1 00:00:09,609 --> 00:00:11,076 [stephen fry] the sun. 2 00:00:12,713 --> 00:00:17,116 Fifteen million degrees celsius at its core. 3 00:00:18,085 --> 00:00:20,586 Too close, and you burn. 4 00:00:21,589 --> 00:00:25,491 Too far, you freeze. 5 00:00:26,594 --> 00:00:31,764 But at just the right distance, you get this: 6 00:00:34,000 --> 00:00:37,269 A living, breathing world. 7 00:00:37,337 --> 00:00:38,970 [wind whistling] 8 00:00:38,973 --> 00:00:43,108 Yet life on our planet might be very different 9 00:00:43,176 --> 00:00:45,944 Were it not for one special feature 10 00:00:46,012 --> 00:00:48,547 Of our journey around the sun. 11 00:00:48,615 --> 00:00:50,115 [birds chirping] 12 00:00:51,952 --> 00:00:55,087 No other planet in the known universe 13 00:00:55,155 --> 00:00:58,557 Experiences seasons like our earth. 14 00:00:58,625 --> 00:01:00,459 [squawking] 15 00:01:00,527 --> 00:01:02,027 At this point of our journey, 16 00:01:02,095 --> 00:01:06,799 The northern hemisphere is turning towards the sun, 17 00:01:08,235 --> 00:01:11,270 And winter snow begins to melt. 18 00:01:14,208 --> 00:01:16,241 Just a little at first... 19 00:01:18,512 --> 00:01:20,879 Then more and more... 20 00:01:28,589 --> 00:01:32,758 Until the flow of water becomes truly staggering. 21 00:01:38,698 --> 00:01:41,533 Every year, the returning sun melts 22 00:01:41,535 --> 00:01:45,337 Over 25 million square kilometres of snow 23 00:01:45,405 --> 00:01:47,339 In the northern hemisphere... 24 00:01:52,379 --> 00:01:55,714 Allowing the land to reawaken.. 25 00:01:55,782 --> 00:01:57,649 [birds chirping] 26 00:01:57,717 --> 00:01:59,751 ...And bringing new life. 27 00:02:03,456 --> 00:02:05,690 While in the southern hemisphere, 28 00:02:05,759 --> 00:02:10,095 Life braces itself for far tougher times ahead. 29 00:02:10,097 --> 00:02:11,997 [trumpets] 30 00:02:12,065 --> 00:02:16,235 In more than 60 locations across the globe, 31 00:02:16,303 --> 00:02:20,873 We follow the world's most spectacular animals... 32 00:02:23,677 --> 00:02:25,978 And reveal the struggles... 33 00:02:28,014 --> 00:02:32,484 And opportunities of spring, 34 00:02:34,120 --> 00:02:39,291 The most magical part of our journey around the sun. 35 00:03:10,090 --> 00:03:13,892 This is going to be an extraordinary day. 36 00:03:17,698 --> 00:03:20,465 No matter where you are in the world... 37 00:03:20,467 --> 00:03:23,401 [birds chirping] 38 00:03:23,470 --> 00:03:26,872 ...There will be 12 hours of daylight 39 00:03:28,842 --> 00:03:31,343 And 12 hours of darkness. 40 00:03:34,714 --> 00:03:38,283 The spring equinox has arrived. 41 00:03:40,887 --> 00:03:45,023 Incredibly, there is one animal that can detect 42 00:03:45,091 --> 00:03:48,026 This unique celestial moment. 43 00:03:55,235 --> 00:03:57,202 [gentle rumbling] 44 00:03:59,139 --> 00:04:01,206 A leather-back turtle. 45 00:04:03,811 --> 00:04:07,412 She has a translucent spot on her head 46 00:04:07,480 --> 00:04:10,849 That acts like a skylight, 47 00:04:10,917 --> 00:04:14,286 Letting light shine through her skull, 48 00:04:14,288 --> 00:04:16,788 Directly onto her brain. 49 00:04:18,358 --> 00:04:22,327 And now, after two decades of wandering the oceans, 50 00:04:22,395 --> 00:04:27,065 It compels her to return to the beach where she hatched... 51 00:04:30,870 --> 00:04:33,739 And lay eggs of her own. 52 00:04:48,255 --> 00:04:49,821 [snorting] 53 00:04:54,995 --> 00:04:57,462 As graceful as they are in water, 54 00:04:57,531 --> 00:05:00,899 Leather-backs are poorly adaptd for moving on land. 55 00:05:05,539 --> 00:05:08,573 The largest turtles in the world, 56 00:05:08,641 --> 00:05:13,078 Over half a tonne and as big as a two-seater sof. 57 00:05:14,414 --> 00:05:15,981 [strained breathing] 58 00:05:18,418 --> 00:05:22,587 Every centimetre is won by extreme labour. 59 00:05:31,164 --> 00:05:33,365 It's going to be a tough night. 