1 00:00:00,410 --> 00:00:01,610 [WHIMPERING, SNARLING] 2 00:00:01,770 --> 00:00:06,850 Previously, we've witnessed how animals survive Yellowstone's Extremes. 3 00:00:09,410 --> 00:00:12,610 Starting in winter, it was well below freezing 4 00:00:12,690 --> 00:00:15,330 and some animals really struggled. 5 00:00:18,290 --> 00:00:24,090 Then in spring, temperatures jumped nearly 30 degrees in a fortnight. 6 00:00:24,450 --> 00:00:28,810 And wildlife had to cope with the thaw coming three weeks early. 7 00:00:29,650 --> 00:00:33,730 Now, summer is here, and there are new challenges. 8 00:00:34,610 --> 00:00:39,730 The melt water will dry out fast, food becomes scarce, 9 00:00:41,090 --> 00:00:42,650 and if there's no rain, 10 00:00:42,730 --> 00:00:47,410 wildfires will threaten to destroy the habitats animals rely on. 11 00:00:49,490 --> 00:00:50,490 [SQUEAKS] 12 00:00:51,730 --> 00:00:55,130 Welcome to Yellowstone's blazing summer. 13 00:01:12,570 --> 00:01:15,530 So far, in 2016, 14 00:01:15,610 --> 00:01:19,610 every month has been hotter than average in Greater Yellowstone. 15 00:01:21,330 --> 00:01:25,890 If the trend continues, summer could reach record temperatures, 16 00:01:25,970 --> 00:01:29,210 and push animals to the brink of survival. 17 00:01:34,210 --> 00:01:38,090 Yellowstone lies over 600 miles from the Pacific, 18 00:01:38,170 --> 00:01:40,330 and has a continental climate, 19 00:01:40,450 --> 00:01:43,570 which means summers can be relentlessly hot. 20 00:01:47,530 --> 00:01:51,090 Now, at the moment, it's all still looking quiet lash and green, 21 00:01:51,170 --> 00:01:54,650 but in the coming weeks as the temperatures continue to rise, 22 00:01:54,730 --> 00:01:58,610 the vegetation will start to wither, valleys will become dust bowls, 23 00:01:58,730 --> 00:02:01,450 and lakes and streams will start to dry up. 24 00:02:06,130 --> 00:02:09,490 Wildlife must travel further in search of food, 25 00:02:09,650 --> 00:02:12,450 drinking water, and shelter from the heat. 26 00:02:14,570 --> 00:02:16,570 ARYEE: Young animals born back in spring, 27 00:02:16,650 --> 00:02:19,210 are now entering their first summer. 28 00:02:19,290 --> 00:02:22,490 They are lot more mobile, but still need to avoid danger 29 00:02:22,570 --> 00:02:24,530 whilst exploring on those unsteady lakes. 30 00:02:30,690 --> 00:02:33,970 HUMBLE: For this latest generation, the changing climate 31 00:02:34,050 --> 00:02:37,010 will make their lives even more challenging. 32 00:02:40,890 --> 00:02:42,130 In spring, 33 00:02:42,210 --> 00:02:46,450 the beaver family was affected by the unusually warm temperatures. 34 00:02:49,130 --> 00:02:52,770 Huge volumes of melt water flooded into the Snake river 35 00:02:52,850 --> 00:02:57,210 where the beavers had made their home in the south of Greater Yellowstone. 36 00:02:57,930 --> 00:03:01,690 Snow melting from the all the way up there in the Teton mountains, 37 00:03:01,770 --> 00:03:03,730 rushed down in a deluge, 38 00:03:03,810 --> 00:03:06,410 and threatened to wash our beaver dam away. 39 00:03:08,210 --> 00:03:11,650 Beavers dam rivers to create a series of ponds 40 00:03:11,730 --> 00:03:15,370 where they live and feed, safe from predators. 41 00:03:15,450 --> 00:03:19,290 After working flat out on emergency repairs to the dam, 42 00:03:19,370 --> 00:03:22,210 the beavers just managed to save their home from the flood. 43 00:03:26,330 --> 00:03:30,090 Now in summer, the family could face the opposite challenge, 44 00:03:30,170 --> 00:03:32,090 too little water in the river. 45 00:03:34,290 --> 00:03:37,570 I've come to meet wildlife cameraman, Jeff Hogan, 46 00:03:37,650 --> 00:03:39,450 who's been following the beavers. 47 00:03:40,970 --> 00:03:41,970 ARYEE: Hey, Jeff. 48 00:03:42,570 --> 00:03:43,770 HOGAN: Hey. ARYEE: How's it going? 49 00:03:43,850 --> 00:03:45,130 Hey, there you are. How you doing? 50 00:03:46,650 --> 00:03:49,210 ARYEE: Jeff was filming great grey owls in spring. 51 00:03:49,610 --> 00:03:54,130 Now, he'll use his specialist skills to study the beavers, 52 00:03:54,250 --> 00:03:58,650 and has installed an infrared camera inside their lodge. 53 00:03:59,890 --> 00:04:01,250 [SQUEAKS] 54 00:04:04,130 --> 00:04:06,930 I got something to show you. There's a bit of a surprise. 55 00:04:09,730 --> 00:04:14,290 ARYEE: This footage looks like the male and female I saw here in spring. 56 00:04:14,930 --> 00:04:16,690 See, it's a couple of big fat beavers... 57 00:04:16,770 --> 00:04:17,770 Yeah. 58 00:04:22,050 --> 00:04:25,290 ARYEE: But then, something unexpected. 59 00:04:31,170 --> 00:04:35,290 Oh! Oh, my gosh! [LAUGHS] 60 00:04:36,010 --> 00:04:38,970 ARYEE: That's so adorable. HOGAN: That's a great shot. 61 00:04:41,290 --> 00:04:44,130 -Oh, my goodness. No way. -That's amazing. 62 00:04:46,090 --> 00:04:49,210 ARYEE: Oh, man, they're so adorable. 63 00:04:54,730 --> 00:05:00,050 ARYEE: Baby beavers are called kits, and mum has given birth to three. 64 00:05:01,050 --> 00:05:04,730 HOGAN: I would say they're probably about ten weeks of age maybe. 65 00:05:07,010 --> 00:05:09,210 ARYEE: Kits are precocial, 66 00:05:09,290 --> 00:05:12,930 which means they're mobile and quite advanced from birth, 67 00:05:13,010 --> 00:05:17,930 emerging with a full coat of thick fur, sharp, chisel-like teeth, 68 00:05:20,010 --> 00:05:22,290 and the characteristic flat tail. 69 00:05:25,050 --> 00:05:28,290 This they use as a rudder to steer when swimming, 70 00:05:28,450 --> 00:05:31,690 which they can do within a day of being born. 71 00:05:32,770 --> 00:05:35,690 But these three still rely on their family, 72 00:05:35,770 --> 00:05:38,130 to bring them food from outside the lodge. 73 00:05:40,370 --> 00:05:41,690 HOGAN: I got another clip for you. 74 00:05:47,330 --> 00:05:50,010 ARYEE: Oh, look at all that willow. 75 00:05:50,090 --> 00:05:55,010 This adult beaver just brought in three or four branches, all bundled up. 76 00:05:57,730 --> 00:06:01,930 And that little young ones will just jump on this. 77 00:06:03,090 --> 00:06:04,770 They'll gobble out right down. 78 00:06:13,890 --> 00:06:15,170 ARYEE: At ten weeks old, 79 00:06:15,250 --> 00:06:17,770 these kits has stopped drinking their mother's milk. 80 00:06:18,410 --> 00:06:20,850 They now have an adult diet. 81 00:06:25,890 --> 00:06:31,170 In summer, the ponds that beavers create become their vegetable gardens. 