1 00:00:31,963 --> 00:00:33,603 Namibia, 2 00:00:33,603 --> 00:00:35,123 Southern Africa. 3 00:00:42,843 --> 00:00:45,683 A vast, dried-up lakebed... 4 00:00:57,043 --> 00:00:58,883 ...where temperatures can reach 5 00:00:58,883 --> 00:01:01,163 almost 50 degrees Celsius. 6 00:01:12,963 --> 00:01:14,843 Overheating 7 00:01:14,843 --> 00:01:16,723 is dangerous for all. 8 00:01:24,443 --> 00:01:27,763 Nonetheless, in this cauldron of heat... 9 00:01:30,883 --> 00:01:33,923 ...mammals have found a way to survive. 10 00:01:44,243 --> 00:01:45,963 Across the planet, 11 00:01:45,963 --> 00:01:49,163 {\an8}mammals have learnt how to deal with heat... 12 00:01:51,163 --> 00:01:53,443 ...in the most remarkable ways. 13 00:02:11,683 --> 00:02:14,563 The Serra da Capivara in Brazil. 14 00:02:15,763 --> 00:02:18,763 A world of harsh, dry forest... 15 00:02:23,003 --> 00:02:25,363 ...and scorched cliff faces. 16 00:02:30,043 --> 00:02:32,803 Here, the dry season lasts 17 00:02:32,803 --> 00:02:34,803 for up to seven months. 18 00:02:37,643 --> 00:02:40,043 And what little rain that falls 19 00:02:40,043 --> 00:02:41,803 quickly disappears. 20 00:02:44,323 --> 00:02:45,723 Despite this, 21 00:02:45,723 --> 00:02:48,083 one mammal has made it home. 22 00:02:50,203 --> 00:02:53,443 A family of bearded capuchins. 23 00:03:03,883 --> 00:03:05,243 They have spent the night 24 00:03:05,243 --> 00:03:07,363 high up on the cliff faces, 25 00:03:07,363 --> 00:03:10,323 safe from any predators below. 26 00:03:13,043 --> 00:03:14,443 It may be early, 27 00:03:14,443 --> 00:03:17,363 but already temperatures are beginning to soar. 28 00:03:20,043 --> 00:03:21,123 The troop 29 00:03:21,123 --> 00:03:23,123 needs to find water. 30 00:03:25,683 --> 00:03:27,883 And none need it more 31 00:03:27,883 --> 00:03:29,043 than a mother. 32 00:03:30,643 --> 00:03:31,723 Without it, 33 00:03:31,723 --> 00:03:33,803 she won't be able to produce the milk 34 00:03:33,803 --> 00:03:35,643 essential for her young baby. 35 00:03:37,803 --> 00:03:41,243 But first, they must make the treacherous journey 36 00:03:41,243 --> 00:03:43,283 down to the forest floor. 37 00:03:58,243 --> 00:04:00,883 The newborn must hold on tight. 38 00:04:06,523 --> 00:04:09,203 Others forge ahead. 39 00:04:29,363 --> 00:04:32,283 For the first to reach the forest floor... 40 00:04:34,963 --> 00:04:37,443 ...the last few cashew fruit 41 00:04:37,443 --> 00:04:40,323 provide some welcome sustenance. 42 00:04:46,363 --> 00:04:49,403 But there's not enough to go around. 43 00:04:50,763 --> 00:04:53,243 Mother and baby must go without. 44 00:04:57,043 --> 00:04:58,843 At nearly 40 degrees, 45 00:04:58,843 --> 00:05:01,243 the heat is relentless. 46 00:05:10,363 --> 00:05:11,683 Desperate, 47 00:05:11,683 --> 00:05:13,563 the troop look for anything 48 00:05:13,563 --> 00:05:15,403 that might contain water. 49 00:05:32,083 --> 00:05:34,803 Could the trees provide the solution? 50 00:05:43,603 --> 00:05:45,163 Hidden in some trunks, 51 00:05:45,163 --> 00:05:47,443 there is a little water, 52 00:05:47,443 --> 00:05:49,843 left over from the last rains. 53 00:05:57,043 --> 00:05:58,403 But reaching it 54 00:05:58,403 --> 00:06:00,563 is a real monkey puzzle. 55 00:06:06,483 --> 00:06:08,403 Mammals, however, 56 00:06:08,403 --> 00:06:11,283 are experts at solving problems. 57 00:06:14,563 --> 00:06:17,683 An older male tries a different approach. 58 00:06:22,683 --> 00:06:24,563 Perhaps a bit more brains 59 00:06:24,563 --> 00:06:26,323 and a little less brawn. 60 00:06:39,443 --> 00:06:42,883 A stick produces a dribble of success. 61 00:06:46,883 --> 00:06:49,843 Having watched all the others try, 62 00:06:49,843 --> 00:06:52,563 the mother finally gets her turn. 63 00:07:30,883 --> 00:07:33,603 Her tail acts like a sponge... 64 00:07:34,723 --> 00:07:36,123 ...soaking up any water 65 00:07:36,123 --> 00:07:38,043 that has collected in the trunk. 66 00:07:42,163 --> 00:07:45,243 Being able to tap these hidden wells 67 00:07:45,243 --> 00:07:47,243 is more than just a clever trick. 68 00:07:49,283 --> 00:07:51,723 It's a life-saving lesson... 69 00:07:54,203 --> 00:07:57,483 ...and one the rest of her family quickly learn. 70 00:08:02,283 --> 00:08:04,963 Their ability to solve such problems 71 00:08:04,963 --> 00:08:07,283 will help the troop survive 72 00:08:07,283 --> 00:08:09,243 these long, hot, dry months. 73 00:08:15,443 --> 00:08:17,643 And, finally, the newborn 74 00:08:17,643 --> 00:08:20,283 can get a much-needed drink of its own. 75 00:08:32,323 --> 00:08:34,043 But there are places 76 00:08:34,043 --> 00:08:37,003 that are even hotter and even drier. 77 00:08:41,643 --> 00:08:43,123 Australia - 78 00:08:43,123 --> 00:08:46,243 the driest inhabited continent on Earth, 79 00:08:46,243 --> 00:08:49,283 with almost a million square miles of desert. 80 00:08:53,643 --> 00:08:57,523 A furnace where water is almost impossible to find. 81 00:09:10,043 --> 00:09:11,963 An Arabian camel. 