60 00:05:39,939 --> 00:05:42,107 [snorting] 61 00:05:49,048 --> 00:05:52,617 Her eggs are very sensitive to temperature. 62 00:05:53,787 --> 00:05:55,854 To prevent them from overheating, 63 00:05:55,856 --> 00:05:57,489 She must dig deep. 64 00:05:59,926 --> 00:06:01,993 [laboured breathing] 65 00:06:06,933 --> 00:06:09,734 Finally, after more than an hour, 66 00:06:09,803 --> 00:06:11,370 Her nest is ready. 67 00:06:25,419 --> 00:06:27,919 She lays around 80 eggs, 68 00:06:29,289 --> 00:06:31,957 Each slightly bigger than a golf ball. 69 00:06:34,594 --> 00:06:36,628 [strained breathing] 70 00:06:36,696 --> 00:06:40,599 Now safely buried, they will hatch in two months. 71 00:06:43,303 --> 00:06:46,805 But she won't be here to see her babies emerge. 72 00:06:59,319 --> 00:07:02,988 Exhausted, she must recoup her energy 73 00:07:03,056 --> 00:07:06,892 By going to feed in the richest part of the ocean.. 74 00:07:09,162 --> 00:07:12,831 Which now lies thousands of kilometres north. 75 00:07:16,135 --> 00:07:20,705 As the sun moves further over the northern hemisphere, 76 00:07:20,773 --> 00:07:24,542 Days now become longer than nights. 77 00:07:24,611 --> 00:07:26,077 [birds chirping] 78 00:07:33,520 --> 00:07:36,321 And light fuels growth. 79 00:07:44,030 --> 00:07:46,765 The land bursts with colour. 80 00:07:51,104 --> 00:07:52,571 And surprisingly, 81 00:07:52,639 --> 00:07:56,374 Some of the most spectacular spring blooms of all 82 00:07:56,376 --> 00:07:59,878 Are found right in the middle of the desert. 83 00:08:02,815 --> 00:08:07,819 Since December, day length here has increased by two hours. 84 00:08:09,156 --> 00:08:12,857 The solar energy reaching the ground has almost doubled. 85 00:08:12,926 --> 00:08:14,092 [insects buzzing] 86 00:08:14,160 --> 00:08:17,996 And with the earth still moist from winter rains, 87 00:08:18,064 --> 00:08:21,266 Conditions for growth are perfect. 88 00:08:21,268 --> 00:08:23,034 [birds chirping] 89 00:08:24,804 --> 00:08:27,805 And now these nectar-laden flowers 90 00:08:27,808 --> 00:08:30,809 Attract new life from kilometres around... 91 00:08:36,849 --> 00:08:41,219 Including one of the most beautiful birds in the desert. 92 00:08:46,526 --> 00:08:48,026 [wings thrumming] 93 00:08:51,731 --> 00:08:54,599 A male costa's hummingbird... 94 00:08:58,805 --> 00:09:01,873 Preparing for his busiest time of the year. 95 00:09:07,680 --> 00:09:11,683 Without nectar, he would die of starvation within a few hours. 96 00:09:16,956 --> 00:09:20,959 Hummingbirds have the fastest metabolisms of any animal. 97 00:09:25,599 --> 00:09:29,834 His tiny heart beats more than ten times a second. 98 00:09:34,974 --> 00:09:37,475 And just a few metres away 99 00:09:37,543 --> 00:09:41,046 Is someone that can make it beat faster still: 100 00:09:44,451 --> 00:09:47,552 A female costa's hummingbird. 101 00:09:51,024 --> 00:09:53,425 She may look a little drab, 102 00:09:54,828 --> 00:09:57,862 But she is the object of his desire. 103 00:09:57,930 --> 00:09:59,230 [chirps] 104 00:10:01,034 --> 00:10:05,370 Only problem is, despite his fancy feathers, 105 00:10:05,372 --> 00:10:08,239 She doesn't appear to fancy hi. 106 00:10:08,241 --> 00:10:09,541 [chirping] 107 00:10:11,944 --> 00:10:14,779 Thankfully, he has a trick up his sleeve, 108 00:10:16,116 --> 00:10:18,516 One of nature's most extraordinary 109 00:10:18,584 --> 00:10:20,218 Courtship displays... 110 00:10:25,859 --> 00:10:27,358 [twittering] 111 00:10:27,427 --> 00:10:31,596 ...Best admired with a full frontal. 112 00:10:44,944 --> 00:10:47,912 Positioned at just the right angle to the sun... 113 00:10:49,983 --> 00:10:51,716 With feathers splayed, 114 00:10:53,553 --> 00:10:56,187 He is absolutely dazzling. 115 00:10:59,959 --> 00:11:03,261 Having a purple octopus waved in your face 116 00:11:03,263 --> 00:11:05,897 Might not be your thing, 117 00:11:05,965 --> 00:11:09,901 But the perfection of his plumage shows his quality... 