82 00:06:31,250 --> 00:06:34,770 The slow warm waters create optimal conditions 83 00:06:34,850 --> 00:06:36,530 for edible plants to grow. 84 00:06:42,850 --> 00:06:47,290 Mum, dad and last year's young are working overtime 85 00:06:47,370 --> 00:06:50,890 collecting food for the kits, and keeping the moat to clean 86 00:06:50,970 --> 00:06:52,610 by washing grassy bedding. 87 00:07:06,890 --> 00:07:09,730 In a matter of days, the kits will leave the lodge 88 00:07:09,890 --> 00:07:14,250 and learn to forage for their own food whilst avoiding predators. 89 00:07:16,490 --> 00:07:21,410 Around 50% of beaver kits don't survive their first six months. 90 00:07:21,490 --> 00:07:23,530 It's a critical time for this family. 91 00:07:23,810 --> 00:07:27,170 And Jeff will be following them every step of the way. 92 00:07:32,050 --> 00:07:36,450 HUMBLE: Across Yellowstone, our teams have been documenting signs 93 00:07:36,530 --> 00:07:41,050 that an early spring thaw kick-started an early summer. 94 00:07:42,410 --> 00:07:46,490 As icy melt waters flowing of the mountains subsided, 95 00:07:46,930 --> 00:07:49,730 streams warmed rapidly in the sun. 96 00:07:51,530 --> 00:07:55,730 And the surface of the water started to dance. 97 00:08:02,530 --> 00:08:08,050 Rising water temperatures trigger mayflies to hatch in their millions. 98 00:08:21,090 --> 00:08:25,810 These conditions are the starting pistol for an important event. 99 00:08:29,650 --> 00:08:32,370 The arrival of cut-throat trout. 100 00:08:34,770 --> 00:08:38,770 Many have spent the winter in Yellowstone's deep rivers and lakes, 101 00:08:38,890 --> 00:08:44,970 but migrate upstream to feed on mayflies and spawn in these shallow waters. 102 00:08:49,210 --> 00:08:52,970 Every year, the arrival of this protein rich fish 103 00:08:53,050 --> 00:08:56,370 creates a feeding bonanza for river otters, 104 00:08:56,450 --> 00:09:01,850 mink, bears, and birds of prey, like eagles and osprey, 105 00:09:03,410 --> 00:09:07,330 over 20 different species of birds and mammals. 106 00:09:10,970 --> 00:09:14,250 This year, the early snow melt have given these predators 107 00:09:14,330 --> 00:09:16,570 a head start to flatten up. 108 00:09:21,930 --> 00:09:23,890 ARYEE: While summer temperatures have created 109 00:09:23,970 --> 00:09:25,970 a frenzy of activity on the rivers, 110 00:09:26,570 --> 00:09:30,610 Yellowstone's low altitude grasslands are eerily quiet. 111 00:09:32,650 --> 00:09:36,610 In spring, herds of elk and bison were feeding here. 112 00:09:36,690 --> 00:09:38,290 But they've moved on, 113 00:09:38,370 --> 00:09:41,010 as the green vegetation withers in the heat. 114 00:09:42,450 --> 00:09:45,890 What the locals call "The brown up has begun." 115 00:09:48,610 --> 00:09:52,170 Over the course of just a few months, this ground has gone from being covered 116 00:09:52,250 --> 00:09:57,050 in feet of snow to lush grass, which is now scorched, died away, 117 00:09:57,130 --> 00:09:59,450 and has a very little nutrition. 118 00:09:59,650 --> 00:10:03,530 So grazing animals like bison and elk need to move further up the mountains, 119 00:10:03,610 --> 00:10:05,170 in search of green shoots. 120 00:10:07,970 --> 00:10:11,530 ARYEE: As the summer continues, the brown up will creep higher. 121 00:10:14,570 --> 00:10:17,130 Bison and elk must keep moving. 122 00:10:23,010 --> 00:10:26,970 By July, bison have arrived at summer grazing grounds 123 00:10:27,050 --> 00:10:29,130 on Yellowstone's high plateau. 124 00:10:32,650 --> 00:10:37,050 This is the only time mature males and females come together, 125 00:10:37,130 --> 00:10:40,490 and herds can reach a thousand strong. 126 00:10:41,250 --> 00:10:45,690 Scientist think this summer, the bison will look particularly impressive, 127 00:10:45,770 --> 00:10:48,570 after an abundance of grazing during the warm spring. 128 00:10:49,290 --> 00:10:52,570 So Kate's gone to check out what kind of condition they are in. 129 00:10:55,490 --> 00:10:56,490 [GRUNTING] 130 00:10:56,650 --> 00:11:00,970 HUMBLE: Oh, my goodness! What a magnificent beast. 131 00:11:02,610 --> 00:11:05,730 The male bison at this time of year, 132 00:11:06,250 --> 00:11:11,130 are truly... Just they are in their prime. 133 00:11:13,850 --> 00:11:19,730 Bulls have piled on up to 150 kilograms of fat and muscle, 134 00:11:19,810 --> 00:11:23,610 and now is their chance to start throwing that weight around. 135 00:11:26,050 --> 00:11:31,090 July is rutting season, when males duel for the right to mate, 136 00:11:31,170 --> 00:11:35,690 and this year's favourable conditions mean it will be fierce. 137 00:11:36,810 --> 00:11:39,690 The largest contenders could be tipping the scales 138 00:11:39,770 --> 00:11:41,450 at nearly a ton. 139 00:11:44,090 --> 00:11:46,410 You may think, "Isn't it a little bit early for sex?" 140 00:11:46,490 --> 00:11:49,010 I mean, you know, it's the summer, they should be chilling out, 141 00:11:49,090 --> 00:11:53,050 but remember, the bison are the first to give birth. 142 00:11:53,970 --> 00:11:56,970 Think back to the spring, the first calves we saw, 143 00:11:57,050 --> 00:11:58,370 they were bison calves. 144 00:12:01,490 --> 00:12:05,370 Female bison have one of the longest pregnancies here, 145 00:12:05,450 --> 00:12:07,370 lasting over nine months. 146 00:12:09,330 --> 00:12:13,250 So, to time the birth of calves, with the start of next spring, 147 00:12:15,410 --> 00:12:17,770 these males need to get on with it. 148 00:12:26,890 --> 00:12:31,210 This male bison found himself the perfect dust bath. 149 00:12:35,130 --> 00:12:37,530 And, at various times, throughout the day, 150 00:12:37,610 --> 00:12:40,570 he will roll in it. He will cover himself in dust, 151 00:12:40,730 --> 00:12:42,770 he'll pee in the dust and roll in that. 152 00:12:46,850 --> 00:12:52,010 Just to make sure that he smells as virile and ready for it as possible. 153 00:12:53,250 --> 00:12:54,530 [GRUNTING] 154 00:12:59,410 --> 00:13:04,010 Wallowing in dust baths is a show of strength. 155 00:13:09,330 --> 00:13:12,970 Each male competes to churn up the biggest dust cloud, 156 00:13:13,050 --> 00:13:15,370 and intimidate its rivals. 157 00:13:19,330 --> 00:13:22,570 But when two heavyweights won't back down, 158 00:13:22,650 --> 00:13:24,570 they go head to head. 159 00:13:29,170 --> 00:13:34,330 Heavily muscled necks and thick skulls covered in a mat of dense hair, 160 00:13:34,410 --> 00:13:38,330 help absorb the colossal forces of each collision. 