82 00:09:13,323 --> 00:09:17,963 Introduced in the 1800s by early explorers, 83 00:09:17,963 --> 00:09:20,963 it's estimated that as many as one million 84 00:09:20,963 --> 00:09:22,763 now roam the outback. 85 00:09:30,843 --> 00:09:33,563 For this lone male in search of a mate, 86 00:09:33,563 --> 00:09:35,243 desert plants 87 00:09:35,243 --> 00:09:37,763 provide a few slim pickings. 88 00:09:40,923 --> 00:09:42,723 Any surplus nutrients 89 00:09:42,723 --> 00:09:45,963 can be stored in his most famous feature... 90 00:09:48,083 --> 00:09:49,483 ...his hump. 91 00:09:51,003 --> 00:09:52,483 Full of fat, 92 00:09:52,483 --> 00:09:54,563 it's a built-in energy store 93 00:09:54,563 --> 00:09:56,603 that can be tapped when needed. 94 00:10:01,763 --> 00:10:04,763 And as long as he can find food, 95 00:10:04,763 --> 00:10:08,083 he can go without drinking for months. 96 00:10:32,043 --> 00:10:33,603 At last, 97 00:10:33,603 --> 00:10:35,603 what he's been looking for. 98 00:10:39,243 --> 00:10:41,723 A herd of females. 99 00:10:56,363 --> 00:10:57,443 It's important 100 00:10:57,443 --> 00:10:59,683 that he makes a good first impression. 101 00:11:08,083 --> 00:11:10,763 And he has a special way of doing so... 102 00:11:13,363 --> 00:11:14,963 ...with a dulla. 103 00:11:25,043 --> 00:11:27,403 This inflatable sac 104 00:11:27,403 --> 00:11:29,643 is unique to camels, 105 00:11:29,643 --> 00:11:32,403 and accompanied by loud gurgling... 106 00:11:33,563 --> 00:11:36,203 ...is his way of attracting females. 107 00:11:53,283 --> 00:11:55,483 Has he done enough to impress? 108 00:12:01,283 --> 00:12:02,683 Apparently not. 109 00:12:02,683 --> 00:12:05,963 A raised tail is a polite way of saying, 110 00:12:05,963 --> 00:12:07,443 "No, thank you." 111 00:12:13,043 --> 00:12:15,723 Not so easy after all. 112 00:12:18,643 --> 00:12:20,443 Could she be the one? 113 00:12:29,403 --> 00:12:30,883 Looking good! 114 00:12:40,163 --> 00:12:42,163 Bad luck, Romeo. 115 00:12:46,043 --> 00:12:48,283 Despite his best efforts, 116 00:12:48,283 --> 00:12:50,443 it's not been his day. 117 00:12:57,083 --> 00:12:59,043 Camels have overcome 118 00:12:59,043 --> 00:13:01,643 the desert's greatest test - 119 00:13:01,643 --> 00:13:03,163 its lack of water. 120 00:13:05,603 --> 00:13:08,043 {\an8}But this is not the only challenge 121 00:13:08,043 --> 00:13:09,363 {\an8}faced by mammals 122 00:13:09,363 --> 00:13:11,763 {\an8}in hot and arid conditions. 123 00:13:13,963 --> 00:13:15,523 {\an8}Just as dangerous 124 00:13:15,523 --> 00:13:18,043 {\an8}is the risk of overheating. 125 00:13:34,363 --> 00:13:35,883 Sifaka lemurs... 126 00:13:36,923 --> 00:13:38,283 ...in one of the hottest 127 00:13:38,283 --> 00:13:41,043 and driest places in Madagascar. 128 00:13:44,203 --> 00:13:46,643 The trees provide some shade... 129 00:13:47,563 --> 00:13:50,523 ...and a little relief from the burning sun. 130 00:13:59,603 --> 00:14:01,363 But with midday temperatures 131 00:14:01,363 --> 00:14:03,923 that can exceed 45 degrees... 132 00:14:05,363 --> 00:14:08,843 ...the heat up here soon becomes unbearable... 133 00:14:17,883 --> 00:14:20,123 ...especially for the babies... 134 00:14:21,203 --> 00:14:23,843 ...the most vulnerable members of the group. 135 00:14:33,123 --> 00:14:34,683 But sifaka 136 00:14:34,683 --> 00:14:36,603 have an unusual and clever way 137 00:14:36,603 --> 00:14:38,043 to cool down... 138 00:14:43,043 --> 00:14:46,403 {\an8}...if only they can find the right tree. 139 00:15:17,203 --> 00:15:19,123 And once they have... 140 00:15:23,443 --> 00:15:24,923 ...they hug it. 141 00:15:31,043 --> 00:15:33,083 The Salvadora tree 142 00:15:33,083 --> 00:15:35,123 is one of their favourites. 143 00:15:41,283 --> 00:15:43,323 These trees draw up cool water 144 00:15:43,323 --> 00:15:44,963 from deep below ground... 145 00:15:46,123 --> 00:15:49,403 ...so their trunks are a few degrees cooler 146 00:15:49,403 --> 00:15:51,243 than everything else around. 147 00:15:55,283 --> 00:15:57,363 At the hottest time of day, 148 00:15:57,363 --> 00:16:01,923 some embraces can last for over four hours. 149 00:16:05,603 --> 00:16:07,963 And some trees are so popular... 150 00:16:09,163 --> 00:16:11,403 ...there isn't an inch to spare. 151 00:16:17,083 --> 00:16:19,083 This remarkable behaviour 152 00:16:19,083 --> 00:16:23,123 was first recorded by scientists in 2017. 153 00:16:39,163 --> 00:16:41,123 As the world becomes hotter, 154 00:16:41,123 --> 00:16:44,043 we may see cooling behaviours like this 155 00:16:44,043 --> 00:16:46,283 become more and more common. 156 00:16:56,083 --> 00:16:59,923 But some sifakas have gone one stage further. 157 00:17:06,803 --> 00:17:09,043 They know the best place 158 00:17:09,043 --> 00:17:10,563 is within the trunk 159 00:17:10,563 --> 00:17:12,523 of the Salvadora tree. 160 00:17:19,803 --> 00:17:22,683 Here, the temperature can be even cooler. 