00:10:20,466 --> 00:10:22,809 The calf discovers... 133 00:10:22,833 --> 00:10:24,609 ice. 134 00:10:24,633 --> 00:10:28,242 {\an8}♪♪ 135 00:10:28,266 --> 00:10:30,709 [ Calf lowing ] 136 00:10:30,733 --> 00:10:38,733 {\an8}♪♪ 137 00:10:44,366 --> 00:10:47,733 {\an1}There's a physical urgency to find your feet here... 138 00:10:50,500 --> 00:10:53,942 {\an1}...but perhaps a greater mental urgency for the calf 139 00:10:53,966 --> 00:10:56,242 {\an1}to figure out her world. 140 00:10:56,266 --> 00:11:00,276 {\an8}♪♪ 141 00:11:00,300 --> 00:11:03,142 {\an1}The patient mother waits... 142 00:11:03,166 --> 00:11:05,709 {\an1}and her calf finds a way out. 143 00:11:05,733 --> 00:11:13,733 {\an8}♪♪ 144 00:11:26,233 --> 00:11:28,342 She's got maybe another two years 145 00:11:28,366 --> 00:11:30,742 {\an1}looking after this youngster. 146 00:11:30,766 --> 00:11:34,209 The herd of about 15 will protect the calves 147 00:11:34,233 --> 00:11:38,966 {\an1}and search for food around their large home range until summer. 148 00:11:49,300 --> 00:11:53,542 The caribou have left the winter woodland far behind, 149 00:11:53,566 --> 00:11:55,809 {\an1}and are heading north. 150 00:11:55,833 --> 00:12:03,833 {\an8}♪♪ 151 00:12:05,766 --> 00:12:08,609 By April, the snow is starting to melt, 152 00:12:08,633 --> 00:12:12,742 {\an1}and many rivers run earlier than a decade ago. 153 00:12:12,766 --> 00:12:17,976 {\an1}Spring is moving north faster, and the caribou need to keep up. 154 00:12:18,000 --> 00:12:25,876 {\an8}♪♪ 155 00:12:25,900 --> 00:12:29,242 {\an1}The herd heads on for about a hundred miles, 156 00:12:29,266 --> 00:12:30,909 then will turn west 157 00:12:30,933 --> 00:12:33,942 {\an1}towards the Arctic National Wildlife Refuge. 158 00:12:33,966 --> 00:12:39,142 {\an8}♪♪ 159 00:12:39,166 --> 00:12:43,142 {\an1}It's the end of April. They are over halfway. 160 00:12:43,166 --> 00:12:44,709 {\an1}The mothers will all give birth 161 00:12:44,733 --> 00:12:47,576 within days of the third of June. 162 00:12:47,600 --> 00:12:49,233 Six weeks to go. 163 00:12:53,800 --> 00:12:57,642 [ Birds chirping ] 164 00:12:57,666 --> 00:13:01,509 Golden eagles nest along the route. 165 00:13:01,533 --> 00:13:03,042 {\an1}They came up from the south 166 00:13:03,066 --> 00:13:05,776 {\an1}and established territories in March, 167 00:13:05,800 --> 00:13:09,600 feeding on hares, ptarmigan, or marmots. 168 00:13:11,800 --> 00:13:17,542 {\an1}The eagle pair returns to the same spectacular nest each year. 169 00:13:17,566 --> 00:13:22,476 {\an1}They are loyal to a site decided over a decade ago. 170 00:13:22,500 --> 00:13:25,309 {\an1}But the calendar has changed a lot since then. 171 00:13:25,333 --> 00:13:27,833 {\an1}[ Chirping continues ] 172 00:13:37,133 --> 00:13:40,376 {\an1}By early May, the chicks are near fledging, 173 00:13:40,400 --> 00:13:43,633 and the caribou herd has already passed. 174 00:13:51,966 --> 00:13:54,700 {\an1}A ground squirrel is breakfast. 175 00:14:00,733 --> 00:14:02,733 [ Insects buzzing ] 176 00:14:07,333 --> 00:14:09,642 {\an1}It will take a new generation of eagles 177 00:14:09,666 --> 00:14:13,833 {\an1}to make the huge adjustment to the changes unfolding here. 178 00:14:17,300 --> 00:14:22,476 {\an1}A lone wolf has stuck with the herd for many miles. 179 00:14:22,500 --> 00:14:30,500 {\an8}♪♪ 180 00:14:40,033 --> 00:14:44,042 {\an1}Caribou from a broad area either side of the Canadian border 181 00:14:44,066 --> 00:14:46,709 are converging on the same route. 182 00:14:46,733 --> 00:14:50,342 {\an1}They'll navigate around the eastern end of the Brooks Range, 183 00:14:50,366 --> 00:14:53,342 about 40 miles from the Arctic shore. 184 00:14:53,366 --> 00:15:01,366 {\an8}♪♪ 185 00:15:06,566 --> 00:15:09,876 In a few places, the route has bottlenecks 186 00:15:09,900 --> 00:15:12,242 {\an1}around rivers and lakes. 187 00:15:12,266 --> 00:15:20,266 {\an8}♪♪ 188 00:15:27,300 --> 00:15:31,442 {\an1}This migration of Arctic caribou is compared to wildebeest 189 00:15:31,466 --> 00:15:35,476 {\an1}on the African savanna, and so the coastal plain 190 00:15:35,500 --> 00:15:39,576 is sometimes called America's Serengeti. 