118 00:11:12,072 --> 00:11:13,938 And it works for her. 119 00:11:14,607 --> 00:11:15,907 [twittering] 120 00:11:22,048 --> 00:11:25,250 In just over a month, her chicks will have hatched, 121 00:11:25,318 --> 00:11:28,053 Grown up and flown the nest. 122 00:11:36,162 --> 00:11:40,432 Spring comes early in the deset and it doesn't last long. 123 00:11:42,135 --> 00:11:44,302 [bird hooting] 124 00:11:44,370 --> 00:11:47,972 But in the north, it's now taking hold. 125 00:11:48,041 --> 00:11:49,607 [birds chirping] 126 00:11:49,675 --> 00:11:51,409 The strengthening sun 127 00:11:51,478 --> 00:11:55,279 Fuels billions of tons of new plant growth. 128 00:11:55,282 --> 00:11:56,681 [chirruping] 129 00:11:57,718 --> 00:12:00,384 It sends a pulse of energy 130 00:12:00,453 --> 00:12:02,487 Coursing through the food chain... 131 00:12:02,489 --> 00:12:04,822 [squealing, snorting] 132 00:12:04,825 --> 00:12:08,359 ...Triggering an enormous baby boom. 133 00:12:08,995 --> 00:12:10,862 [chittering] 134 00:12:19,039 --> 00:12:20,505 [growling] 135 00:12:22,308 --> 00:12:23,741 [cheeping] 136 00:12:23,810 --> 00:12:25,977 A surge of easy-to-catch prey 137 00:12:26,045 --> 00:12:28,579 Makes this the ideal time 138 00:12:28,582 --> 00:12:31,249 For hunters to raise their families too. 139 00:12:31,317 --> 00:12:33,585 [whimpering] 140 00:12:44,831 --> 00:12:47,064 East africa, 141 00:12:47,133 --> 00:12:51,770 Home to the planet's greatest population of large carnivores. 142 00:13:01,914 --> 00:13:06,518 Five months ago, this landscape was a predator's paradise. 143 00:13:09,956 --> 00:13:11,890 A million wildebeest, 144 00:13:13,492 --> 00:13:16,160 300,000 zebras 145 00:13:16,229 --> 00:13:19,497 And 200,000 gazelles... 146 00:13:19,499 --> 00:13:21,266 [snorting] 147 00:13:23,202 --> 00:13:25,703 ...Nearly all gone. 148 00:13:25,771 --> 00:13:30,341 And the great migration won't return until summer. 149 00:13:34,381 --> 00:13:37,482 Now, only the locals remain... 150 00:13:41,521 --> 00:13:44,589 Experienced and wary. [snorts] 151 00:13:48,394 --> 00:13:50,995 [squawking] 152 00:13:51,064 --> 00:13:54,732 Spring can be a tough time for a cheetah mum. 153 00:13:54,800 --> 00:13:56,434 [yipping] 154 00:13:56,502 --> 00:14:00,504 Her two six-month-old cubs need to be fed every day, 155 00:14:00,573 --> 00:14:02,307 Or they'll begin to starve. 156 00:14:02,876 --> 00:14:04,275 [snorts] 157 00:14:11,150 --> 00:14:13,251 But she must pick her moment, 158 00:14:15,021 --> 00:14:16,955 Conserve her energy. 159 00:14:18,892 --> 00:14:20,658 [yipping] 160 00:14:22,728 --> 00:14:25,429 The cubs have a different agenda. 161 00:14:25,432 --> 00:14:26,865 [squawking] 162 00:14:28,034 --> 00:14:30,101 Playing is how they learn 163 00:14:30,169 --> 00:14:32,970 Which animals are impossible to catch... 164 00:14:33,039 --> 00:14:34,539 [squawking] 165 00:14:35,942 --> 00:14:37,942 [squealing] 166 00:14:38,010 --> 00:14:40,044 ...And which ones fight back. 167 00:14:42,181 --> 00:14:43,381 [chatters] 168 00:14:43,449 --> 00:14:44,682 [roars] 169 00:14:47,386 --> 00:14:50,655 With practice, they will be able to accelerate 170 00:14:50,723 --> 00:14:53,024 Faster than most sports cars 171 00:14:54,527 --> 00:14:58,462 And reach speeds of over a hundred kilometres an hour. 172 00:14:58,465 --> 00:15:00,465 [yipping] 173 00:15:01,634 --> 00:15:03,334 But not yet. 174 00:15:03,402 --> 00:15:06,938 Right now, they're just being a pain in the... 175 00:15:07,006 --> 00:15:08,072 [growls] 176 00:15:08,641 --> 00:15:09,707 ...Tail. 177 00:15:14,046 --> 00:15:15,747 [yipping] 178 00:15:19,219 --> 00:15:20,885 Enough with the play. 179 00:15:24,357 --> 00:15:26,658 It's time to go to work. 180 00:15:40,806 --> 00:15:42,373 As far as we know, 181 00:15:42,375 --> 00:15:46,511 Cheetahs are the fastest land animals to have ever existed. 182 00:16:01,961 --> 00:16:04,195 They can execute turns 183 00:16:04,263 --> 00:16:09,000 At speeds that would break the legs of other animals. 