161 00:17:29,003 --> 00:17:31,443 And that can give real respite 162 00:17:31,443 --> 00:17:33,683 from the oven outside. 163 00:17:43,323 --> 00:17:46,083 Sifakas have learnt that tree-hugging 164 00:17:46,083 --> 00:17:49,163 is an effective way to keep cool. 165 00:17:53,043 --> 00:17:54,283 But some mammals 166 00:17:54,283 --> 00:17:58,203 face a far more dangerous source of heat than the sun. 167 00:18:03,043 --> 00:18:06,443 The dry eucalyptus forests of Australia. 168 00:18:08,363 --> 00:18:12,363 Home to one of the most bizarre of all mammals. 169 00:18:16,883 --> 00:18:18,443 An echidna. 170 00:18:22,363 --> 00:18:24,683 It's one of the most ancient of mammals 171 00:18:24,683 --> 00:18:26,563 and reproduces 172 00:18:26,563 --> 00:18:28,283 by laying eggs. 173 00:18:36,043 --> 00:18:37,523 She's out foraging, 174 00:18:37,523 --> 00:18:40,083 using her highly sensitive nose 175 00:18:40,083 --> 00:18:42,403 to look for ants and termites. 176 00:18:55,243 --> 00:18:57,083 To work at its best, 177 00:18:57,083 --> 00:18:59,283 her nose has to be kept moist. 178 00:18:59,283 --> 00:19:00,643 And this has led her 179 00:19:00,643 --> 00:19:03,803 to developing an unusual skill. 180 00:19:05,803 --> 00:19:08,283 She blows snot bubbles. 181 00:19:09,803 --> 00:19:11,803 As the moisture evaporates, 182 00:19:11,803 --> 00:19:13,803 it helps to cool her down. 183 00:19:21,163 --> 00:19:24,043 But this female is not alone. 184 00:19:37,403 --> 00:19:39,043 She can be followed 185 00:19:39,043 --> 00:19:41,683 by up to ten or more males... 186 00:19:45,043 --> 00:19:47,523 ...all vying for her attention. 187 00:19:50,363 --> 00:19:51,763 It's what is known 188 00:19:51,763 --> 00:19:54,043 as a love train. 189 00:20:05,443 --> 00:20:08,083 And it can run for weeks. 190 00:20:14,363 --> 00:20:17,563 One male has managed to get close. 191 00:20:19,363 --> 00:20:22,043 With such a prickly partner, 192 00:20:22,043 --> 00:20:24,563 a gentle touch is needed. 193 00:20:27,483 --> 00:20:29,763 But some romantic liaisons 194 00:20:29,763 --> 00:20:32,123 don't last long. 195 00:20:32,123 --> 00:20:34,323 With their sensitive noses, 196 00:20:34,323 --> 00:20:36,563 echidnas can detect 197 00:20:36,563 --> 00:20:38,923 the early signs of danger. 198 00:20:45,163 --> 00:20:46,643 A bushfire. 199 00:20:51,963 --> 00:20:53,443 Their best chance of safety 200 00:20:53,443 --> 00:20:55,603 {\an8}is to get underground. 201 00:21:03,403 --> 00:21:05,643 Echidnas often go underground 202 00:21:05,643 --> 00:21:08,403 to avoid the severe heat of the day. 203 00:21:12,043 --> 00:21:14,003 But they also have to do so 204 00:21:14,003 --> 00:21:16,083 to escape the heat of a bushfire. 205 00:21:25,763 --> 00:21:28,763 Between 2019 and 2020, 206 00:21:28,763 --> 00:21:30,123 Australia experienced 207 00:21:30,123 --> 00:21:33,843 its most catastrophic bushfire season on record. 208 00:21:43,803 --> 00:21:46,763 Over 100,000 square miles, 209 00:21:46,763 --> 00:21:49,723 an area larger than the United Kingdom, 210 00:21:49,723 --> 00:21:51,203 was devastated. 211 00:21:54,843 --> 00:21:57,803 But in such dangerous conditions, 212 00:21:57,803 --> 00:22:01,443 echidna have a remarkable survival skill. 213 00:22:04,483 --> 00:22:06,643 They go into a deep sleep 214 00:22:06,643 --> 00:22:09,043 known as a torpor. 215 00:22:11,723 --> 00:22:13,843 It's a form of hibernation, 216 00:22:13,843 --> 00:22:15,843 during which their heart rate 217 00:22:15,843 --> 00:22:18,443 may slow to only four beats a minute. 218 00:22:20,603 --> 00:22:23,083 Their core body temperature drops. 219 00:22:25,283 --> 00:22:27,683 And they may only take a breath 220 00:22:27,683 --> 00:22:29,723 once every three minutes. 221 00:22:32,203 --> 00:22:33,403 By doing this, 222 00:22:33,403 --> 00:22:37,523 they can live for days without food or water. 223 00:22:54,843 --> 00:22:57,323 After the fire has passed... 224 00:23:01,683 --> 00:23:05,323 ...the echidnas begin to emerge. 225 00:23:13,963 --> 00:23:16,603 Not all are unscathed. 226 00:23:19,043 --> 00:23:20,563 Melted spines 227 00:23:20,563 --> 00:23:22,043 show that this one 228 00:23:22,043 --> 00:23:23,923 has had a close call. 229 00:23:32,723 --> 00:23:33,843 But others 230 00:23:33,843 --> 00:23:35,843 show no ill effects. 231 00:23:38,763 --> 00:23:40,643 Their unique adaptations 232 00:23:40,643 --> 00:23:42,123 have kept them safe. 233 00:23:45,363 --> 00:23:49,163 But as global temperatures rise, 234 00:23:49,163 --> 00:23:52,003 forest fires are becoming more intense... 235 00:23:53,123 --> 00:23:54,603 ...and more frequent. 236 00:23:57,563 --> 00:24:00,683 The survival skills of echidnas 237 00:24:00,683 --> 00:24:02,883 will become even more crucial. 238 00:24:11,243 --> 00:24:13,603 Going underground to avoid the heat 239 00:24:13,603 --> 00:24:15,643 makes obvious sense, 240 00:24:15,643 --> 00:24:16,843 but one mammal 241 00:24:16,843 --> 00:24:19,603 does the exact opposite. 