191 00:15:39,600 --> 00:15:47,600 {\an8}♪♪ 192 00:15:51,733 --> 00:15:53,909 As the herd funnels through the foothills 193 00:15:53,933 --> 00:15:55,609 of the Brooks Range, 194 00:15:55,633 --> 00:15:58,800 {\an1}the wolf briefly gains an advantage. 195 00:16:08,600 --> 00:16:13,009 {\an1}The weaker calves from last year are struggling to keep up. 196 00:16:13,033 --> 00:16:15,442 {\an1}There's been little time to stop and eat. 197 00:16:15,466 --> 00:16:22,509 {\an8}♪♪ 198 00:16:22,533 --> 00:16:24,909 {\an1}As long as the herd stays watchful 199 00:16:24,933 --> 00:16:28,076 {\an1}and maintains a distance, they're safe. 200 00:16:28,100 --> 00:16:36,100 {\an8}♪♪ 201 00:16:37,033 --> 00:16:39,909 Caribou are faster. 202 00:16:39,933 --> 00:16:42,142 {\an1}The wolf is a tactician, 203 00:16:42,166 --> 00:16:45,542 but tactics are hard if you work alone. 204 00:16:45,566 --> 00:16:53,566 {\an8}♪♪ 205 00:17:07,000 --> 00:17:11,009 {\an1}Here is an unparalleled amount of food on the hoof, 206 00:17:11,033 --> 00:17:15,309 {\an1}but to this lone wolf, it might as well not be here at all. 207 00:17:15,333 --> 00:17:23,333 {\an8}♪♪ 208 00:17:28,633 --> 00:17:33,576 {\an1}By May, spring has reached the Arctic National Wildlife Refuge. 209 00:17:33,600 --> 00:17:35,442 [ Buzzing ] 210 00:17:35,466 --> 00:17:39,800 {\an1}Life here has slept under snow for eight months. 211 00:17:41,266 --> 00:17:44,542 [ Chirps ] 212 00:17:44,566 --> 00:17:48,276 Plovers and redpolls arrive to nest, 213 00:17:48,300 --> 00:17:51,033 part of a massive aerial migration. 214 00:17:55,166 --> 00:17:59,276 {\an1}Millions of snow geese leave California or Texas 215 00:17:59,300 --> 00:18:03,276 and are on their way to the Arctic Islands of Canada. 216 00:18:03,300 --> 00:18:06,209 They'll stop off here on their way back. 217 00:18:06,233 --> 00:18:14,233 {\an8}♪♪ 218 00:18:18,233 --> 00:18:21,609 {\an1}Sandpipers are part of the worldwide event. 219 00:18:21,633 --> 00:18:27,542 {\an8}♪♪ 220 00:18:27,566 --> 00:18:31,342 {\an1}Golden plovers set off from Argentina. 221 00:18:31,366 --> 00:18:35,809 {\an1}Terns, loons, and songbirds come from Antarctica 222 00:18:35,833 --> 00:18:38,876 {\an1}or Africa or East Asia. 223 00:18:38,900 --> 00:18:41,909 Hundreds of species cross the planet 224 00:18:41,933 --> 00:18:44,442 on their way to the Arctic north. 225 00:18:44,466 --> 00:18:52,466 {\an8}♪♪ 226 00:18:58,166 --> 00:19:03,609 {\an1}A world of birds is heading to the summer paradise of Alaska. 227 00:19:03,633 --> 00:19:11,633 {\an8}♪♪ 228 00:19:12,866 --> 00:19:15,876 [ Chirping ] 229 00:19:15,900 --> 00:19:21,242 {\an1}The golden plover couple have arranged a nest on the ground, 230 00:19:21,266 --> 00:19:24,933 laid their eggs, and are raising their chicks. 231 00:19:38,233 --> 00:19:41,976 {\an1}The parents provide some protection against Arctic foxes 232 00:19:42,000 --> 00:19:44,076 or predatory birds, 233 00:19:44,100 --> 00:19:47,800 {\an1}but it's mainly just warmth under a camouflaged wing. 234 00:19:58,533 --> 00:20:02,476 {\an1}Once thawed out, the chicks have to get back to finding food 235 00:20:02,500 --> 00:20:04,133 for themselves. 236 00:20:17,266 --> 00:20:20,242 {\an1}The mother leaves after a couple of weeks, 237 00:20:20,266 --> 00:20:23,742 {\an1}and the father follows a week or so later. 238 00:20:23,766 --> 00:20:25,976 {\an1}But the chicks stay longer 239 00:20:26,000 --> 00:20:29,633 {\an1}and have to find their own way back to South America. 240 00:20:32,600 --> 00:20:35,142 In the meantime, the chicks catch insects 241 00:20:35,166 --> 00:20:37,142 {\an1}for as long as they can, 242 00:20:37,166 --> 00:20:40,066 {\an1}then come running back to warm up again. 243 00:20:45,066 --> 00:20:48,542 {\an1}Their mother knows it's not just the cold that will get them. 244 00:20:48,566 --> 00:20:49,933 [ Chirps ] 245 00:21:00,833 --> 00:21:05,833 {\an1}Arctic foxes live in tunnels in the layer above the permafrost. 