184 00:16:09,068 --> 00:16:10,234 [antelope bleating] 185 00:16:26,952 --> 00:16:28,119 [bleats] 186 00:16:30,356 --> 00:16:33,691 But, like any high-performance athlete, 187 00:16:33,759 --> 00:16:39,230 Success or failure is separated by the tiniest of margins. 188 00:16:42,034 --> 00:16:45,336 A hunter's dinner is never guaranteed, 189 00:16:46,605 --> 00:16:49,273 Especially at this time of yea. 190 00:16:51,744 --> 00:16:54,979 In many ways, the prey have it easier. 191 00:16:56,282 --> 00:16:59,183 Their food grows everywhere. 192 00:17:00,619 --> 00:17:04,088 But it is dependent on one crucial resource... 193 00:17:04,724 --> 00:17:06,224 [thunder rumbles] 194 00:17:08,260 --> 00:17:09,293 ...Water. 195 00:17:15,735 --> 00:17:17,802 Since winter, the tropical rainband 196 00:17:17,870 --> 00:17:21,172 Has been steadily moving up the continent, 197 00:17:22,675 --> 00:17:26,778 Forming wherever the sun shines hottest on the earth's surface. 198 00:17:28,615 --> 00:17:32,150 It brings life to the dry lands of africa. 199 00:17:33,919 --> 00:17:36,421 But as the rains move north, 200 00:17:37,623 --> 00:17:38,823 Further south... 201 00:17:41,060 --> 00:17:43,528 Conditions are becoming critical. 202 00:17:53,873 --> 00:17:55,573 [low growling] 203 00:17:59,478 --> 00:18:00,945 [snorts] 204 00:18:04,416 --> 00:18:06,050 [trumpets] 205 00:18:06,118 --> 00:18:09,053 The water holes are shrinking, 206 00:18:10,790 --> 00:18:12,056 Getting crowded... 207 00:18:13,159 --> 00:18:14,358 [grunts] 208 00:18:16,329 --> 00:18:17,562 [trumpets] 209 00:18:18,531 --> 00:18:20,865 ...And more dangerous. 210 00:18:27,273 --> 00:18:29,974 Even the elephants are vulnerable... 211 00:18:32,878 --> 00:18:35,012 Especially the youngsters. 212 00:18:36,415 --> 00:18:37,882 [trumpets] 213 00:18:40,986 --> 00:18:42,987 [low growl] 214 00:18:42,989 --> 00:18:46,490 The old matriarch, leader of this group, 215 00:18:46,559 --> 00:18:49,326 Knows it's time to move on. 216 00:18:52,298 --> 00:18:55,666 She has made many journeys in search of water 217 00:18:55,734 --> 00:18:57,869 In her 50 years 218 00:18:58,972 --> 00:19:01,038 And can even remember routes made 219 00:19:01,106 --> 00:19:04,241 During extreme droughts decades ago. 220 00:19:04,310 --> 00:19:06,010 [trumpeting] [low growling] 221 00:19:07,980 --> 00:19:11,916 And now this four-month-old bay must learn the way 222 00:19:11,918 --> 00:19:14,785 As he begins his first migration. 223 00:19:17,423 --> 00:19:21,859 Indeed, much of an elephant's behaviour is learned. 224 00:19:24,096 --> 00:19:25,963 From birth to adulthood, 225 00:19:26,031 --> 00:19:29,667 Their brains almost triple in size, 226 00:19:29,669 --> 00:19:34,171 The greatest increase of any animal apart from us. 227 00:19:34,240 --> 00:19:35,373 [trumpeting] 228 00:19:36,476 --> 00:19:39,110 The good times are over. 229 00:19:41,380 --> 00:19:46,050 Ahead, only a thirsty, gruelling March. 230 00:19:46,118 --> 00:19:48,786 [low growling] 231 00:19:51,657 --> 00:19:54,525 [birds chirping] 232 00:19:54,593 --> 00:19:58,763 The red-billed quelea are also heading off. 233 00:20:01,000 --> 00:20:06,070 They follow the rains and the pulse of fresh grass seed, 234 00:20:07,273 --> 00:20:10,608 And they do so in their millions... 235 00:20:10,676 --> 00:20:12,009 [chirping] 236 00:20:13,846 --> 00:20:17,815 ...The most abundant wild bird in the world. 237 00:20:20,119 --> 00:20:24,888 The key to their success is a super-fast breeding cycle, 238 00:20:24,957 --> 00:20:26,457 Little more than three weeks 239 00:20:26,525 --> 00:20:28,993 From laying eggs to chicks flying, 240 00:20:30,829 --> 00:20:33,898 Ready to leave when conditions get tough. 241 00:20:46,445 --> 00:20:51,315 In the far south, the darkness is creeping in... 242 00:20:53,686 --> 00:20:56,254 The sun sinking lower... 