242 00:24:22,883 --> 00:24:25,523 Harris's antelope squirrel. 243 00:24:31,083 --> 00:24:33,203 Even during the height of summer, 244 00:24:33,203 --> 00:24:34,683 when ground temperatures 245 00:24:34,683 --> 00:24:37,363 can exceed 80 degrees Celsius... 246 00:24:38,563 --> 00:24:40,363 ...he will be out foraging 247 00:24:40,363 --> 00:24:43,523 amongst the cactus of the Arizona desert. 248 00:24:48,563 --> 00:24:50,363 By being out now, 249 00:24:50,363 --> 00:24:53,723 he avoids competition from other mammals. 250 00:24:53,723 --> 00:24:57,443 But the squirrels don't have it all their own way. 251 00:25:02,483 --> 00:25:04,323 A rattlesnake, 252 00:25:04,323 --> 00:25:05,883 which is looking for 253 00:25:05,883 --> 00:25:07,643 a rodent-sized meal. 254 00:25:17,443 --> 00:25:19,403 It's a stand-off... 255 00:25:20,843 --> 00:25:22,723 ...to see who can withstand 256 00:25:22,723 --> 00:25:24,203 the most heat. 257 00:25:29,203 --> 00:25:32,003 As the ground temperature continues to rise, 258 00:25:32,003 --> 00:25:34,203 the squirrel's core temperature 259 00:25:34,203 --> 00:25:36,723 reaches 43 degrees Celsius. 260 00:25:40,003 --> 00:25:42,363 That would be fatal for humans 261 00:25:42,363 --> 00:25:44,443 and most other animals. 262 00:25:47,523 --> 00:25:49,723 But the squirrels have a clever trick 263 00:25:49,723 --> 00:25:52,803 that can quickly reduce their body temperature. 264 00:25:56,963 --> 00:25:59,123 He heat-dumps. 265 00:26:01,763 --> 00:26:03,323 By spreading its hot body 266 00:26:03,323 --> 00:26:05,963 against the cooler sand in the shade, 267 00:26:05,963 --> 00:26:08,123 a squirrel can rapidly reduce 268 00:26:08,123 --> 00:26:10,043 its body temperature down 269 00:26:10,043 --> 00:26:12,843 by up to one degree a minute. 270 00:26:18,363 --> 00:26:21,003 The rattlesnake simply can't compete. 271 00:26:23,523 --> 00:26:25,683 It has to find shelter 272 00:26:25,683 --> 00:26:27,323 to avoid overheating. 273 00:26:34,003 --> 00:26:35,683 With the coast now clear, 274 00:26:35,683 --> 00:26:38,363 the squirrel can continue his search 275 00:26:38,363 --> 00:26:41,483 {\an8}for the fruit of the spiny cholla cactus. 276 00:26:48,323 --> 00:26:49,803 But this one 277 00:26:49,803 --> 00:26:53,243 has already lost all of its low-hanging fruit. 278 00:26:55,203 --> 00:26:56,923 There's only one thing for it. 279 00:27:00,683 --> 00:27:02,283 He will have to clamber up 280 00:27:02,283 --> 00:27:04,803 the spine-covered branches. 281 00:27:09,323 --> 00:27:11,403 He must be very cautious. 282 00:27:24,163 --> 00:27:25,723 But this fruit... 283 00:27:25,723 --> 00:27:27,443 ...is a stretch... 284 00:27:27,443 --> 00:27:29,483 ...too... far. 285 00:27:32,923 --> 00:27:34,243 Try again. 286 00:28:00,003 --> 00:28:02,083 But the price of success 287 00:28:02,083 --> 00:28:03,443 can be painful. 288 00:28:05,963 --> 00:28:07,003 He has to remove 289 00:28:07,003 --> 00:28:09,483 some very sharp spines. 290 00:28:18,923 --> 00:28:21,803 A final heat-dump 291 00:28:21,803 --> 00:28:24,523 before enjoying the fruit 292 00:28:24,523 --> 00:28:25,963 of his labour. 293 00:28:30,363 --> 00:28:31,923 This tiny squirrel 294 00:28:31,923 --> 00:28:35,443 has found a clever way to deal with the heat. 295 00:28:40,083 --> 00:28:42,443 But when you're nearly six metres tall 296 00:28:42,443 --> 00:28:44,563 and weigh almost two tonnes... 297 00:28:45,883 --> 00:28:48,843 ...it's altogether a much bigger problem. 298 00:28:58,323 --> 00:28:59,803 The Hoanib Valley 299 00:28:59,803 --> 00:29:02,283 on Namibia's Skeleton Coast. 300 00:29:08,203 --> 00:29:11,803 Home to some of nature's real giants. 301 00:29:16,923 --> 00:29:18,203 Giraffes. 302 00:29:25,643 --> 00:29:29,243 This herd is guarded by a dominant bull. 303 00:29:47,403 --> 00:29:50,163 They spend much of their day out in the open, 304 00:29:50,163 --> 00:29:51,643 searching for food. 305 00:29:54,283 --> 00:29:56,163 Their tongues are black 306 00:29:56,163 --> 00:29:59,483 with a pigment that acts as a sunblock. 307 00:30:08,563 --> 00:30:10,923 But this is only one of the ways 308 00:30:10,923 --> 00:30:13,523 by which a giraffe beats the heat. 309 00:30:24,203 --> 00:30:25,643 It's now about to use 310 00:30:25,643 --> 00:30:29,203 another of its heat-beating adaptations. 311 00:30:34,243 --> 00:30:35,883 A rival male. 312 00:30:42,763 --> 00:30:44,723 He approaches the females. 313 00:30:49,843 --> 00:30:52,723 The dominant bull moves to intercept. 314 00:31:01,723 --> 00:31:03,603 The bulls square up. 315 00:31:17,243 --> 00:31:19,523 These blows are violent enough 316 00:31:19,523 --> 00:31:22,203 to tear skin and break bone. 317 00:31:31,043 --> 00:31:33,723 They're now pushing themselves to the limit. 318 00:31:34,883 --> 00:31:36,363 Their core temperatures 319 00:31:36,363 --> 00:31:39,283 are rising to near-lethal levels. 