246 00:21:11,100 --> 00:21:12,842 The parents returned a few months ago 247 00:21:12,866 --> 00:21:17,376 {\an1}from their winter wanderings in snowy white coats 248 00:21:17,400 --> 00:21:20,533 to give birth and turn brown for summer. 249 00:21:27,066 --> 00:21:30,509 {\an8}♪♪ 250 00:21:30,533 --> 00:21:34,342 {\an1}The cubs were born here in early May. 251 00:21:34,366 --> 00:21:36,909 {\an1}Now, a few weeks later, 252 00:21:36,933 --> 00:21:39,742 they enjoy the remarkably warm days. 253 00:21:39,766 --> 00:21:47,766 {\an8}♪♪ 254 00:22:02,466 --> 00:22:05,476 {\an1}They need to grow up fast. 255 00:22:05,500 --> 00:22:07,976 The cubs are already eating meat 256 00:22:08,000 --> 00:22:11,009 {\an1}and seem constantly hungry. 257 00:22:11,033 --> 00:22:13,642 Ground squirrels and nesting birds are here 258 00:22:13,666 --> 00:22:16,466 in large numbers in May and June. 259 00:22:18,566 --> 00:22:21,242 {\an1}One delivery is not enough for them all. 260 00:22:21,266 --> 00:22:26,609 {\an8}♪♪ 261 00:22:26,633 --> 00:22:29,342 {\an1}The others don't notice the mother's return 262 00:22:29,366 --> 00:22:31,376 {\an1}until it's almost too late. 263 00:22:31,400 --> 00:22:39,400 {\an8}♪♪ 264 00:22:52,566 --> 00:22:54,076 Oh, well. 265 00:22:54,100 --> 00:22:56,076 {\an1}Dad will be back soon with more. 266 00:22:56,100 --> 00:23:00,800 {\an8}♪♪ 267 00:23:03,000 --> 00:23:05,942 {\an1}It's a constant meal service during days 268 00:23:05,966 --> 00:23:08,066 {\an1}that never quite seem to end. 269 00:23:12,600 --> 00:23:15,909 Nesting on the ground is dangerous, 270 00:23:15,933 --> 00:23:21,776 {\an1}but there is one bird that would fight off any fox... the jaeger. 271 00:23:21,800 --> 00:23:24,500 {\an1}Jaeger means hunter in German. 272 00:23:27,500 --> 00:23:30,642 {\an1}The caribou are beginning to arrive. 273 00:23:30,666 --> 00:23:36,076 {\an1}They are tired, hungry, many are about to give birth, 274 00:23:36,100 --> 00:23:39,533 {\an1}and they could so easily tread on a bird's nest. 275 00:23:43,800 --> 00:23:47,176 {\an1}The jaegers are not going to let that happen. 276 00:23:47,200 --> 00:23:50,009 {\an1}They start with some gentle warnings, 277 00:23:50,033 --> 00:23:52,342 {\an1}but the caribou ignore them. 278 00:23:52,366 --> 00:23:56,509 {\an8}♪♪ 279 00:23:56,533 --> 00:23:59,542 {\an1}Yet the jaegers are fearless. 280 00:23:59,566 --> 00:24:07,566 {\an8}♪♪ 281 00:24:18,133 --> 00:24:21,176 {\an1}The caribou mother has come hundreds of miles, 282 00:24:21,200 --> 00:24:23,176 {\an1}faced raging torrents, 283 00:24:23,200 --> 00:24:26,842 been jammed by lakes, escaped wolves, 284 00:24:26,866 --> 00:24:29,409 and now there's a determined parent bird 285 00:24:29,433 --> 00:24:31,509 that doesn't want her here at all. 286 00:24:31,533 --> 00:24:39,533 {\an8}♪♪ 287 00:24:40,666 --> 00:24:44,642 {\an1}The caribou respond to the swooping bird ballet 288 00:24:44,666 --> 00:24:47,142 with strange dance moves of their own. 289 00:24:47,166 --> 00:24:55,166 {\an8}♪♪ 290 00:25:22,266 --> 00:25:24,376 {\an1}As more of the herd arrives, 291 00:25:24,400 --> 00:25:28,166 {\an1}the jaegers battle tirelessly to keep their eggs safe. 292 00:25:30,233 --> 00:25:34,700 {\an1}For the birds, and for all life here, there's little rest. 293 00:25:37,100 --> 00:25:39,242 {\an1}Even the sun keeps going, 294 00:25:39,266 --> 00:25:43,176 {\an1}skimming above the horizon for most of June. 295 00:25:43,200 --> 00:25:51,200 {\an8}♪♪ 296 00:25:53,200 --> 00:25:56,276 {\an1}This midnight sun warms the caribou 297 00:25:56,300 --> 00:25:59,709 {\an1}as they all finally reach their destination. 298 00:25:59,733 --> 00:26:07,733 {\an8}♪♪ 299 00:26:08,766 --> 00:26:11,176 {\an1}These are their calving grounds, 300 00:26:11,200 --> 00:26:15,009 {\an1}in the heart of the Arctic National Wildlife Refuge. 