161 00:13:42,370 --> 00:13:46,610 Only the winner earns the right to mate. 162 00:13:54,690 --> 00:13:59,330 This ensures the strongest genes will be passed on. 163 00:14:03,570 --> 00:14:07,330 Whilst I've been following herds of prey animals on the plateau, 164 00:14:08,810 --> 00:14:11,530 our camera crews are at lower altitudes 165 00:14:11,610 --> 00:14:16,850 on the trail of Yellowstone's top predator, the wolf. 166 00:14:19,450 --> 00:14:24,090 Over 500 wolves roam across Greater Yellowstone. 167 00:14:24,170 --> 00:14:28,530 The mild winter and spring caused many packs to go hungry, 168 00:14:28,650 --> 00:14:32,530 as the prey was well-fed and could outrun the wolves. 169 00:14:34,690 --> 00:14:40,010 In summer, the stakes are even higher because there are young pups to feed. 170 00:14:43,090 --> 00:14:45,290 In the south of Greater Yellowstone, 171 00:14:45,370 --> 00:14:48,250 biologists have been studying one wolf pack 172 00:14:48,330 --> 00:14:52,690 that seems to be defying the odds and thriving this year. 173 00:14:52,770 --> 00:14:54,690 The Pinnacle Peak Pack. 174 00:14:56,170 --> 00:14:59,490 This photo was taken during an aerial survey. 175 00:14:59,570 --> 00:15:02,530 It reveals the pack has eleven pups. 176 00:15:02,610 --> 00:15:06,650 Unusually, two females have given birth this year, 177 00:15:06,770 --> 00:15:09,730 a sign this pack is doing well. 178 00:15:11,090 --> 00:15:13,610 All the adults take it in turns to hunt, 179 00:15:13,690 --> 00:15:17,330 and return to the den sites with meat for the pups. 180 00:15:17,410 --> 00:15:20,770 But the elk that make up the majority of wolves prey, 181 00:15:20,850 --> 00:15:23,370 have moved to higher grazing grounds. 182 00:15:27,490 --> 00:15:31,170 The biologists have been observing how the pack finds enough food 183 00:15:31,250 --> 00:15:33,410 for all 11 pups. 184 00:15:33,490 --> 00:15:37,290 They've directed wildlife cameraman, Charlie Hamilton James, 185 00:15:37,370 --> 00:15:40,730 to an area where they've seen remarkable behaviour. 186 00:15:41,810 --> 00:15:44,650 They think the key to the wolves success here, 187 00:15:44,810 --> 00:15:47,570 could be down to human activity. 188 00:15:55,810 --> 00:15:57,730 [WHISPERING] 189 00:16:02,330 --> 00:16:04,170 -See it? -[ENGINE STOPS] 190 00:16:10,770 --> 00:16:13,850 Uh... How's she gonna let me get out? 191 00:16:15,330 --> 00:16:17,010 I'm gonna give it a go. 192 00:16:18,370 --> 00:16:19,530 Bear with me on this. 193 00:16:21,450 --> 00:16:22,730 [DOOR OPENS SLOWLY] 194 00:16:56,570 --> 00:16:58,250 How beautiful is that? 195 00:16:58,730 --> 00:17:02,370 She can smell me, my scent is going straight at her. 196 00:17:02,570 --> 00:17:04,530 She knows I'm here. 197 00:17:04,610 --> 00:17:06,090 She's not bothered at all. 198 00:17:09,610 --> 00:17:11,730 HUMBLE: In all his 20 years of filming, 199 00:17:11,810 --> 00:17:15,210 Charlie has never been this close to a wild wolf. 200 00:17:19,570 --> 00:17:22,570 This female is from the Pinnacle Peak Pack. 201 00:17:25,890 --> 00:17:28,050 And something has drawn her here. 202 00:17:32,650 --> 00:17:34,490 The grass is still green, 203 00:17:34,570 --> 00:17:38,450 because it's being watered over the summer to improve grazing. 204 00:17:41,010 --> 00:17:42,410 [SNARLING] 205 00:17:46,890 --> 00:17:51,130 You see the sprinklers behind her, 'cause they're watering the grass. 206 00:17:51,210 --> 00:17:53,490 This creates amazing habitat for ground squirrels. 207 00:17:53,730 --> 00:17:55,130 It's just tons of them. 208 00:18:02,210 --> 00:18:06,210 HUMBLE: A huge colony of grass-eating winter ground squirrels 209 00:18:06,290 --> 00:18:08,810 is exploiting this artificial oasis. 210 00:18:11,050 --> 00:18:15,730 Usually, by mid-July, the grass would be turning brown and inedible. 211 00:18:16,490 --> 00:18:19,890 The squirrels would have started entering the burrows to hibernate, 212 00:18:20,410 --> 00:18:21,530 but not here. 213 00:18:24,610 --> 00:18:28,530 This female wolf has spotted the chance of an easy meal, 214 00:18:31,290 --> 00:18:35,570 and it's closer to the pups than the large elk herds, 20 miles away. 215 00:18:36,010 --> 00:18:37,970 [SQUIRREL SQUEAKS] 216 00:18:45,130 --> 00:18:48,210 They need these ground squirrels, 'cause they're tied to their territory. 217 00:18:48,290 --> 00:18:50,410 They got pups here, they can't go anywhere else, 218 00:18:50,490 --> 00:18:52,130 so they have to find food around here. 219 00:18:53,490 --> 00:18:55,810 Just to survive, and keep those pups alive. 220 00:18:58,730 --> 00:19:02,370 HUMBLE: But catching these burrowing rodents is tricky. 221 00:19:05,770 --> 00:19:08,810 They spend much of their time looking for danger. 222 00:19:09,290 --> 00:19:13,050 Balancing on their hind legs to see over the tall grass. 223 00:19:19,650 --> 00:19:24,330 The squirrels also have a range of alarm calls for different threats. 224 00:19:29,810 --> 00:19:32,050 [SQUEAKING] 225 00:19:33,610 --> 00:19:37,090 A trill means it's a ground based predator. 226 00:19:37,530 --> 00:19:38,850 [SQUEAKING] 227 00:19:41,770 --> 00:19:45,130 The entire colony dive for the safety of their burrows. 228 00:19:51,850 --> 00:19:54,290 She's on it. She's on one. Oh! 229 00:19:59,010 --> 00:20:01,730 HUMBLE: This female is putting in a lot of work, 230 00:20:01,810 --> 00:20:03,610 but without any reward. 231 00:20:07,130 --> 00:20:09,570 Oh, there's another one there again, there's one running. 232 00:20:09,770 --> 00:20:12,650 Ah, where is it, where is it? Long way off. 233 00:20:20,770 --> 00:20:24,170 HUMBLE: Another pack member may help turn the tables. 234 00:20:24,650 --> 00:20:27,690 Wolves real strength is when they hunt together. 235 00:20:41,370 --> 00:20:43,810 JAMES: There's another one. [LAUGHS] 236 00:20:45,210 --> 00:20:46,530 Look, there's another wolf. 237 00:20:58,930 --> 00:21:00,810 I don't know which one to film then. 238 00:21:02,690 --> 00:21:04,650 [SQUEAKING] 239 00:21:05,970 --> 00:21:09,850 HUMBLE: The ground squirrels can't watch all three wolves at once. 240 00:21:14,650 --> 00:21:19,090 And these new comers are also trying a different hunting strategy, 241 00:21:19,170 --> 00:21:20,890 to outwit their quarry. 242 00:21:22,490 --> 00:21:23,490 [SQUEAKS] 243 00:21:29,250 --> 00:21:33,170 There's a lot of activity, and then they'll lie down, 244 00:21:33,250 --> 00:21:35,290 and you'll think, "Well, why are they suddenly lying down?" 245 00:21:40,690 --> 00:21:42,450 It's part of their hunting strategy. 