320 00:31:41,163 --> 00:31:43,243 The reason they don't overheat 321 00:31:43,243 --> 00:31:46,363 is connected to their distinctive skin pattern. 322 00:31:48,563 --> 00:31:50,083 A thermal camera reveals 323 00:31:50,083 --> 00:31:52,483 that below each brown spot 324 00:31:52,483 --> 00:31:55,243 there is a dense network of blood vessels. 325 00:31:59,923 --> 00:32:02,683 As the giraffes' body temperatures rise... 326 00:32:04,083 --> 00:32:06,083 ...these blood vessels expand... 327 00:32:07,523 --> 00:32:09,243 ...releasing body heat... 328 00:32:10,203 --> 00:32:12,563 ...so enabling them to fight on. 329 00:32:17,443 --> 00:32:18,683 The force of each blow 330 00:32:18,683 --> 00:32:21,403 is visible as a white-hot slash. 331 00:32:41,843 --> 00:32:43,723 The dominant bull wins... 332 00:32:45,243 --> 00:32:47,163 ...and his rival retreats. 333 00:32:59,643 --> 00:33:02,603 In Trinidad lives a mammal 334 00:33:02,603 --> 00:33:05,563 that detects the heat that animals produce... 335 00:33:06,883 --> 00:33:09,003 ...and uses it to guide them 336 00:33:09,003 --> 00:33:11,763 to a drink of their victim's blood. 337 00:33:27,963 --> 00:33:31,243 The white-winged vampire bat. 338 00:33:34,763 --> 00:33:36,043 On the prowl 339 00:33:36,043 --> 00:33:37,683 for its next victim. 340 00:33:59,523 --> 00:34:02,163 This cockerel is fast asleep. 341 00:34:12,163 --> 00:34:13,763 But the bat must be careful. 342 00:34:15,283 --> 00:34:17,123 Cockerels are light sleepers. 343 00:34:24,003 --> 00:34:26,043 The bite must be delivered 344 00:34:26,043 --> 00:34:27,483 with precision. 345 00:34:33,723 --> 00:34:35,563 Heat-sensitive receptors 346 00:34:35,563 --> 00:34:37,203 enable vampire bats 347 00:34:37,203 --> 00:34:39,123 to detect subtle differences 348 00:34:39,123 --> 00:34:40,523 in temperature... 349 00:34:43,283 --> 00:34:45,643 ...so it can pinpoint exactly 350 00:34:45,643 --> 00:34:48,563 where the warm blood flows close to the skin. 351 00:34:58,923 --> 00:35:00,083 She bites. 352 00:35:07,323 --> 00:35:11,523 Her saliva contains a powerful anticoagulant 353 00:35:11,523 --> 00:35:13,443 known as draculin. 354 00:35:14,443 --> 00:35:16,483 It ensures that the blood 355 00:35:16,483 --> 00:35:18,763 continues to flow freely. 356 00:35:20,483 --> 00:35:22,563 This helps her feed quickly 357 00:35:22,563 --> 00:35:24,683 and avoids her being noticed. 358 00:35:33,083 --> 00:35:36,043 But blood isn't, in fact, very nutritious, 359 00:35:36,043 --> 00:35:37,523 so the bats have to drink 360 00:35:37,523 --> 00:35:39,443 over half their own body weight 361 00:35:39,443 --> 00:35:41,163 in one sitting. 362 00:35:42,923 --> 00:35:44,003 As a result, 363 00:35:44,003 --> 00:35:46,483 flight becomes nearly impossible. 364 00:35:50,163 --> 00:35:52,083 But her kidneys are remarkable... 365 00:35:54,203 --> 00:35:57,123 ...and quickly extract the water from her meal. 366 00:36:00,043 --> 00:36:01,883 So, within minutes, 367 00:36:01,883 --> 00:36:04,403 she vanishes into the darkness... 368 00:36:05,643 --> 00:36:09,203 ...leaving the cockerel none the wiser. 369 00:36:16,403 --> 00:36:18,043 While vampire bats use heat 370 00:36:18,043 --> 00:36:21,403 from the blood of their victims to find their meals, 371 00:36:21,403 --> 00:36:24,803 one mammal uses the heat from the sun. 372 00:36:26,603 --> 00:36:29,003 Uganda, in Africa, 373 00:36:29,003 --> 00:36:30,923 on the banks of the River Nile. 374 00:36:33,763 --> 00:36:36,003 A troop of baboons has gathered 375 00:36:36,003 --> 00:36:39,003 at the end of the long, hot dry season. 376 00:36:41,843 --> 00:36:42,923 They are waiting 377 00:36:42,923 --> 00:36:45,683 for a very special seasonal opportunity. 378 00:36:47,843 --> 00:36:49,243 It begins 379 00:36:49,243 --> 00:36:51,963 {\an8}with the annual emergence of flying termites. 380 00:36:58,043 --> 00:36:59,603 They provide the baboons 381 00:36:59,603 --> 00:37:02,443 with a small but much-needed treat. 382 00:37:12,283 --> 00:37:14,243 But the older members of the troop 383 00:37:14,243 --> 00:37:17,763 know there is another delicacy to be found here... 384 00:37:23,043 --> 00:37:24,643 ...one that provides them 385 00:37:24,643 --> 00:37:27,043 with a far more nourishing meal. 386 00:37:33,043 --> 00:37:34,723 A Nile crocodile. 387 00:37:40,483 --> 00:37:42,003 She laid her eggs... 388 00:37:43,443 --> 00:37:45,083 ...in the warm sand. 389 00:37:47,683 --> 00:37:51,283 The baboons would steal them if they could. 390 00:37:55,523 --> 00:37:57,523 But the crocodile, 391 00:37:57,523 --> 00:38:00,003 weighing nearly a quarter of a ton, 392 00:38:00,003 --> 00:38:03,443 is one of Africa's most formidable predators 393 00:38:03,443 --> 00:38:06,403 and well able to kill a baboon... 394 00:38:10,443 --> 00:38:13,763 ...so the utmost caution is required. 395 00:38:17,363 --> 00:38:19,123 Their plan is simple. 