301 00:26:15,033 --> 00:26:20,309 {\an8}♪♪ 302 00:26:20,333 --> 00:26:24,709 {\an1}She must arrive precisely, so that she's in the right place 303 00:26:24,733 --> 00:26:27,442 {\an1}when, a week to 10 days after the snow melts, 304 00:26:27,466 --> 00:26:31,233 {\an1}the sedges and grasses are at their most nutritious. 305 00:26:33,666 --> 00:26:36,642 Somewhere is a mother giving birth... 306 00:26:36,666 --> 00:26:44,042 {\an1}one new calf among 160,000, anonymous to all but each other. 307 00:26:44,066 --> 00:26:48,276 {\an1}Almost all the mothers give birth within a few days. 308 00:26:48,300 --> 00:26:56,300 {\an8}♪♪ 309 00:26:58,866 --> 00:27:02,742 {\an1}The calf doubles in size in two weeks. 310 00:27:02,766 --> 00:27:06,709 {\an1}The first green flush of sedges is briefly high in protein 311 00:27:06,733 --> 00:27:10,009 and sugars and coincides within a few days 312 00:27:10,033 --> 00:27:13,409 of when the calf needs most milk. 313 00:27:13,433 --> 00:27:17,009 {\an1}A week or so later, the grass will become coarser, 314 00:27:17,033 --> 00:27:20,076 {\an1}bitter, and indigestible. 315 00:27:20,100 --> 00:27:27,509 {\an8}♪♪ 316 00:27:27,533 --> 00:27:29,676 {\an1}The caribou slowly spread out, 317 00:27:29,700 --> 00:27:34,242 {\an1}surfing a wave of melting snow and growing grass. 318 00:27:34,266 --> 00:27:42,266 {\an8}♪♪ 319 00:27:43,333 --> 00:27:45,576 {\an1}The successful flood of energy 320 00:27:45,600 --> 00:27:48,842 transforms the character of the caribou. 321 00:27:48,866 --> 00:27:54,176 {\an8}♪♪ 322 00:27:54,200 --> 00:27:57,342 The first people here feel part of it. 323 00:27:57,366 --> 00:28:01,876 {\an1}Humans and caribou were created as one, they believe, 324 00:28:01,900 --> 00:28:06,909 {\an1}and each still contains a piece of each other's heart. 325 00:28:06,933 --> 00:28:10,042 To the Gwich'in, this is the sacred place 326 00:28:10,066 --> 00:28:12,542 where life begins. 327 00:28:12,566 --> 00:28:20,566 {\an8}♪♪ 328 00:28:29,833 --> 00:28:35,809 {\an1}It's late June, and paradise suddenly closes in. 329 00:28:35,833 --> 00:28:39,509 {\an1}A plague of mosquitoes emerges. 330 00:28:39,533 --> 00:28:41,176 {\an1}[ Mosquitoes buzzing ] 331 00:28:41,200 --> 00:28:44,876 {\an1}Each one may take just a drop of blood, 332 00:28:44,900 --> 00:28:48,909 {\an1}but the warmer summers favor the insects. 333 00:28:48,933 --> 00:28:52,266 They emerge earlier and breed faster. 334 00:29:02,000 --> 00:29:04,309 The mosquitoes take so much blood 335 00:29:04,333 --> 00:29:07,276 {\an1}and distress the caribou mothers so much 336 00:29:07,300 --> 00:29:09,742 that the herd spends the rest of the summer 337 00:29:09,766 --> 00:29:11,676 {\an1}attempting to avoid them 338 00:29:11,700 --> 00:29:14,942 by searching for somewhere cooler. 339 00:29:14,966 --> 00:29:18,409 Life becomes a daily balancing act of finding 340 00:29:18,433 --> 00:29:20,342 food for yourself 341 00:29:20,366 --> 00:29:24,642 and not being food for mosquitoes. 342 00:29:24,666 --> 00:29:28,109 {\an1}The consequences of the hotter summers may be subtle 343 00:29:28,133 --> 00:29:30,809 {\an1}and complex for the caribou, 344 00:29:30,833 --> 00:29:36,276 {\an1}but the effects to the north are much more obvious. 345 00:29:36,300 --> 00:29:39,542 {\an1}Over the last 40 years, the decline of sea ice 346 00:29:39,566 --> 00:29:41,176 in the Beaufort Sea 347 00:29:41,200 --> 00:29:44,542 is one of the most dramatic changes anywhere. 348 00:29:44,566 --> 00:29:51,709 {\an8}♪♪ 349 00:29:51,733 --> 00:29:56,242 {\an1}One of the animals affected most is the polar bear. 350 00:29:56,266 --> 00:29:58,009 {\an1}During the last ice age, 351 00:29:58,033 --> 00:30:03,276 {\an1}they would probably spend all year on the frozen sea. 352 00:30:03,300 --> 00:30:06,642 {\an1}Since the ice age ended, polar bears hunted seals 353 00:30:06,666 --> 00:30:09,709 on the Arctic ice in winter and spring, 354 00:30:09,733 --> 00:30:12,409 and in late summer, rested on land, 355 00:30:12,433 --> 00:30:15,642 snoozing and living off their fat. 356 00:30:15,666 --> 00:30:23,276 {\an8}♪♪ 357 00:30:23,300 --> 00:30:27,409 Nowadays the ice on the Beaufort Sea is erratic. 