246 00:21:42,530 --> 00:21:45,050 You just lie down, and essentially just wait for the ground squirrels 247 00:21:45,130 --> 00:21:46,930 to come up to them. 248 00:21:47,010 --> 00:21:49,530 You know, that's so dozing... A ground squirrels comes up, 249 00:21:49,610 --> 00:21:51,650 and they just leap out and grab it. [LAUGHS] 250 00:22:00,930 --> 00:22:02,410 HUMBLE: It's working. 251 00:22:04,010 --> 00:22:05,010 [SQUEAKS] 252 00:22:05,530 --> 00:22:08,730 Even the original female is having more luck. 253 00:22:19,810 --> 00:22:23,250 JAMES: With animals, you get these peak moments of activity, 254 00:22:23,330 --> 00:22:27,730 and they last for few days or few weeks, and then they're gone again. 255 00:22:27,810 --> 00:22:32,130 And it's incredibly lucky that we've been able to be here 256 00:22:32,210 --> 00:22:35,730 for this particular period of peak activity. 257 00:22:35,810 --> 00:22:37,050 I've never seen it before. 258 00:22:37,130 --> 00:22:40,250 I don't know if it'll ever happen again but it's amazing to witness it. 259 00:22:47,330 --> 00:22:49,890 HUMBLE: These wolves have used all their intelligence 260 00:22:49,970 --> 00:22:52,090 to exploit this situation. 261 00:23:01,530 --> 00:23:04,610 The food will increase the pups chance of survival. 262 00:23:05,810 --> 00:23:06,810 [SQUEAKS] 263 00:23:17,410 --> 00:23:21,290 And more wolves means a stronger pack next year. 264 00:23:34,290 --> 00:23:35,770 ARYEE: It's early July, 265 00:23:35,850 --> 00:23:38,130 and no rain has fallen this month at the Snake river, 266 00:23:38,610 --> 00:23:40,610 but the beavers have their home. 267 00:23:42,090 --> 00:23:44,850 This, combined with the early snow melt, 268 00:23:44,930 --> 00:23:48,290 means that the river is running 20% below its average. 269 00:23:50,850 --> 00:23:54,090 If the level of the beavers main pond drops too low, 270 00:23:54,450 --> 00:23:56,570 it could expose the entrance to their lodge, 271 00:23:56,650 --> 00:23:58,250 which is usually under water. 272 00:23:58,810 --> 00:24:02,290 And this would make them easy pickings for predators. 273 00:24:06,450 --> 00:24:10,050 Jeff is watching them closely to see how they react. 274 00:24:11,610 --> 00:24:15,370 HOGAN: Oh, look. Wow! That's mum. 275 00:24:16,690 --> 00:24:20,090 ARYEE: And it looks like mum has made an executive decision. 276 00:24:20,570 --> 00:24:24,570 She's got one of the kits in her mouth. She's heading towards the dam. 277 00:24:25,130 --> 00:24:27,650 ARYEE: She's moving one of her kits out of the pond, 278 00:24:27,810 --> 00:24:30,010 maybe to search for a new home. 279 00:24:36,290 --> 00:24:38,170 HOGAN: This is incredible. 280 00:24:42,850 --> 00:24:44,130 And there they go. 281 00:24:44,770 --> 00:24:46,010 I'm gonna go chase 'em. 282 00:24:49,370 --> 00:24:52,650 ARYEE: Scientists have observed beaver families relocating, 283 00:24:52,730 --> 00:24:56,930 but Jeff has never witnessed it in 20 years of studying them. 284 00:24:57,290 --> 00:25:01,610 Out in the open, kits are vulnerable to predators like bald eagles. 285 00:25:01,890 --> 00:25:04,730 It's a tense moment for mum and her young. 286 00:25:11,610 --> 00:25:12,610 Here they come. 287 00:25:15,170 --> 00:25:17,730 ARYEE: The beaver family's territory is large, 288 00:25:17,810 --> 00:25:20,330 with fives dams and pools along this river. 289 00:25:21,450 --> 00:25:23,490 HOGAN: She's gonna crawl over this next dam. 290 00:25:31,890 --> 00:25:33,610 [GRUNTS] 291 00:25:40,810 --> 00:25:43,970 ARYEE: After travelling more than 350 metres, 292 00:25:44,930 --> 00:25:46,930 and crossing three more dams, 293 00:25:48,770 --> 00:25:52,410 Jeff films her mum leading her kit, up a small channel, 294 00:25:52,650 --> 00:25:54,090 that comes off the main river. 295 00:25:55,290 --> 00:25:59,010 They're gonna climb right up through this cascading stream, 296 00:25:59,970 --> 00:26:01,850 waddling up through the stones... 297 00:26:01,930 --> 00:26:04,290 You can see that the beavers don't do quite so well in land, 298 00:26:04,370 --> 00:26:06,690 especially this river rock. 299 00:26:07,130 --> 00:26:09,370 They do so much better in the water. 300 00:26:11,810 --> 00:26:15,690 Unreal, never seen this... Ever. 301 00:26:16,770 --> 00:26:17,890 And there they go. 302 00:26:21,290 --> 00:26:25,410 ARYEE: Later, at night, Jeff checks his camera in the lodge. 303 00:26:26,050 --> 00:26:27,050 Let's see. 304 00:26:34,090 --> 00:26:37,450 ARYEE: It reveals mum has moved all the kits, 305 00:26:37,570 --> 00:26:40,410 and the whole family has abandoned their home. 306 00:26:45,770 --> 00:26:50,130 Jeff is now on a mission to find out where the beavers have gone, 307 00:26:50,210 --> 00:26:54,890 if the kits survive, and whether this huge gamble will pay off. 308 00:26:59,330 --> 00:27:02,730 HUMBLE: Whilst the low lying rivers and grasslands are sweltering 309 00:27:02,810 --> 00:27:05,290 in temperatures of nearly 30 degrees, 310 00:27:06,090 --> 00:27:11,930 2,000 metres up Yellowstone peaks have a recent dusting of fresh snow. 311 00:27:14,250 --> 00:27:17,330 And the mountain meadows are a riot of colour. 312 00:27:29,410 --> 00:27:34,530 It is amazing, the contrast up here to down in the valley. 313 00:27:34,610 --> 00:27:37,330 Down in the valley, summer has really taken grip. 314 00:27:37,410 --> 00:27:41,730 The temperatures are quite high and the grass is starting to go brown. 315 00:27:41,810 --> 00:27:46,170 But up here, 800 metres higher, it's a totally different story. 316 00:27:46,250 --> 00:27:50,890 It's breezy, it's cool, and look at all these magnificent wild flowers. 317 00:28:02,850 --> 00:28:05,090 Susan Marsh is a naturalist, 318 00:28:05,170 --> 00:28:11,890 and she pays very close attention to these high-altitude wild flowers. 319 00:28:11,970 --> 00:28:14,570 Where most people see pretty petals, 320 00:28:14,650 --> 00:28:16,810 Susan sees a living record 321 00:28:16,890 --> 00:28:21,290 of how this ecosystem is being affected by this year's weather 322 00:28:21,370 --> 00:28:23,530 and the changing climate. 323 00:28:26,250 --> 00:28:27,970 We've looked a lot 324 00:28:28,050 --> 00:28:32,650 at how animals can indicate the state of how a year is progressing 325 00:28:32,730 --> 00:28:34,730 as far as the weather is concerned. 326 00:28:34,810 --> 00:28:37,450 Are the plants just as valuable as indicators? 