396 00:38:24,243 --> 00:38:25,643 They wait. 397 00:38:29,803 --> 00:38:32,283 Whilst the crocodile must stay in the sun, 398 00:38:32,283 --> 00:38:33,963 guarding its nest... 399 00:38:35,843 --> 00:38:39,043 ...the baboons keep their cool in the shade... 400 00:38:40,723 --> 00:38:43,323 ...waiting for just the right moment. 401 00:38:50,683 --> 00:38:53,123 The crocodile begins to gape. 402 00:38:58,843 --> 00:39:01,363 It's a way of losing heat. 403 00:39:05,803 --> 00:39:07,603 The sun 404 00:39:07,603 --> 00:39:09,003 gets stronger. 405 00:39:12,483 --> 00:39:15,043 But the crocodile stays on guard 406 00:39:15,043 --> 00:39:17,043 and risks overheating. 407 00:39:29,403 --> 00:39:31,763 Eventually, it gets so hot... 408 00:39:33,243 --> 00:39:35,643 ...that it takes to the water to cool down. 409 00:39:47,883 --> 00:39:51,203 But the baboons still do... 410 00:39:51,203 --> 00:39:52,643 ...nothing. 411 00:39:55,443 --> 00:39:58,443 Their waiting game has not yet finished. 412 00:40:02,363 --> 00:40:03,683 {\an8}There's no sense 413 00:40:03,683 --> 00:40:06,083 {\an8}in overexerting yourself in the heat... 414 00:40:07,603 --> 00:40:10,323 {\an8}...when you can let hungry monitor lizards 415 00:40:10,323 --> 00:40:11,883 {\an8}do the hard work. 416 00:40:35,003 --> 00:40:36,203 Finally, 417 00:40:36,203 --> 00:40:38,923 the moment they have been waiting for. 418 00:40:43,563 --> 00:40:46,283 Now they need to move fast. 419 00:40:46,283 --> 00:40:48,803 The crocodile won't be away for long. 420 00:41:11,003 --> 00:41:12,683 The oppressive heat 421 00:41:12,683 --> 00:41:16,083 has allowed the baboons to get the food they want. 422 00:41:23,763 --> 00:41:26,043 But there are few places in Africa 423 00:41:26,043 --> 00:41:27,843 where the battle to find food 424 00:41:27,843 --> 00:41:29,523 is more demanding 425 00:41:29,523 --> 00:41:32,683 than the Etosha salt pan in Namibia. 426 00:41:40,603 --> 00:41:44,283 As temperatures rise across this vast wilderness, 427 00:41:44,283 --> 00:41:46,083 mammals of many kinds 428 00:41:46,083 --> 00:41:49,203 are gathering around a shrinking water hole. 429 00:41:59,523 --> 00:42:01,243 For a female jackal... 430 00:42:02,763 --> 00:42:05,083 ...this is a good place to hunt. 431 00:42:08,803 --> 00:42:11,563 But it's almost too crowded. 432 00:42:16,163 --> 00:42:18,323 For a jackal to be successful, 433 00:42:18,323 --> 00:42:20,443 it needs to be clever. 434 00:42:22,123 --> 00:42:23,643 Just a ghost 435 00:42:23,643 --> 00:42:24,803 in the background. 436 00:42:31,763 --> 00:42:33,843 Some of the largest mammals on Earth 437 00:42:33,843 --> 00:42:35,763 dominate the water's edge. 438 00:42:44,723 --> 00:42:47,443 The jackal must bide her time. 439 00:43:01,963 --> 00:43:04,523 She spots possible prey. 440 00:43:10,243 --> 00:43:11,483 Guinea fowl. 441 00:43:48,843 --> 00:43:50,403 Thirst, however, 442 00:43:50,403 --> 00:43:52,283 dominates everything else. 443 00:43:53,963 --> 00:43:56,323 And hunters and hunted 444 00:43:56,323 --> 00:43:58,603 drink alongside one another. 445 00:44:04,763 --> 00:44:06,883 Temperatures are still rising. 446 00:44:10,803 --> 00:44:12,843 The drinkers start to quarrel... 447 00:44:20,283 --> 00:44:21,763 ...and she retreats. 448 00:44:27,363 --> 00:44:28,403 But then... 449 00:44:29,923 --> 00:44:32,723 ...things get even more difficult. 450 00:44:37,083 --> 00:44:38,643 A hyena. 451 00:44:44,603 --> 00:44:46,243 More than capable 452 00:44:46,243 --> 00:44:48,163 of killing a jackal. 453 00:44:56,643 --> 00:44:59,403 But driven by hunger and thirst... 454 00:45:04,403 --> 00:45:07,123 ...this female holds her ground... 455 00:45:18,683 --> 00:45:22,083 ...and now can get back to hunting. 456 00:45:26,283 --> 00:45:28,203 This time, she sets her sights 457 00:45:28,203 --> 00:45:29,803 on a flock of doves... 458 00:45:36,683 --> 00:45:39,923 ...and tries a more subtle approach. 459 00:45:43,643 --> 00:45:46,123 Hiding in plain sight. 460 00:45:50,523 --> 00:45:52,163 Lulling the birds 461 00:45:52,163 --> 00:45:55,003 into a false sense of security. 462 00:46:14,603 --> 00:46:17,243 She waits for the perfect moment. 463 00:46:27,003 --> 00:46:29,203 But they aren't so easily caught. 464 00:46:33,003 --> 00:46:34,163 Nonetheless... 465 00:46:35,403 --> 00:46:36,883 ...she's determined. 466 00:47:09,243 --> 00:47:11,443 Success at last. 467 00:47:16,763 --> 00:47:18,603 Her mate arrives... 468 00:47:20,043 --> 00:47:23,163 ...and he has brought their hungry pups with him. 469 00:47:30,683 --> 00:47:32,923 With so many mouths to feed... 470 00:47:34,163 --> 00:47:36,803 ...she will have to be hunting again soon. 471 00:47:43,843 --> 00:47:46,763 Mammals have an extraordinary ability 472 00:47:46,763 --> 00:47:48,083 to find water... 473 00:47:50,123 --> 00:47:51,523 ...stay cool... 474 00:47:53,083 --> 00:47:54,643 ...and use heat 475 00:47:54,643 --> 00:47:56,163 to their advantage. 