358 00:30:27,433 --> 00:30:32,676 {\an1}It melts faster, and the bears arrive early and thinner. 359 00:30:32,700 --> 00:30:40,700 {\an8}♪♪ 360 00:30:46,600 --> 00:30:51,609 {\an1}By July, they are hunting for food along the shore. 361 00:30:51,633 --> 00:30:54,742 {\an1}They're not a huge threat to the caribou herd. 362 00:30:54,766 --> 00:30:58,376 {\an1}They are lumbering on land, and easily overheat. 363 00:30:58,400 --> 00:31:00,566 [ Gulls crying ] 364 00:31:08,466 --> 00:31:10,809 {\an1}Years are more variable now, 365 00:31:10,833 --> 00:31:14,776 {\an1}and polar bears are showing unexpected flexibility. 366 00:31:14,800 --> 00:31:16,876 {\an1}They search for smaller prey 367 00:31:16,900 --> 00:31:19,866 and scavenge or fight over scraps. 368 00:31:23,066 --> 00:31:25,709 The Arctic Refuge is a safe home, 369 00:31:25,733 --> 00:31:29,709 {\an1}but there is no refuge from the outside world. 370 00:31:29,733 --> 00:31:31,676 {\an1}It's too hot for them. 371 00:31:31,700 --> 00:31:35,800 {\an1}The July record here is now 85 degrees Fahrenheit. 372 00:31:39,200 --> 00:31:41,766 {\an1}It's often hardest for a mother. 373 00:31:49,900 --> 00:31:53,842 {\an1}Polar bear cubs are born in midwinter. 374 00:31:53,866 --> 00:31:58,076 {\an1}This coast is one of the most important onshore denning areas 375 00:31:58,100 --> 00:31:59,733 in North America. 376 00:32:05,333 --> 00:32:08,276 These cubs are almost two years old 377 00:32:08,300 --> 00:32:10,400 but still need their mother's milk. 378 00:32:29,300 --> 00:32:33,909 {\an1}Polar bears have declined in the southern Beaufort Sea. 379 00:32:33,933 --> 00:32:37,833 {\an1}There are about half of how many were here 35 years ago. 380 00:32:40,733 --> 00:32:43,609 {\an8}♪♪ 381 00:32:43,633 --> 00:32:46,342 {\an1}These are desperate times. 382 00:32:46,366 --> 00:32:48,809 {\an8}♪♪ 383 00:32:48,833 --> 00:32:50,933 [ Ship horn blares ] 384 00:32:53,033 --> 00:32:57,842 {\an1}North Alaska has the largest oil field in America. 385 00:32:57,866 --> 00:33:05,866 {\an8}♪♪ 386 00:33:08,366 --> 00:33:11,342 {\an1}The base at Prudhoe Bay is next to 387 00:33:11,366 --> 00:33:14,542 the Arctic National Wildlife Refuge. 388 00:33:14,566 --> 00:33:16,176 It's a stark reminder 389 00:33:16,200 --> 00:33:19,009 of the cause of the changing seasons. 390 00:33:19,033 --> 00:33:27,033 {\an8}♪♪ 391 00:33:31,133 --> 00:33:33,909 {\an1}Pipelines extend south 392 00:33:33,933 --> 00:33:37,509 {\an1}and cross several caribou migration routes. 393 00:33:37,533 --> 00:33:45,533 {\an8}♪♪ 394 00:33:46,033 --> 00:33:49,309 {\an1}The polar bears search for food across land 395 00:33:49,333 --> 00:33:52,576 {\an1}now scarred by oil exploration. 396 00:33:52,600 --> 00:33:59,509 {\an8}♪♪ 397 00:33:59,533 --> 00:34:02,009 [ Woman vocalizing ] 398 00:34:02,033 --> 00:34:10,033 {\an8}♪♪ 399 00:34:11,333 --> 00:34:14,942 For the caribou, the green surge is over, 400 00:34:14,966 --> 00:34:16,809 and they are eating willow shrub 401 00:34:16,833 --> 00:34:21,776 {\an1}and searching for anywhere cooler and mosquito free. 402 00:34:21,800 --> 00:34:25,009 {\an1}For some, that means the coast. 403 00:34:25,033 --> 00:34:29,342 {\an1}Others head south into the foothills of the Brooks Range. 404 00:34:29,366 --> 00:34:37,176 {\an8}♪♪ 405 00:34:37,200 --> 00:34:42,200 {\an1}After enduring the heat of July, by late August, it's cooler. 406 00:34:49,900 --> 00:34:54,333 {\an1}A mother and calf turn south, with the protection of the herd. 407 00:34:57,166 --> 00:35:01,642 {\an1}Waiting for them is a grizzly. 408 00:35:01,666 --> 00:35:04,566 Grizzlies and caribou meet each year. 409 00:35:07,200 --> 00:35:11,066 {\an1}The herd is named after the Porcupine River they must cross. 410 00:35:19,700 --> 00:35:24,042 {\an1}The bear's journey here is equally hazardous. 411 00:35:24,066 --> 00:35:28,500 {\an1}In summer, grizzlies hunt all the way to the Arctic Ocean. 412 00:36:00,033 --> 00:36:02,409 {\an1}The Porcupine caribou herd 413 00:36:02,433 --> 00:36:05,133 is heading south into the Brooks Range. 