243 00:20:57,623 --> 00:20:59,624 The land growing colder. 244 00:21:03,929 --> 00:21:05,329 [penguins squawking] 245 00:21:09,702 --> 00:21:10,901 [peeps] 246 00:21:10,969 --> 00:21:15,339 This four-month-old king pengun chick is stuck here. 247 00:21:17,976 --> 00:21:20,477 She won't be ready to leave the island 248 00:21:20,546 --> 00:21:22,346 For another eight months. 249 00:21:24,250 --> 00:21:27,685 So she must prepare for the coming cold. 250 00:21:30,756 --> 00:21:34,958 Since hatching, she's grown from a tiny naked chick 251 00:21:35,027 --> 00:21:37,828 Weighing less than 250 grams, 252 00:21:37,896 --> 00:21:43,234 Into this plump, downy youngstr of over 12 kilos. 253 00:21:46,638 --> 00:21:47,905 Just as well. 254 00:21:47,973 --> 00:21:51,041 It's the coldest day of the year so far... 255 00:21:54,080 --> 00:21:57,648 And something new and strange is happening. 256 00:22:00,152 --> 00:22:01,886 [chirps] 257 00:22:16,902 --> 00:22:18,336 [chirps] 258 00:22:24,543 --> 00:22:27,411 Curiosity gets the better of her. 259 00:22:40,926 --> 00:22:42,126 [chirps] 260 00:22:44,163 --> 00:22:45,896 [penguins squawking] 261 00:22:48,267 --> 00:22:50,868 The nasty side of town. 262 00:22:53,472 --> 00:22:56,307 The source of all this flying fluff... 263 00:22:58,043 --> 00:22:59,443 Not snow, 264 00:23:00,946 --> 00:23:04,515 Manky, moulting macaroni penguins. 265 00:23:05,551 --> 00:23:07,251 [squawking continues] 266 00:23:20,365 --> 00:23:22,767 And there's something else her. 267 00:23:25,004 --> 00:23:26,303 Monsters. 268 00:23:26,371 --> 00:23:27,905 [rasping] 269 00:23:27,973 --> 00:23:30,741 These are giant petrels... 270 00:23:33,679 --> 00:23:37,648 A metre tall and as heavy as a christmas turkey. 271 00:23:38,717 --> 00:23:40,851 [rasping, squawking] 272 00:23:40,919 --> 00:23:45,456 The stress of moulting makes some macaronis weak. 273 00:23:45,524 --> 00:23:47,625 [grunting] 274 00:23:48,461 --> 00:23:50,795 But if you show weakness here.. 275 00:23:51,430 --> 00:23:53,464 [chittering] 276 00:23:53,532 --> 00:23:55,866 ...There is no mercy. 277 00:23:55,934 --> 00:23:57,668 [petrels rasping] [penguins squawking] 278 00:23:57,736 --> 00:24:00,571 [petrels bleating] 279 00:24:05,911 --> 00:24:07,311 [penguins squawking] 280 00:24:17,890 --> 00:24:22,025 Giant petrels don't miss any opportunity. 281 00:24:22,094 --> 00:24:23,394 [squawking] 282 00:24:27,566 --> 00:24:29,566 Against these relentless killers, 283 00:24:29,569 --> 00:24:32,203 A chick doesn't stand a chance. 284 00:24:32,938 --> 00:24:36,139 [rasping] 285 00:24:36,208 --> 00:24:38,542 And she's just been spotted. 286 00:24:42,648 --> 00:24:46,917 Time to get back to the protection of her own kind. 287 00:24:48,854 --> 00:24:50,588 [rasping] 288 00:24:51,356 --> 00:24:52,723 [chick chirping] 289 00:24:52,791 --> 00:24:56,060 Her nemesis is coming for her. 290 00:25:01,867 --> 00:25:03,500 [penguins squawking] 291 00:25:03,569 --> 00:25:05,069 [petrel caws] 292 00:25:07,406 --> 00:25:09,373 [cheeping] 293 00:25:15,915 --> 00:25:17,248 [squawking] 294 00:25:21,753 --> 00:25:22,853 [squawks] 295 00:25:24,323 --> 00:25:26,223 [penguins squawking] 296 00:25:30,530 --> 00:25:33,964 But the giant petrel has underestimated the kings. 297 00:25:34,032 --> 00:25:35,332 [cawing] 298 00:25:39,037 --> 00:25:41,538 Twice as big as the macaronis, 299 00:25:41,607 --> 00:25:44,542 They can stand up to this bull. 300 00:25:47,579 --> 00:25:49,780 [penguins squawking] [cawing] 301 00:25:51,851 --> 00:25:53,617 [rasping] 302 00:25:57,757 --> 00:26:00,958 It's all too much for the giant petrel. 303 00:26:01,026 --> 00:26:03,127 [squawking] 304 00:26:07,199 --> 00:26:10,100 Finally, the chick can relax. 305 00:26:13,138 --> 00:26:15,472 But not too much. 306 00:26:15,474 --> 00:26:21,378 Soon, her parents will be gone for weeks, even months on end. 307 00:26:21,446 --> 00:26:26,183 As the water gets colder, the ocean currents shift, 308 00:26:26,251 --> 00:26:29,453 And feeding areas move further away. 309 00:26:31,557 --> 00:26:34,325 She will grow hungrier, weaker... 