476 00:47:57,643 --> 00:47:59,763 That has enabled them to flourish 477 00:47:59,763 --> 00:48:02,763 in some of the harshest and hottest environments 478 00:48:02,763 --> 00:48:04,243 on the planet. 479 00:48:10,123 --> 00:48:13,283 But if the world is indeed to become even hotter, 480 00:48:13,283 --> 00:48:14,643 as is predicted... 481 00:48:16,563 --> 00:48:19,403 ...then the challenges facing mammals 482 00:48:19,403 --> 00:48:22,763 will become greater than they have ever been. 483 00:48:38,083 --> 00:48:39,643 In Madagascar, 484 00:48:39,643 --> 00:48:41,803 the Mammals team hoped to be the first to film 485 00:48:41,803 --> 00:48:44,403 some recently discovered behaviour... 486 00:48:46,043 --> 00:48:48,883 ...sifaka lemurs tree-hugging. 487 00:48:50,283 --> 00:48:52,203 But to get there, 488 00:48:52,203 --> 00:48:54,963 it's a three-day drive over rough terrain. 489 00:48:57,123 --> 00:48:59,803 A little too much for producer Rob Pilley. 490 00:49:11,403 --> 00:49:13,643 Happy to be back on terra firma, 491 00:49:13,643 --> 00:49:15,443 the team set off on foot 492 00:49:15,443 --> 00:49:17,283 through the spiny forest. 493 00:49:18,723 --> 00:49:20,203 They've joined forces 494 00:49:20,203 --> 00:49:21,763 with local scientists 495 00:49:21,763 --> 00:49:23,763 from the ESSA research group. 496 00:49:25,283 --> 00:49:27,883 And thanks to their expertise, 497 00:49:27,883 --> 00:49:30,603 it doesn't take long to find the sifaka. 498 00:49:35,643 --> 00:49:37,403 They're a little wary of humans, 499 00:49:37,403 --> 00:49:40,123 so we have to go really slowly, approach them slowly. 500 00:49:40,123 --> 00:49:41,923 They're quite skittish. 501 00:49:44,443 --> 00:49:46,723 The sifaka are much more nimble 502 00:49:46,723 --> 00:49:48,403 moving through the forest 503 00:49:48,403 --> 00:49:51,323 than the crew carrying bulky kit. 504 00:49:52,403 --> 00:49:53,883 Keeping up with the troop 505 00:49:53,883 --> 00:49:56,243 is not without its snags. 506 00:49:56,243 --> 00:49:57,883 Ah, everything is out to get you, 507 00:49:57,883 --> 00:50:00,243 it's just this giant cactus forest. 508 00:50:00,243 --> 00:50:02,083 They are everywhere, the spines. 509 00:50:03,523 --> 00:50:05,083 And the dense scrub 510 00:50:05,083 --> 00:50:07,523 makes getting any shots a challenge. 511 00:50:09,043 --> 00:50:12,363 Yeah, it kind of makes you almost forced to shoot 512 00:50:12,363 --> 00:50:15,003 such high-angle shots when it's so dense 513 00:50:15,003 --> 00:50:16,723 cos we can't get further back. 514 00:50:16,723 --> 00:50:18,643 Also just manoeuvring around the forest, 515 00:50:18,643 --> 00:50:20,243 it's pretty hectic. 516 00:50:20,243 --> 00:50:22,563 Trying to go quietly without snagging your camera 517 00:50:22,563 --> 00:50:24,763 or your lens or a cable or... 518 00:50:24,763 --> 00:50:26,763 ...is, uh, not easy. 519 00:50:28,483 --> 00:50:30,163 Over the following days, 520 00:50:30,163 --> 00:50:33,123 the team struggle through the heat, 521 00:50:33,123 --> 00:50:36,203 with the lemurs giving them the run-around. 522 00:50:36,203 --> 00:50:39,763 We just found a group and they've just disappeared off. 523 00:50:39,763 --> 00:50:43,043 This is going to be a marathon, not a sprint. 524 00:50:43,043 --> 00:50:44,603 Lemurs Behaving Badly! 525 00:50:51,723 --> 00:50:54,083 As temperatures rise, 526 00:50:54,083 --> 00:50:56,283 the lemurs finally seem to settle. 527 00:51:02,443 --> 00:51:05,843 This could be a breakthrough for the team. 528 00:51:05,843 --> 00:51:08,363 Stu is up front. 529 00:51:08,363 --> 00:51:09,843 It's just possible 530 00:51:09,843 --> 00:51:11,043 that we have found 531 00:51:11,043 --> 00:51:13,763 the perfect tree-hugging group. 532 00:51:17,603 --> 00:51:18,803 Fingers crossed. 533 00:51:23,643 --> 00:51:25,003 Not this time. 534 00:51:26,323 --> 00:51:28,923 Just been given the run-around all morning by these lemurs - 535 00:51:28,923 --> 00:51:30,843 starburst, every direction. 536 00:51:30,843 --> 00:51:32,283 Couldn't get a single shot. 537 00:51:32,283 --> 00:51:34,363 It's like the worst day ever! 538 00:51:39,403 --> 00:51:40,763 Back at camp, 539 00:51:40,763 --> 00:51:43,483 it's 45 degrees in the shade. 540 00:51:46,003 --> 00:51:49,203 While Stuart finds a way to cool himself off... 541 00:51:49,203 --> 00:51:50,643 Whew! That's good! 542 00:51:50,643 --> 00:51:53,883 ...Jeandre is more worried about the equipment. 543 00:51:53,883 --> 00:51:56,763 We raised the laptop up on these hard drives 544 00:51:56,763 --> 00:51:59,163 to give it some cooling. It's just too hot. 545 00:51:59,163 --> 00:52:00,603 The cameras are melting. 546 00:52:00,603 --> 00:52:02,083 The little metal pins in the camera 547 00:52:02,083 --> 00:52:03,923 have literally melted. It's... 548 00:52:03,923 --> 00:52:05,563 I've never had that on a shoot. 