414 00:36:10,900 --> 00:36:13,542 {\an8}♪♪ 415 00:36:13,566 --> 00:36:17,333 Away from the water, the caribou start to relax. 416 00:36:21,466 --> 00:36:23,076 It's a mistake. 417 00:36:23,100 --> 00:36:31,100 {\an8}♪♪ 418 00:36:36,000 --> 00:36:39,909 {\an1}Caribou may be faster than bears on the open plain, 419 00:36:39,933 --> 00:36:42,776 but they must also rest the calves. 420 00:36:42,800 --> 00:36:48,676 {\an8}♪♪ 421 00:36:48,700 --> 00:36:52,409 {\an1}Grizzlies and polar bears are almost the same species 422 00:36:52,433 --> 00:36:55,776 {\an1}and increasingly overlap and interbreed, 423 00:36:55,800 --> 00:36:59,433 {\an1}but grizzlies are a more serious threat to the herd. 424 00:37:01,700 --> 00:37:05,376 The bear has learned to chase off the mothers 425 00:37:05,400 --> 00:37:08,776 {\an1}and then search for calves hiding in the scrub. 426 00:37:08,800 --> 00:37:16,800 {\an8}♪♪ 427 00:37:24,133 --> 00:37:25,833 He's found two. 428 00:37:28,200 --> 00:37:31,676 {\an1}In a moment of indecision... 429 00:37:31,700 --> 00:37:33,300 he loses both. 430 00:37:37,666 --> 00:37:40,976 {\an1}The calf's mother gallops to his side. 431 00:37:41,000 --> 00:37:44,876 It's a huge victory after so much hardship. 432 00:37:44,900 --> 00:37:47,309 [ Bear panting ] 433 00:37:47,333 --> 00:37:52,342 {\an8}♪♪ 434 00:37:52,366 --> 00:37:54,000 {\an1}Though not for the bear. 435 00:38:02,633 --> 00:38:06,909 {\an1}The journey south crosses the Brooks Range in fall. 436 00:38:06,933 --> 00:38:10,609 In spring, this route is blocked by snow, 437 00:38:10,633 --> 00:38:13,809 {\an1}but now they can return straight over the mountains. 438 00:38:13,833 --> 00:38:21,833 {\an8}♪♪ 439 00:38:41,766 --> 00:38:46,409 {\an1}For the calf, this is his first taste of the wider world, 440 00:38:46,433 --> 00:38:50,709 {\an1}with some new characters... Dall sheep. 441 00:38:50,733 --> 00:38:58,442 {\an8}♪♪ 442 00:38:58,466 --> 00:39:03,076 {\an1}They are cousins of bighorns, little bighorns, 443 00:39:03,100 --> 00:39:05,133 {\an1}and mountain specialists. 444 00:39:08,766 --> 00:39:11,309 Like musk ox, they don't migrate, 445 00:39:11,333 --> 00:39:14,409 {\an1}but they do move around the mountains looking for grass 446 00:39:14,433 --> 00:39:17,942 {\an1}and shrubs between the rocks. 447 00:39:17,966 --> 00:39:22,109 {\an1}The ewes give birth to a single lamb in late May. 448 00:39:22,133 --> 00:39:26,509 {\an1}By September, they are all enjoying the last of the summer. 449 00:39:26,533 --> 00:39:32,176 {\an8}♪♪ 450 00:39:32,200 --> 00:39:34,109 [ Sheep bleats ] 451 00:39:34,133 --> 00:39:42,133 {\an8}♪♪ 452 00:39:43,566 --> 00:39:49,676 {\an1}The mothers gather in flocks and watch for wolves and eagles. 453 00:39:49,700 --> 00:39:52,176 {\an1}This is the migration route south, 454 00:39:52,200 --> 00:39:54,809 familiar to more than just caribou. 455 00:39:54,833 --> 00:39:58,476 {\an8}♪♪ 456 00:39:58,500 --> 00:40:01,233 [ Bleating ] 457 00:40:06,333 --> 00:40:14,333 {\an8}♪♪ 458 00:40:16,300 --> 00:40:18,242 {\an1}The fledged golden eagle 459 00:40:18,266 --> 00:40:22,876 has been shadowing the caribou herd south. 460 00:40:22,900 --> 00:40:24,842 {\an1}As the herd turns east, 461 00:40:24,866 --> 00:40:28,176 the caribou face the mountains' wolves. 462 00:40:28,200 --> 00:40:33,309 {\an8}♪♪ 463 00:40:33,333 --> 00:40:37,533 In a small valley, the herd slows to rest. 464 00:40:42,133 --> 00:40:45,266 {\an1}A lone female plans her hunt. 465 00:40:51,366 --> 00:40:53,276 {\an1}She doesn't try to hide. 466 00:40:53,300 --> 00:40:55,976 The mountains are on her side now. 467 00:40:56,000 --> 00:41:04,000 {\an8}♪♪ 468 00:41:19,500 --> 00:41:22,476 {\an1}A calf becomes separated. 469 00:41:22,500 --> 00:41:30,500 {\an8}♪♪ 470 00:41:39,833 --> 00:41:41,209 To its mother, 471 00:41:41,233 --> 00:41:46,366 {\an1}almost home, the trek has lost its meaning, its purpose. 472 00:41:54,333 --> 00:42:00,409 {\an1}The snow geese arrive here from the northernmost Arctic islands. 