327 00:28:37,530 --> 00:28:39,610 Yes, um, I think they are, 328 00:28:39,690 --> 00:28:41,970 and the one advantage that they have, in my opinion, 329 00:28:42,050 --> 00:28:43,370 is that they don't run off. 330 00:28:43,450 --> 00:28:45,730 -HUMBLE: [LAUGHING] Yes, very true! -And they don't fly away. 331 00:28:45,850 --> 00:28:48,610 So, I can tell by how tall they are, first of all. 332 00:28:48,690 --> 00:28:50,730 -Right. -Uh, this one is fireweed. 333 00:28:50,810 --> 00:28:52,810 -Okay. -And it typically, 334 00:28:52,890 --> 00:28:55,970 in a really lush year, will grow head-high. 335 00:28:56,050 --> 00:28:57,890 -Wow. -Even at this elevation. 336 00:28:58,130 --> 00:29:02,050 And these particular ones, you can see, are only a couple feet tall. 337 00:29:02,130 --> 00:29:05,010 -Yeah, yeah. -And, to me, that's an indication 338 00:29:05,090 --> 00:29:07,130 of heat and dryness. 339 00:29:07,210 --> 00:29:11,690 The plant needs to set seed, and it has a very short growing season, 340 00:29:11,770 --> 00:29:15,730 so it's not gonna waste its energy making a big, tall stalk 341 00:29:15,810 --> 00:29:17,730 -or making great, big leaves. -Right. 342 00:29:17,810 --> 00:29:20,650 These leaves are small this year, smaller than usual. 343 00:29:23,850 --> 00:29:25,050 HUMBLE: Through these plants, 344 00:29:25,130 --> 00:29:28,490 Susan can chart this year's erratic weather. 345 00:29:28,730 --> 00:29:33,170 But can plants also indicate larger changes? 346 00:29:33,290 --> 00:29:36,810 Everyone is talking about the fact that the climate is changing. 347 00:29:37,170 --> 00:29:41,010 Is that something that is becoming evident in the plants? 348 00:29:41,290 --> 00:29:43,410 MARSH: It's typically on the mountaintops. 349 00:29:43,490 --> 00:29:46,010 -So that's above the treeline? -Above the trees, 350 00:29:46,290 --> 00:29:49,970 where there's rocks, and wind, and cold. 351 00:29:54,170 --> 00:29:56,490 HUMBLE: It's the coldest part of Yellowstone, 352 00:29:56,570 --> 00:29:59,010 above 3,000 metres, 353 00:29:59,130 --> 00:30:03,490 where Susan is seeing the effects of climate change hit hard. 354 00:30:07,410 --> 00:30:13,010 This is the alpine zone, a realm of high-altitude specialists. 355 00:30:15,010 --> 00:30:17,130 But as temperatures keep getting warmer, 356 00:30:17,690 --> 00:30:22,090 non-specialist plants are able to survive higher up the mountains, 357 00:30:22,170 --> 00:30:25,530 and they're invading this fragile zone. 358 00:30:28,410 --> 00:30:31,890 Does it concern you that you are seeing 359 00:30:31,970 --> 00:30:35,250 a march towards a very different climate, 360 00:30:35,330 --> 00:30:38,370 and therefore, a very different ecosystem? 361 00:30:38,570 --> 00:30:40,850 I think there'll be some good and some bad 362 00:30:40,930 --> 00:30:43,890 depending on what species you are, as climate change continues. 363 00:30:43,970 --> 00:30:47,370 But, yes, I don't want to lose the wild flower parks that I love. 364 00:30:47,450 --> 00:30:49,010 I don't want to lose the alpine zone. 365 00:30:49,090 --> 00:30:50,130 [BUZZING] 366 00:30:51,770 --> 00:30:55,770 I don't want to see those go, but I don't think I can stop it. 367 00:31:00,370 --> 00:31:03,850 HUMBLE: Climatologists studying Greater Yellowstone 368 00:31:03,930 --> 00:31:07,370 have charted temperatures increasing by nearly a fifth of a degree 369 00:31:07,450 --> 00:31:08,530 every decade. 370 00:31:09,690 --> 00:31:15,370 This seemingly small change is having far-reaching consequences. 371 00:31:15,450 --> 00:31:16,810 Across Yellowstone, 372 00:31:16,890 --> 00:31:21,010 scientists are seeing how animals are being forced to adapt. 373 00:31:23,450 --> 00:31:24,450 [GROWLING] 374 00:31:24,530 --> 00:31:27,810 Even the most iconic species like the grizzly bear, 375 00:31:27,890 --> 00:31:30,090 are being affected. 376 00:31:31,570 --> 00:31:33,570 To find out what's going on, 377 00:31:33,650 --> 00:31:36,450 Patrick has gone to the Gallatin Mountain range 378 00:31:36,530 --> 00:31:38,770 in the north-west of Greater Yellowstone. 379 00:31:42,290 --> 00:31:45,010 ARYEE: I've come to meet our bear expert, Casey Anderson, 380 00:31:46,090 --> 00:31:49,770 to see how one group of grizzly bears is coping 381 00:31:49,850 --> 00:31:53,290 as the changing climate threatens an important food source. 382 00:31:55,290 --> 00:31:57,330 If you look up at this knob up here... 383 00:31:57,570 --> 00:32:00,730 Yeah, take a look at the trees just around the bottom of that. 384 00:32:00,810 --> 00:32:03,370 -Those are white bark pine. -ARYEE: Let's have a look. 385 00:32:06,170 --> 00:32:09,410 ANDERSON: That entire forest of white bark pine, ancient trees, 386 00:32:09,490 --> 00:32:11,810 some of them are 300 years old, 387 00:32:11,890 --> 00:32:14,650 they've all died in the last couple of years. 388 00:32:14,730 --> 00:32:16,490 They're gone. 389 00:32:17,610 --> 00:32:20,290 ARYEE: What's caused it to die off? 390 00:32:20,490 --> 00:32:23,210 Well, there's a pine beetle that's always existed up there, 391 00:32:23,290 --> 00:32:24,810 but we've had these cold winters 392 00:32:25,290 --> 00:32:28,690 that have usually just killed most of the beetles. 393 00:32:28,770 --> 00:32:31,690 But now with climate change, those winters are not as harsh, 394 00:32:31,930 --> 00:32:33,970 we're not having that beetle-kill that we're used to 395 00:32:34,050 --> 00:32:35,210 in the middle of the winter, 396 00:32:35,290 --> 00:32:38,250 so the beetles are really starting to infest the forest. 397 00:32:40,010 --> 00:32:43,050 ARYEE: Pine beetles are no bigger that grains of rice, 398 00:32:43,570 --> 00:32:47,730 but these small creatures cause big problems. 399 00:32:47,810 --> 00:32:50,610 Not only do their young eat the trees' living tissue, 400 00:32:50,690 --> 00:32:53,850 but they also introduce a destructive fungus. 401 00:32:53,930 --> 00:32:58,650 Eventually, this combination kills the entire tree. 402 00:32:58,850 --> 00:33:01,090 This is bad news for the animals 403 00:33:01,170 --> 00:33:04,210 that rely on the food and shelter this tree provides. 404 00:33:07,970 --> 00:33:11,690 Towards the end of summer, as other food sources dry up, 405 00:33:11,770 --> 00:33:15,930 these pine nuts usually provide vital protein for grizzlies. 406 00:33:22,050 --> 00:33:23,610 One aerial survey 407 00:33:23,690 --> 00:33:28,210 revealed around 80% of mature whitebark trees in Greater Yellowstone 408 00:33:28,290 --> 00:33:32,130 show signs of moderate to severe beetle infestation. 409 00:33:32,210 --> 00:33:35,370 To survive, the bears must adapt. 