310 00:26:35,894 --> 00:26:38,896 [chirping] ...And she'll be alone. 311 00:26:48,974 --> 00:26:52,076 While conditions in the south grow harsher, 312 00:26:53,379 --> 00:26:57,615 The northern hemisphere is in the full flush of spring. 313 00:27:08,594 --> 00:27:12,062 And here, in this seasonal rain forest, 314 00:27:12,130 --> 00:27:16,367 The fresh growth feeds all kinds of animals... 315 00:27:17,403 --> 00:27:19,569 [leaves rustling] 316 00:27:19,638 --> 00:27:24,842 ...Including one of the most striking monkeys on the planet. 317 00:27:49,534 --> 00:27:51,902 Red-shanked doucs. 318 00:27:56,742 --> 00:28:02,045 Timed with the burst of fresh spring leaves and flowers, 319 00:28:02,114 --> 00:28:05,349 These doucs are having a baby boom of their own. 320 00:28:09,955 --> 00:28:11,755 Only four years old, 321 00:28:11,823 --> 00:28:14,792 This is the youngest mum in the community... 322 00:28:16,862 --> 00:28:20,097 And this is her first baby, 323 00:28:21,900 --> 00:28:23,934 Just days old. 324 00:28:33,678 --> 00:28:37,014 Right now, it's a worrying time for mum. 325 00:28:39,284 --> 00:28:41,885 Newborns make easy targets... 326 00:28:43,956 --> 00:28:46,690 For all kinds of predators. 327 00:29:01,940 --> 00:29:03,607 [hissing] 328 00:29:13,485 --> 00:29:16,920 But too much protection can be stifling. 329 00:29:22,060 --> 00:29:24,494 He needs to learn key skills, 330 00:29:24,563 --> 00:29:27,765 Like how to move through the forest. 331 00:29:31,403 --> 00:29:32,603 [chitters] 332 00:29:34,940 --> 00:29:39,109 Doucs make some of the longest leaps of all monkeys, 333 00:29:39,177 --> 00:29:41,845 Frequently exceeding ten metre. 334 00:29:45,684 --> 00:29:48,986 You can't do this without a lot of practice. 335 00:29:54,059 --> 00:29:57,761 Sometimes, a mum has to let go. 336 00:30:09,541 --> 00:30:14,178 We see spring as a time of relief after a long winter. 337 00:30:16,715 --> 00:30:21,084 Yet, for many animals, this is a time of great stress. 338 00:30:22,488 --> 00:30:24,154 [chitters] 339 00:30:24,222 --> 00:30:29,960 Never will their babies be more needy and more vulnerable, 340 00:30:31,396 --> 00:30:34,565 And never will parents have to be more vigilant. 341 00:30:37,203 --> 00:30:41,438 But all a mum can do is take it one day at a time. 342 00:30:48,747 --> 00:30:50,614 [insects chirping] 343 00:30:56,288 --> 00:30:58,655 At least she's bringing up baby 344 00:30:58,723 --> 00:31:00,624 In the relative comfort of the tropics. 345 00:31:06,765 --> 00:31:10,500 A little further north, just beyond the himalayas, 346 00:31:10,568 --> 00:31:12,336 It's a different story. 347 00:31:12,938 --> 00:31:14,538 [wind whistling] 348 00:31:22,080 --> 00:31:23,280 [squawking] 349 00:31:23,348 --> 00:31:25,549 The tibetan plateau. 350 00:31:28,353 --> 00:31:32,322 Covering nearly two and a half million square kilometres 351 00:31:32,324 --> 00:31:35,692 And averaging over 4,000 metres high, 352 00:31:35,760 --> 00:31:40,397 It's the largest and highest plateau in the world. 353 00:31:43,668 --> 00:31:47,070 With little more than half the oxygen at sea level, 354 00:31:47,072 --> 00:31:49,640 The air leaves you gasping. 355 00:31:51,109 --> 00:31:53,210 Winter temperatures can plummet 356 00:31:53,278 --> 00:31:55,979 To minus 20 degrees celsius. 357 00:31:57,048 --> 00:31:59,215 [birds chirping] 358 00:31:59,218 --> 00:32:02,986 Not many animals have adapted to life up here. 359 00:32:06,959 --> 00:32:08,992 This is one of the few. 360 00:32:10,595 --> 00:32:12,429 A tibetan fox. 361 00:32:14,499 --> 00:32:17,300 A mere two-and-a-half million years 362 00:32:17,369 --> 00:32:21,038 Set it apart from our red fox, 363 00:32:21,106 --> 00:32:25,309 Yet it's enough to have evolved an extraordinarily wide gape... 364 00:32:27,846 --> 00:32:29,546 [panting] 365 00:32:32,917 --> 00:32:34,651 ...An adaptation for a diet 366 00:32:34,653 --> 00:32:38,188 Consisting almost entirely of these animals. 