473 00:42:00,433 --> 00:42:04,576 {\an1}This is an important stopover on their way back to California, 474 00:42:04,600 --> 00:42:07,176 Texas, and Mexico. 475 00:42:07,200 --> 00:42:09,233 [ Squawking ] 476 00:42:11,966 --> 00:42:16,509 {\an1}Snow geese numbers have grown over the last 20 years. 477 00:42:16,533 --> 00:42:18,709 There are now 20 million of them. 478 00:42:18,733 --> 00:42:24,242 {\an8}♪♪ 479 00:42:24,266 --> 00:42:26,642 {\an1}In a world of so much decline, 480 00:42:26,666 --> 00:42:29,876 it's good to know some species are doing well. 481 00:42:29,900 --> 00:42:37,900 {\an8}♪♪ 482 00:42:55,766 --> 00:42:59,976 The autumn storms are sweeping in. 483 00:43:00,000 --> 00:43:02,576 The weather changes very quickly. 484 00:43:02,600 --> 00:43:10,600 {\an8}♪♪ 485 00:43:14,700 --> 00:43:18,876 {\an1}Ptarmigans have been caught in their summer plumage. 486 00:43:18,900 --> 00:43:21,966 They'll turn white to an out-of-date schedule. 487 00:43:26,033 --> 00:43:28,742 As long as the snow isn't too deep, 488 00:43:28,766 --> 00:43:31,976 {\an1}they can feed on willow buds and birch. 489 00:43:32,000 --> 00:43:39,076 {\an8}♪♪ 490 00:43:39,100 --> 00:43:41,909 {\an1}Ptarmigans are here all year. 491 00:43:41,933 --> 00:43:46,276 {\an1}That makes them a reliable target for a red fox. 492 00:43:46,300 --> 00:43:54,300 {\an8}♪♪ 493 00:44:00,233 --> 00:44:02,342 [ Calling ] 494 00:44:02,366 --> 00:44:05,642 {\an1}The many eyes of a flock 495 00:44:05,666 --> 00:44:09,133 and their sharp calls protect them for now. 496 00:44:11,400 --> 00:44:14,042 {\an1}Red foxes are thriving in the Arctic 497 00:44:14,066 --> 00:44:18,442 {\an1}and out-compete Arctic foxes if the weather is milder. 498 00:44:18,466 --> 00:44:26,466 {\an8}♪♪ 499 00:44:34,466 --> 00:44:37,642 By October, the rivers are frozen 500 00:44:37,666 --> 00:44:39,376 {\an1}and are buried under snow. 501 00:44:39,400 --> 00:44:46,809 {\an8}♪♪ 502 00:44:46,833 --> 00:44:50,476 {\an1}The musk ox have to dig for vegetation again. 503 00:44:50,500 --> 00:44:57,276 {\an8}♪♪ 504 00:44:57,300 --> 00:45:01,309 The male musk ox have other concerns. 505 00:45:01,333 --> 00:45:03,009 {\an1}Before winter arrives, 506 00:45:03,033 --> 00:45:06,276 {\an1}they must sort out mating rights to the harem. 507 00:45:06,300 --> 00:45:08,376 {\an1}The rut started in August 508 00:45:08,400 --> 00:45:11,109 and a clear victor has yet to emerge. 509 00:45:11,133 --> 00:45:19,133 {\an8}♪♪ 510 00:45:26,700 --> 00:45:29,809 [ Growling ] 511 00:45:29,833 --> 00:45:37,833 {\an8}♪♪ 512 00:46:03,166 --> 00:46:07,176 {\an1}The musk ox are also related to bighorn sheep, 513 00:46:07,200 --> 00:46:09,142 but are much bigger. 514 00:46:09,166 --> 00:46:11,909 {\an1}Males weigh in at 800 pounds, 515 00:46:11,933 --> 00:46:16,576 {\an1}and their closing speed is close to 60 miles an hour. 516 00:46:16,600 --> 00:46:19,442 Their skulls are heavily reinforced 517 00:46:19,466 --> 00:46:22,176 and the brain protected by fluid. 518 00:46:22,200 --> 00:46:30,200 {\an8}♪♪ 519 00:46:35,466 --> 00:46:39,742 They back away, but only to prepare for combat. 520 00:46:39,766 --> 00:46:46,242 {\an8}♪♪ 521 00:46:46,266 --> 00:46:49,609 {\an1}On the right, the older waits, 522 00:46:49,633 --> 00:46:51,776 then charges. 523 00:46:51,800 --> 00:46:59,800 {\an8}♪♪ 524 00:47:04,400 --> 00:47:07,142 {\an1}There's probably no other animal on Earth 525 00:47:07,166 --> 00:47:09,133 {\an1}that could survive this battle. 526 00:47:12,366 --> 00:47:15,076 {\an1}The winner will now mate with the herd. 527 00:47:15,100 --> 00:47:21,076 {\an8}♪♪ 528 00:47:21,100 --> 00:47:25,742 By October, the land is frozen solid. 529 00:47:25,766 --> 00:47:28,909 [ Gulls crying ] 530 00:47:28,933 --> 00:47:32,242 Two polar bear cubs have survived the summer 531 00:47:32,266 --> 00:47:34,009 {\an1}thanks to their mother. 532 00:47:34,033 --> 00:47:42,033 {\an8}♪♪ 533 00:47:44,033 --> 00:47:46,776 {\an1}The sea won't freeze solid until November, 534 00:47:46,800 --> 00:47:52,109 {\an7}but some coastal bays and river estuaries freeze earlier. 