549 00:52:08,803 --> 00:52:10,043 Despite the heat, 550 00:52:10,043 --> 00:52:11,563 the team are forced to work 551 00:52:11,563 --> 00:52:13,403 during the hottest part of the day 552 00:52:13,403 --> 00:52:14,723 if they want to film 553 00:52:14,723 --> 00:52:17,123 this unique tree-hugging behaviour. 554 00:52:21,243 --> 00:52:24,243 But as the lemurs lead them deeper into the forest, 555 00:52:24,243 --> 00:52:26,763 they notice something is amiss. 556 00:52:28,083 --> 00:52:30,963 In the heart of this protected area, 557 00:52:30,963 --> 00:52:33,523 there are signs that trees have been felled. 558 00:52:37,043 --> 00:52:39,603 We see for the last two, three years 559 00:52:39,603 --> 00:52:42,003 increasing cutting within the forest 560 00:52:42,003 --> 00:52:43,803 and we believe that it's because 561 00:52:43,803 --> 00:52:46,243 these people are so desperate 562 00:52:46,243 --> 00:52:49,723 and cut the trees for the forage for their animals 563 00:52:49,723 --> 00:52:51,723 and then for their daily needs. 564 00:52:53,003 --> 00:52:54,763 With ongoing drought, 565 00:52:54,763 --> 00:52:56,403 crops are failing, 566 00:52:56,403 --> 00:52:58,443 and local people are forced 567 00:52:58,443 --> 00:53:01,163 to turn to the forest to make ends meet. 568 00:53:03,483 --> 00:53:05,283 Across Madagascar, 569 00:53:05,283 --> 00:53:08,043 deforestation and the effects of climate change 570 00:53:08,043 --> 00:53:10,083 are only making life harder 571 00:53:10,083 --> 00:53:12,283 for both wildlife and people. 572 00:53:13,763 --> 00:53:16,283 It's a sobering reminder to the team 573 00:53:16,283 --> 00:53:19,043 of the problems faced by these lemurs, 574 00:53:19,043 --> 00:53:22,923 who are having to adapt to a rapidly changing world. 575 00:53:25,323 --> 00:53:26,563 Back on the trail, 576 00:53:26,563 --> 00:53:29,683 the team split up to cover more ground. 577 00:53:32,563 --> 00:53:34,123 Now separated, 578 00:53:34,123 --> 00:53:36,803 the researchers have a special way to keep in touch. 579 00:53:44,603 --> 00:53:47,603 Using calls similar to the animals 580 00:53:47,603 --> 00:53:49,803 lets them maintain a low profile. 581 00:53:50,883 --> 00:53:53,323 But as they push forward, 582 00:53:53,323 --> 00:53:54,603 the heat of the day 583 00:53:54,603 --> 00:53:57,723 is taking its toll on Jeandre and Rob. 584 00:53:58,963 --> 00:54:01,043 We... we all just have to stop for a bit, 585 00:54:01,043 --> 00:54:02,483 have a breather. 586 00:54:06,123 --> 00:54:08,123 And when they start moving again, 587 00:54:08,123 --> 00:54:11,043 they quickly realise they're lost. 588 00:54:11,043 --> 00:54:12,443 It all looks the same. 589 00:54:16,043 --> 00:54:17,363 I think it's up here. 590 00:54:19,043 --> 00:54:20,843 We're not really quite sure... 591 00:54:22,923 --> 00:54:24,083 ...where we are. 592 00:54:39,643 --> 00:54:40,883 Ow! 593 00:54:46,803 --> 00:54:48,083 In these conditions, 594 00:54:48,083 --> 00:54:50,923 it only takes a few hours for heatstroke to set in. 595 00:55:02,723 --> 00:55:04,883 Yeah, OK, they're ahead, they're ahead. That's good. 596 00:55:05,843 --> 00:55:07,443 There's a friendly face! 597 00:55:09,643 --> 00:55:11,363 So nice to see you. 598 00:55:11,363 --> 00:55:13,323 Somebody wandered off that way... 599 00:55:13,323 --> 00:55:15,123 Quickly, things can go really pear-shaped 600 00:55:15,123 --> 00:55:17,563 unless you're on your game, so... 601 00:55:17,563 --> 00:55:19,203 A lesson learned, definitely. 602 00:55:21,563 --> 00:55:23,403 Despite this close call, 603 00:55:23,403 --> 00:55:25,603 the team are determined to continue. 604 00:55:29,163 --> 00:55:31,003 It's the hottest day so far, 605 00:55:31,003 --> 00:55:33,083 which should work in their favour. 606 00:55:43,563 --> 00:55:44,883 At last, 607 00:55:44,883 --> 00:55:47,243 they find a group that is settling. 608 00:55:56,483 --> 00:56:00,483 Lemurs only tree-hug in the hottest conditions. 609 00:56:02,043 --> 00:56:05,163 All the crew can do now is wait. 610 00:56:42,203 --> 00:56:43,243 Finally... 611 00:56:45,363 --> 00:56:46,603 ...what they came for. 612 00:57:00,203 --> 00:57:03,883 Thanks to the work of this research team, 613 00:57:03,883 --> 00:57:08,083 {\an8}the efforts to protect the sifakas' home 614 00:57:08,083 --> 00:57:09,123 will continue. 615 00:57:10,163 --> 00:57:12,043 With the education 616 00:57:12,043 --> 00:57:15,043 and working together at different levels, 617 00:57:15,043 --> 00:57:17,363 from locals to national, 618 00:57:17,363 --> 00:57:18,883 to international levels, 619 00:57:18,883 --> 00:57:20,963 for common goals, 620 00:57:20,963 --> 00:57:25,163 then I be very optimistic, the future of Madagascar. 621 00:57:29,963 --> 00:57:32,123 Next time... 622 00:57:32,123 --> 00:57:34,123 ...forests, where we 623 00:57:34,123 --> 00:57:39,003 discover how nearly three quarters of all mammal species 624 00:57:39,003 --> 00:57:43,203 have made their home in this, 625 00:57:43,203 --> 00:57:47,403 the richest and most diverse habitat... 626 00:57:49,083 --> 00:57:50,683 ...on Earth.