410 00:33:36,650 --> 00:33:40,090 And Casey has witnessed some intriguing behaviour. 411 00:33:42,610 --> 00:33:45,090 Grizzlies are leaving the wilderness 412 00:33:45,170 --> 00:33:47,770 to congregate on this cattle ranch to feed. 413 00:33:53,810 --> 00:33:56,330 ANDERSON: What they're eating is this caraway root 414 00:33:56,410 --> 00:33:57,970 that actually came in with the livestock. 415 00:33:58,050 --> 00:34:00,690 It's actually an introduced species not native to the area, 416 00:34:00,770 --> 00:34:02,530 and they're coming down and taking advantage of it. 417 00:34:04,690 --> 00:34:05,850 And all the bears in the area 418 00:34:05,930 --> 00:34:07,650 are starting to migrate towards this meadow 419 00:34:07,730 --> 00:34:10,330 because there's not a lot of food out there in the summer. 420 00:34:10,410 --> 00:34:12,690 But right here, this is like a bear buffet. 421 00:34:12,770 --> 00:34:14,890 ARYEE: It's a race against time. 422 00:34:14,970 --> 00:34:17,970 The bears must pile on enough fat 423 00:34:18,050 --> 00:34:21,730 to see them through five months of hibernation. 424 00:34:21,810 --> 00:34:24,890 While the root is at its most abundant in summer and autumn, 425 00:34:24,970 --> 00:34:27,850 the grizzlies gorge throughout the night, 426 00:34:27,930 --> 00:34:31,250 eating up to 20,000 calories in a single sitting. 427 00:34:40,530 --> 00:34:42,130 As the day heats up, 428 00:34:43,650 --> 00:34:47,490 the hot sun forces them back into the shady forest to rest. 429 00:34:52,410 --> 00:34:55,890 But Casey and our mobile camera team 430 00:34:56,690 --> 00:35:00,530 have seen two bears that are still out in the midday sun. 431 00:35:02,450 --> 00:35:04,250 MAN: [OVER RADIO] Hey, Casey, do you copy? 432 00:35:05,130 --> 00:35:07,010 [BEARS GROWLING PLAYFULLY] 433 00:35:07,610 --> 00:35:10,010 They're, like, totally tumblin' around out there. 434 00:35:13,010 --> 00:35:16,250 [LAUGHS] Well, little playful guys. 435 00:35:22,690 --> 00:35:25,370 [BEARS GROWLING PLAYFULLY] 436 00:35:26,130 --> 00:35:28,930 ARYEE: These two yearlings are orphans. 437 00:35:29,010 --> 00:35:32,010 Unfortunately, their mum died last autumn. 438 00:35:32,130 --> 00:35:35,970 But against the odds, they've turned up in this meadow. 439 00:35:36,050 --> 00:35:38,890 I've joined Casey to see how they're doing. 440 00:35:39,690 --> 00:35:41,650 Well, they're right here. 441 00:35:41,730 --> 00:35:45,930 There's two yearling grizzly cubs right out here, digging around. 442 00:35:46,010 --> 00:35:47,850 ARYEE: [WHISPERING] Oh, yeah! Right there! 443 00:35:51,050 --> 00:35:54,650 They're still young and inexperienced. 444 00:35:54,770 --> 00:35:58,930 Cubs usually stay with their mums for up to three and a half years, 445 00:35:59,010 --> 00:36:00,690 but even with this protection, 446 00:36:00,770 --> 00:36:03,450 almost a third won't survive in Yellowstone. 447 00:36:05,570 --> 00:36:10,850 It's a miracle that these two made it through an entire winter on their own. 448 00:36:18,290 --> 00:36:20,570 I mean, do you think that having one another 449 00:36:20,650 --> 00:36:23,770 is one of the reasons why they've made it this far? 450 00:36:23,850 --> 00:36:25,850 I think it's gotta be one of the biggest reasons. 451 00:36:28,650 --> 00:36:29,730 If they didn't have each other, 452 00:36:29,810 --> 00:36:32,290 I don't think there's any chance that one of them would've survived. 453 00:36:32,650 --> 00:36:34,090 Yeah, they've got each other's back. 454 00:36:40,290 --> 00:36:42,770 ARYEE: Whilst feeding on this working ranch, 455 00:36:42,850 --> 00:36:45,690 there are lots of unusual sights and sounds. 456 00:36:46,570 --> 00:36:47,770 [COWS MOOING] 457 00:36:49,170 --> 00:36:50,490 [WHIPPING] 458 00:36:52,930 --> 00:36:54,850 But without a mum to teach them, 459 00:36:54,930 --> 00:36:58,690 it's hard for the cubs to know what is and isn't dangerous. 460 00:37:02,210 --> 00:37:04,850 ANDERSON: You find yourself really worrying about them 461 00:37:06,650 --> 00:37:09,010 because they don't have that notorious mama grizzly 462 00:37:09,090 --> 00:37:10,250 -looking out for 'em. -Mmm. 463 00:37:19,450 --> 00:37:21,690 Yeah, they're looking a little bit nervous. 464 00:37:21,770 --> 00:37:23,050 It's like they're looking at something 465 00:37:23,850 --> 00:37:25,490 over in the distance. 466 00:37:28,330 --> 00:37:31,330 ANDERSON: They obviously sense something in that direction. 467 00:37:31,410 --> 00:37:33,450 I think that these two have probably been chased 468 00:37:33,530 --> 00:37:35,050 probably once a day by something, 469 00:37:35,130 --> 00:37:38,010 whether it's another grizzly, a pack of wolves, 470 00:37:38,090 --> 00:37:39,770 or even cattle. 471 00:37:46,050 --> 00:37:50,450 ARYEE: Surprisingly, the dangers may not come from the ranchers or their cattle. 472 00:37:52,250 --> 00:37:55,530 Most have learnt to live alongside their grizzly neighbours. 473 00:37:57,890 --> 00:38:02,130 One of the biggest threats comes in the form of other bears 474 00:38:02,370 --> 00:38:04,650 close by in the shade of the forests. 475 00:38:08,250 --> 00:38:12,930 A big, male grizzly, known as a boar, could kill and eat the cubs. 476 00:38:13,010 --> 00:38:17,610 But it looks like these two have found a way to avoid this danger. 477 00:38:17,970 --> 00:38:20,250 The big boars and other bears are out at night 478 00:38:20,330 --> 00:38:23,250 'cause when it's hot like this, most bears will not come out and dig 479 00:38:23,330 --> 00:38:24,450 'cause it just wears 'em out. 480 00:38:26,650 --> 00:38:29,170 And as the sun comes up, they go back to the forest, 481 00:38:29,250 --> 00:38:31,690 while these little guys, they're kind of on the opposite schedule. 482 00:38:32,690 --> 00:38:34,650 The danger goes away, it's time to eat. 483 00:38:38,530 --> 00:38:41,770 "Let's do it in the heat of the day when there's nothing else out here. 484 00:38:41,850 --> 00:38:43,370 "We don't have to worry about anything." 485 00:38:43,570 --> 00:38:45,290 And that's what they're doing, and it's working for 'em. 486 00:38:45,370 --> 00:38:46,690 It's an amazing strategy. 487 00:38:51,410 --> 00:38:54,330 ARYEE: The two cubs are a fantastic indicator 488 00:38:54,410 --> 00:38:56,610 of just how intelligent bears can be. 489 00:38:58,650 --> 00:39:01,850 Even as climate change kills off the whitebark pine, 490 00:39:01,930 --> 00:39:05,530 the bears are adapting to exploit new opportunities. 