367 00:32:38,256 --> 00:32:40,223 [chittering] 368 00:32:43,261 --> 00:32:46,196 Thanks to a surge of spring breeding, 369 00:32:46,264 --> 00:32:49,065 Plateau pika are everywhere. 370 00:32:49,134 --> 00:32:50,233 [shrill chirp] 371 00:32:50,301 --> 00:32:53,603 But they have hundreds of bolt-holes. 372 00:32:53,671 --> 00:32:54,638 [sniffing] 373 00:32:57,476 --> 00:32:58,775 [panting] 374 00:32:59,878 --> 00:33:02,012 To catch one, you have to be... 375 00:33:05,684 --> 00:33:07,250 Patient. 376 00:33:14,826 --> 00:33:16,026 [shrill chirp] 377 00:33:17,962 --> 00:33:18,962 [shrill chirps] 378 00:33:23,802 --> 00:33:25,068 [shrill chirp] 379 00:33:29,174 --> 00:33:30,374 [shrill chirp] 380 00:33:33,011 --> 00:33:34,845 [sniffing] 381 00:33:43,889 --> 00:33:44,888 [shrill chirp] 382 00:33:51,930 --> 00:33:53,630 [chittering] 383 00:33:55,133 --> 00:33:58,568 A lot of work for such a small snack. 384 00:34:00,639 --> 00:34:02,939 And she's not even going to eat it. 385 00:34:03,608 --> 00:34:05,208 [whimpering] 386 00:34:08,246 --> 00:34:11,681 It's for her three eight-week-old cubs. 387 00:34:19,825 --> 00:34:24,661 In fox families, fathers usually stick around to help. 388 00:34:27,800 --> 00:34:31,268 But dad hasn't been seen for weeks. 389 00:34:35,807 --> 00:34:38,174 Up here, conditions are so harsh, 390 00:34:38,243 --> 00:34:40,677 Lives are often cut short. 391 00:34:42,881 --> 00:34:47,050 Keeping the family fed is now a real struggle. 392 00:34:50,322 --> 00:34:51,555 [yelping] 393 00:34:55,460 --> 00:34:57,560 By the time the cubs are up... 394 00:34:57,629 --> 00:34:59,028 [chittering] 395 00:34:59,097 --> 00:35:01,431 ...Mum's already out hunting. 396 00:35:02,267 --> 00:35:04,134 [snarling] 397 00:35:06,137 --> 00:35:09,072 All this play is hungry work. 398 00:35:13,011 --> 00:35:17,380 But for some reason, breakfast is late. 399 00:35:22,487 --> 00:35:23,987 [whimpers] 400 00:35:26,024 --> 00:35:30,727 Constantly sprinting after prey over potholed ground 401 00:35:30,795 --> 00:35:32,629 Has taken its toll. 402 00:35:38,736 --> 00:35:43,240 An injury as serious as this could stop her hunting. 403 00:35:47,646 --> 00:35:52,149 And that means starvation for the whole family. 404 00:35:57,856 --> 00:36:00,423 [thunder rumbling] 405 00:36:25,316 --> 00:36:29,819 Though clearly in pain, mum is off hunting again. 406 00:36:35,760 --> 00:36:39,029 With cubs to feed, she has no choice. 407 00:36:40,965 --> 00:36:42,699 [chittering] 408 00:36:42,767 --> 00:36:44,467 [shrill chirp] 409 00:36:46,037 --> 00:36:50,907 But sometimes, adversity brings out the best in you. 410 00:37:03,488 --> 00:37:04,921 [chittering] 411 00:37:06,190 --> 00:37:07,390 [shrill chirp] 412 00:37:09,595 --> 00:37:11,595 [squealing] 413 00:37:22,407 --> 00:37:23,773 [pika squealing] 414 00:37:23,841 --> 00:37:26,810 She's found her a-game. 415 00:37:37,289 --> 00:37:38,555 [squealing] 416 00:37:38,623 --> 00:37:41,324 Perhaps her luck is returning. 417 00:37:49,635 --> 00:37:53,703 Thanks to mum's extraordinary determination, 418 00:37:53,772 --> 00:37:56,940 The cubs should keep growing strong. 419 00:37:58,744 --> 00:38:01,044 With so many mouths to feed, 420 00:38:01,046 --> 00:38:05,382 Spring can be the most challenging time of year. 421 00:38:18,396 --> 00:38:24,000 This cheetah mum desperately needs a change in fortune. 422 00:38:32,777 --> 00:38:34,277 [cheetah roaring] 423 00:38:46,124 --> 00:38:48,325 [impala grunting] 424 00:38:55,533 --> 00:38:57,801 No matter how hard she tries, 425 00:38:59,437 --> 00:39:02,238 It always ends in frustration. 426 00:39:08,112 --> 00:39:11,180 Mum is exhausted. 427 00:39:11,183 --> 00:39:14,317 She can't afford any more failures. 