535 00:47:52,133 --> 00:47:56,266 {\an8}It's their playground while they wait. 536 00:47:59,433 --> 00:48:01,176 {\an1}On warm days the surface 537 00:48:01,200 --> 00:48:04,809 starts to melt and becomes slippery 538 00:48:04,833 --> 00:48:08,176 {\an1}and tides weaken the new ice. 539 00:48:08,200 --> 00:48:11,076 {\an1}The surface is still fragile. 540 00:48:11,100 --> 00:48:19,100 {\an8}♪♪ 541 00:48:32,133 --> 00:48:35,642 {\an1}By midwinter, they'll be sniffing out seals 542 00:48:35,666 --> 00:48:39,042 {\an1}in a freezing twilight far from land. 543 00:48:39,066 --> 00:48:45,009 {\an8}♪♪ 544 00:48:45,033 --> 00:48:48,976 {\an1}This is their ice age home at last, 545 00:48:49,000 --> 00:48:53,642 {\an1}a timeless scene that leaves behind a world of change. 546 00:48:53,666 --> 00:49:01,666 {\an8}♪♪ 547 00:49:01,800 --> 00:49:06,233 {\an8}Then the ice breaks, and reality returns. 548 00:49:19,466 --> 00:49:21,876 {\an1}The sea melts and refreezes 549 00:49:21,900 --> 00:49:25,876 and will melt again for two frustrating months. 550 00:49:25,900 --> 00:49:33,900 {\an8}♪♪ 551 00:49:35,300 --> 00:49:38,942 {\an1}The polar bears of the southern Beaufort Sea are doing better 552 00:49:38,966 --> 00:49:42,609 than many others around the Arctic. 553 00:49:42,633 --> 00:49:50,633 {\an8}♪♪ 554 00:49:55,033 --> 00:49:59,176 {\an7}The Arctic National Wildlife Refuge protects the dens, 555 00:49:59,200 --> 00:50:03,409 {\an7}and mothers have become expert scavengers. 556 00:50:03,433 --> 00:50:08,476 {\an7}Their sense of smell is probably the best of all animals. 557 00:50:08,500 --> 00:50:16,500 {\an8}♪♪ 558 00:50:26,933 --> 00:50:29,076 {\an1}And look what they've found. 559 00:50:29,100 --> 00:50:35,176 {\an8}♪♪ 560 00:50:35,200 --> 00:50:39,042 {\an1}It's a bowhead whale... What's left of it. 561 00:50:39,066 --> 00:50:41,400 [ Gulls crying ] 562 00:50:43,966 --> 00:50:46,842 With unpredictable winter ice ahead, 563 00:50:46,866 --> 00:50:50,742 {\an1}this bowhead carcass is a salvation for the family 564 00:50:50,766 --> 00:50:54,376 and for all the local polar bears. 565 00:50:54,400 --> 00:50:56,733 {\an1}They will feed for weeks. 566 00:50:58,533 --> 00:51:04,242 {\an1}Bowhead whales are increasing, maybe thanks to longer summers. 567 00:51:04,266 --> 00:51:07,833 {\an1}Everything is changing, and everything is connected. 568 00:51:10,366 --> 00:51:13,042 {\an1}There is regulated whale hunting here, 569 00:51:13,066 --> 00:51:15,042 and this carcass has actually been left 570 00:51:15,066 --> 00:51:17,600 {\an1}on the beach for the wildlife. 571 00:51:19,800 --> 00:51:22,542 For the polar bears, it's a lifeline, 572 00:51:22,566 --> 00:51:24,200 {\an1}but maybe little more. 573 00:51:26,500 --> 00:51:29,942 They are ice bears, evolved in another world. 574 00:51:29,966 --> 00:51:35,776 {\an8}♪♪ 575 00:51:35,800 --> 00:51:40,209 {\an1}Across millions of years, the Earth has seen huge changes 576 00:51:40,233 --> 00:51:42,476 many times. 577 00:51:42,500 --> 00:51:47,542 {\an1}The most recent was the end of the Ice Age, 12,000 years ago. 578 00:51:47,566 --> 00:51:54,942 {\an8}♪♪ 579 00:51:54,966 --> 00:51:56,742 {\an1}This extraordinary wilderness 580 00:51:56,766 --> 00:52:00,142 {\an1}protects these Ice Age survivors... 581 00:52:00,166 --> 00:52:04,076 The polar bears, musk ox, arctic foxes, 582 00:52:04,100 --> 00:52:06,409 {\an1}and the spectacular caribou, 583 00:52:06,433 --> 00:52:10,842 holding out on the top of the world. 584 00:52:10,866 --> 00:52:15,342 Now, even for them, the ice age may, finally, 585 00:52:15,366 --> 00:52:17,209 be coming to an end. 586 00:52:17,233 --> 00:52:19,576 [ Woman vocalizing ] 587 00:52:19,600 --> 00:52:23,333 {\an8}♪♪ 588 00:52:25,366 --> 00:52:33,366 {\an8}♪♪ 589 00:52:57,766 --> 00:53:01,209 {\an7}To learn more about what you've seen on this "Nature" program, 590 00:53:01,233 --> 00:53:03,209 {\an8}visit pbs.org. 591 00:53:03,233 --> 00:53:11,233 {\an8}♪♪