491 00:39:07,090 --> 00:39:10,250 With over 700 grizzlies in Greater Yellowstone, 492 00:39:10,330 --> 00:39:13,090 the latest data suggests their population, 493 00:39:13,170 --> 00:39:16,210 for now at least, has remained stable. 494 00:39:24,970 --> 00:39:29,650 HUMBLE: Yellowstone hasn't reached its record temperature of 36 degrees, 495 00:39:31,730 --> 00:39:35,170 but climate data has revealed that July this year 496 00:39:35,250 --> 00:39:39,690 was the seventh month in a row with above-average temperatures. 497 00:39:47,170 --> 00:39:50,850 The relentless heat and the early thaw 498 00:39:51,090 --> 00:39:52,970 are a dangerous combination. 499 00:39:55,370 --> 00:39:58,810 They may create perfect conditions 500 00:40:00,890 --> 00:40:02,690 for wildfires. 501 00:40:06,010 --> 00:40:09,210 In normal years, the snow melt would come down off the mountains 502 00:40:09,330 --> 00:40:11,170 and it would hang around places like this, 503 00:40:11,250 --> 00:40:14,450 soaking into all this dead wood, but not this year. 504 00:40:14,530 --> 00:40:17,090 What it did, was come rushing off in a great torrent 505 00:40:17,170 --> 00:40:19,770 into the rivers, into the streams, into the lakes, 506 00:40:19,850 --> 00:40:24,650 and it didn't have time to soak into all this dead, dry wood. 507 00:40:24,730 --> 00:40:28,610 So this is basically fuel for fires. 508 00:40:28,690 --> 00:40:31,850 And having so much dead, dry wood around 509 00:40:31,930 --> 00:40:36,330 means that there is a danger, this year, of bigger and more intense fires. 510 00:40:36,450 --> 00:40:38,250 [THUNDER RUMBLING] 511 00:40:39,010 --> 00:40:42,690 A single spark could set this landscape alight. 512 00:40:44,050 --> 00:40:48,730 Every summer, an average of 26 wildfires are started by lightning 513 00:40:48,810 --> 00:40:51,170 across Yellowstone National Park. 514 00:40:56,450 --> 00:40:59,970 Our crew are out following up on reports of wildfire. 515 00:41:02,490 --> 00:41:04,810 Flames can reach heights of 50 metres, 516 00:41:04,890 --> 00:41:08,170 exceed 1,200 degrees Celsius, 517 00:41:08,250 --> 00:41:11,650 and rip through the landscape at up to 14 miles per hour. 518 00:41:12,450 --> 00:41:17,850 By mid-August, the tinder-dry conditions means five major fires have taken hold 519 00:41:17,930 --> 00:41:20,210 and are raging across the region. 520 00:41:22,610 --> 00:41:24,850 ARYEE: In the Beartooth Mountains 521 00:41:24,930 --> 00:41:27,650 is wildlife cameraman Jeff Hogan. 522 00:41:27,730 --> 00:41:29,050 Oh, no, this is nuts! 523 00:41:30,450 --> 00:41:34,570 ARYEE: He's filming a wildfire that's consuming a huge area of forest, 524 00:41:35,970 --> 00:41:38,970 and it's headed straight towards the family of great grey owls 525 00:41:39,050 --> 00:41:41,050 he's been following since spring. 526 00:41:50,050 --> 00:41:52,450 This fire is huge and it's raging, 527 00:41:52,530 --> 00:41:56,210 and it's right in the backyard of our great grey owl family. 528 00:41:56,290 --> 00:41:58,290 This is really a threat. 529 00:41:59,850 --> 00:42:01,570 [SCREECHING] 530 00:42:04,370 --> 00:42:08,210 ARYEE: So far, the chicks have done much better than expected. 531 00:42:10,170 --> 00:42:15,690 There was only a 20% chance all three would make it out of the nest. 532 00:42:15,770 --> 00:42:18,770 [WHISPERING] Oh, he's gonna go, he's gonna go! Jump, jump! 533 00:42:21,650 --> 00:42:23,170 Oh, wow! 534 00:42:23,970 --> 00:42:26,570 ARYEE: Jeff thought their biggest challenges were over... 535 00:42:32,730 --> 00:42:33,970 [FIRE CRACKLING] 536 00:42:34,050 --> 00:42:37,450 ...but now, he'll have to wait until the fire's died down 537 00:42:37,530 --> 00:42:39,530 to see if these young owls survive. 538 00:42:43,890 --> 00:42:45,450 Oh, my goodness! 539 00:42:47,650 --> 00:42:50,610 The aftermath of a fire might seem devastating, 540 00:42:50,690 --> 00:42:53,490 but it's actually part of the forest's natural cycle. 541 00:42:53,850 --> 00:42:56,490 It brings growth and new life. 542 00:42:56,570 --> 00:43:00,450 All this ash is actually really fertile, 543 00:43:00,530 --> 00:43:01,930 and as soon as it rains, 544 00:43:02,010 --> 00:43:05,050 new green shoots are going to start popping up, 545 00:43:05,330 --> 00:43:08,650 and that's going to encourage grazers like elk and deer 546 00:43:08,730 --> 00:43:12,290 to come into this area, and eventually, grizzly bears. 547 00:43:12,370 --> 00:43:13,490 But not only that. 548 00:43:13,570 --> 00:43:18,290 Some plants have actually evolved to benefit from fires. 549 00:43:18,370 --> 00:43:21,810 These here are lodgepole pine cones, 550 00:43:21,890 --> 00:43:25,730 and they only open up once they reach a specific temperature 551 00:43:25,810 --> 00:43:28,610 that can only be produced by a fire. 552 00:43:28,690 --> 00:43:31,770 And then these seeds will eventually fall off 553 00:43:31,850 --> 00:43:35,930 down into the ground and be fertilised by the ash. 554 00:43:38,530 --> 00:43:41,490 Fires are a natural part of life here. 555 00:43:42,130 --> 00:43:44,210 But by the time they die down, 556 00:43:44,290 --> 00:43:48,050 they will have burnt nearly 100 square miles of land. 557 00:43:49,210 --> 00:43:50,570 This year's fires 558 00:43:50,650 --> 00:43:54,610 will have been the most destructive inside Yellowstone National Park 559 00:43:54,690 --> 00:43:56,850 since 1988. 560 00:43:56,930 --> 00:44:01,490 Large scale fires used to sweep through the park around every 300 years. 561 00:44:02,370 --> 00:44:05,410 But scientists now believe that the warming climate 562 00:44:05,530 --> 00:44:09,010 could result in them happening every three to five years 563 00:44:09,090 --> 00:44:10,890 by the end of this century. 564 00:44:12,890 --> 00:44:15,810 This could result in the destruction of the forest 565 00:44:15,890 --> 00:44:20,210 that's home to the fragile population of great grey owls. 566 00:44:23,370 --> 00:44:26,850 Jeff is searching the area at the edge of the burn 567 00:44:26,930 --> 00:44:29,130 for any sign of the owl family. 568 00:44:34,650 --> 00:44:37,130 There's a lot of ground to cover, 569 00:44:37,210 --> 00:44:40,890 so Jeff calls in expert animal tracker Dan Hartman. 570 00:44:43,210 --> 00:44:46,610 After four days searching, 571 00:44:46,690 --> 00:44:50,450 Dan finally hears an adult great grey. 572 00:44:52,330 --> 00:44:53,690 [OWL SCREECHING] 573 00:44:58,090 --> 00:45:01,490 And close by, one of the young owls. 574 00:45:03,490 --> 00:45:04,930 [SCREECHING] 575 00:45:11,890 --> 00:45:15,010 After another few minutes watching and listening, 576 00:45:15,090 --> 00:45:17,330 he spots the other two siblings. 