428 00:39:17,589 --> 00:39:19,756 When the migration comes in August, 429 00:39:19,824 --> 00:39:23,226 There will be easier prey. 430 00:39:24,529 --> 00:39:27,764 But right now, times are tough. 431 00:39:31,903 --> 00:39:33,570 [low growling] 432 00:39:36,141 --> 00:39:39,109 Hyenas will kill cheetah cubs. 433 00:39:40,011 --> 00:39:41,578 [hyena snarling] 434 00:39:42,914 --> 00:39:46,416 They're too big to beat in a fight. 435 00:39:49,420 --> 00:39:52,155 The whole family has to be very careful. 436 00:39:55,560 --> 00:39:59,362 All she can do is stay by her cubs 437 00:39:59,364 --> 00:40:01,998 And hope the danger passes. 438 00:40:10,775 --> 00:40:14,778 The threat from lions and hyenas is constant. 439 00:40:16,180 --> 00:40:18,114 But she can't hide forever. 440 00:40:19,050 --> 00:40:21,184 Her family needs to eat. 441 00:40:26,858 --> 00:40:29,092 A male impala. 442 00:40:32,497 --> 00:40:36,599 Cheetahs usually avoid such large, heavily armed prey. 443 00:40:37,903 --> 00:40:40,670 The risk of injury is just too high. 444 00:40:47,545 --> 00:40:49,546 But not for this mum. 445 00:41:03,160 --> 00:41:04,327 [bleating] 446 00:41:28,453 --> 00:41:29,886 [squeals] 447 00:41:32,190 --> 00:41:34,390 [cubs growling] 448 00:41:44,702 --> 00:41:48,638 For the first time, her cubs actually help. 449 00:42:04,189 --> 00:42:07,590 Around 80% of cheetah cubs here 450 00:42:07,658 --> 00:42:11,027 Succumb to predators or starvation 451 00:42:11,095 --> 00:42:13,696 Before they reach their first birthday. 452 00:42:16,201 --> 00:42:19,102 Her cubs still have a long way to go, 453 00:42:20,671 --> 00:42:24,807 But with every kill, every passing day, 454 00:42:25,776 --> 00:42:28,411 Their chances improve. 455 00:42:44,996 --> 00:42:48,464 Spring in the north is drawing to an end. 456 00:42:51,535 --> 00:42:53,970 But here, on this beach, 457 00:42:54,038 --> 00:42:57,674 It still has one final wonder to offer. 458 00:43:20,098 --> 00:43:24,434 For eight weeks, the leather-back eggs 459 00:43:24,502 --> 00:43:27,370 Have been gently incubated by the sun. 460 00:43:30,574 --> 00:43:35,111 Now the baby turtles are beginning their own journe. 461 00:43:37,248 --> 00:43:41,184 But everything will depend on the next few minutes. 462 00:43:42,253 --> 00:43:43,252 [squawks] 463 00:43:45,056 --> 00:43:46,823 [squawking] 464 00:43:51,228 --> 00:43:54,797 Black vultures have been waiting for this moment. 465 00:44:13,517 --> 00:44:14,784 [squawking] 466 00:44:20,725 --> 00:44:24,460 Their mum's sacrifice, her toil on the beach, 467 00:44:24,528 --> 00:44:26,396 May come to nothing. 468 00:44:28,065 --> 00:44:29,999 [squawking] 469 00:44:33,104 --> 00:44:36,072 But if this hatchling can make it to the sea, 470 00:44:36,140 --> 00:44:40,343 The odds of reaching adulthood rise dramatically. 471 00:45:02,366 --> 00:45:05,635 He's passed his first trial. 472 00:45:07,338 --> 00:45:12,908 With luck, he may go on to live for over 50 years 473 00:45:12,977 --> 00:45:16,913 And travel tens of thousands of kilometres of ocean. 474 00:45:20,718 --> 00:45:25,387 Within a month, the leather-bak turtles that nested in trinidad 475 00:45:25,456 --> 00:45:27,289 Will make an epic journey 476 00:45:27,292 --> 00:45:29,926 To the northernmost parts of the atlantic. 477 00:45:32,396 --> 00:45:36,265 Soon, the sun will deliver more energy here 478 00:45:36,333 --> 00:45:38,701 Than the hottest part of the tropics. 479 00:45:38,769 --> 00:45:40,403 [mooing] 480 00:45:43,174 --> 00:45:46,709 We are about to begin summer... 481 00:45:48,746 --> 00:45:51,213 A season of extremes... 482 00:45:51,282 --> 00:45:53,149 [chirping] 483 00:45:53,217 --> 00:45:55,117 ...That brings new dangers... 484 00:45:55,186 --> 00:45:57,419 [braying] 485 00:45:57,488 --> 00:45:59,655 ...But also great riches... 486 00:46:01,292 --> 00:46:02,391 [sharp squeal] 487 00:46:03,961 --> 00:46:08,531 ...In the hottest and most intense part 488 00:46:08,599 --> 00:46:11,601 Of our year on planet earth.