577 00:45:22,570 --> 00:45:24,250 [SCREECHING] 578 00:45:24,890 --> 00:45:26,450 [SCREECHING] 579 00:45:30,530 --> 00:45:33,090 All of them have survived. 580 00:45:33,610 --> 00:45:35,050 [OWL SCREECHING] 581 00:45:36,850 --> 00:45:40,370 And they're even making their first attempts at hunting. 582 00:45:48,770 --> 00:45:52,530 The owl chicks have all made it through their first summer, 583 00:45:52,610 --> 00:45:56,490 but we still don't know the fate of the beaver mum and her three kits. 584 00:46:01,490 --> 00:46:04,330 I've joined Jeff on a tributary of the Snake River 585 00:46:05,850 --> 00:46:09,170 where he's seen signs that the beavers are making a new home. 586 00:46:10,610 --> 00:46:12,650 He thinks it's a safer location 587 00:46:12,730 --> 00:46:16,010 as the water level is higher than at their old pond. 588 00:46:19,370 --> 00:46:20,930 [QUACKING] 589 00:46:33,570 --> 00:46:34,930 HOGAN: Oh, look! 590 00:46:38,210 --> 00:46:40,570 There's your beaver. It's sitting there by the stack. 591 00:46:40,650 --> 00:46:42,450 ARYEE: Oh, my... It's that beaver there! 592 00:46:43,250 --> 00:46:44,610 That's the beaver right there. 593 00:46:44,930 --> 00:46:47,610 ARYEE: This is just gold dust. 594 00:46:49,090 --> 00:46:50,930 This looks like mum, 595 00:46:51,010 --> 00:46:55,170 and in the few weeks since moving, the family has been busy building. 596 00:47:00,330 --> 00:47:02,570 HOGAN: That is a new lodge being built right now. 597 00:47:02,650 --> 00:47:05,170 They just make a big pile of sticks, 598 00:47:05,250 --> 00:47:07,810 then they go into it and start digging it out, 599 00:47:07,890 --> 00:47:09,850 and they'll pile mud and stuff up on top of it. 600 00:47:11,810 --> 00:47:15,250 This is a lodge at its early stages. 601 00:47:15,490 --> 00:47:16,770 HOGAN: This is rare. 602 00:47:16,850 --> 00:47:21,610 Rarely do you see the very early stages of a whole new beaver pond 603 00:47:21,690 --> 00:47:23,610 with a lodge like this. 604 00:47:27,210 --> 00:47:29,850 ARYEE: They're concentrating on their dam, 605 00:47:29,930 --> 00:47:32,250 strengthening it with rocks 606 00:47:32,330 --> 00:47:34,530 and plugging any leaks with weeds and mud 607 00:47:34,610 --> 00:47:36,770 to create a deep, wide pond. 608 00:47:38,330 --> 00:47:40,530 The water table here is rising 609 00:47:40,610 --> 00:47:43,170 so that they can reach out and get more of this food, 610 00:47:43,250 --> 00:47:47,010 the trees that grow around here, cottonwoods, alders, willows. 611 00:47:47,610 --> 00:47:50,650 ARYEE: The beavers can now access all this untapped food 612 00:47:53,010 --> 00:47:56,850 without having to venture far onto dry land where they're vulnerable. 613 00:48:02,530 --> 00:48:03,810 HOGAN: [WHISPERING] There's a beaver right there! 614 00:48:03,890 --> 00:48:06,970 ARYEE: Finally, Jeff spots what we've both been hoping to see. 615 00:48:07,050 --> 00:48:08,330 -[WHISPERING] Running up there. -Oh, yes. 616 00:48:08,410 --> 00:48:09,490 There's a new one! 617 00:48:09,570 --> 00:48:10,770 -There's a young one. -Yes, yes, yes! 618 00:48:12,850 --> 00:48:14,290 ARYEE: Whoa! 619 00:48:26,650 --> 00:48:29,730 We've got our three young beavers right here, the three kits. 620 00:48:33,250 --> 00:48:34,810 They're getting big. 621 00:48:34,890 --> 00:48:36,170 -They are. -They're getting big, fast. 622 00:48:39,090 --> 00:48:44,170 ARYEE: Mum's risky gamble appears to have paid off. 623 00:48:44,250 --> 00:48:47,210 This deep pond, with a new lodge, 624 00:48:47,290 --> 00:48:49,130 and plenty of food, 625 00:48:49,210 --> 00:48:51,770 is everything the kits will need to thrive. 626 00:48:53,610 --> 00:48:56,010 They're so inquisitive, aren't they? 627 00:48:58,050 --> 00:49:01,930 And they're just... They're just fabulous to watch. 628 00:49:10,570 --> 00:49:13,810 The kits will stay with their parents for the next two years. 629 00:49:13,890 --> 00:49:17,370 In that time, they'll learn the engineering skills needed 630 00:49:17,450 --> 00:49:19,770 to build a dam and a lodge. 631 00:49:21,610 --> 00:49:23,570 The secret to the beavers' success 632 00:49:23,650 --> 00:49:27,330 is adapting the landscape to suit their needs. 633 00:49:30,730 --> 00:49:35,930 It's engineering on a scale that has only been surpassed by humans. 634 00:49:43,930 --> 00:49:47,890 HUMBLE: Every year, the challenges in Yellowstone are getting greater 635 00:49:47,970 --> 00:49:52,250 as climate change results in more extreme weather. 636 00:49:52,890 --> 00:49:57,530 Yellowstone's residents have developed clever strategies to survive, 637 00:49:57,610 --> 00:49:59,730 but the last animal I want to see 638 00:50:00,010 --> 00:50:03,690 is quickly running out of options as temperatures rise. 639 00:50:07,890 --> 00:50:12,930 I've come up to 3,000 metres and the fragile alpine zone. 640 00:50:16,410 --> 00:50:22,170 Only one specialist mammal is active up here all year round. 641 00:50:22,250 --> 00:50:23,530 The pika. 642 00:50:23,730 --> 00:50:25,010 [CAMERA SHUTTER CLICKING] 643 00:50:31,010 --> 00:50:35,410 And Kaitlyn Hanley is the hardy researcher who studies them. 644 00:50:39,770 --> 00:50:42,810 I've got glimpses of pika. 645 00:50:42,890 --> 00:50:44,210 Are they a member of the rabbit family? 646 00:50:44,290 --> 00:50:45,650 They're called the "rock rabbits." 647 00:50:45,730 --> 00:50:46,810 -[PIKA CALLING] -Oh, there was one. 648 00:50:46,970 --> 00:50:49,410 -That was a call? -[LAUGHS] Yeah, that was a pika. 649 00:50:50,130 --> 00:50:51,810 Come on, come on, Kaitlyn. I want you to scout... 650 00:50:51,890 --> 00:50:52,970 There he is. He's right there! 651 00:50:53,050 --> 00:50:54,330 HUMBLE: Oh, my goodness! There he is! 652 00:51:07,170 --> 00:51:11,450 Pikas are thought to evolved from ancestors in Siberia, 653 00:51:11,530 --> 00:51:14,290 one of the coldest places on Earth. 654 00:51:18,970 --> 00:51:22,730 Their odd appearance is all about keeping warm. 655 00:51:24,370 --> 00:51:25,690 [PIKA CALLING] 656 00:51:26,090 --> 00:51:29,490 A plump, round shape minimises surface heat loss 657 00:51:30,730 --> 00:51:33,330 and thick fur covers their entire bodies, 658 00:51:34,210 --> 00:51:35,890 even their toes! 659 00:51:38,970 --> 00:51:43,050 For pikas, summer is all about collecting food. 660 00:51:46,010 --> 00:51:47,810 I imagine, that up here, 661 00:51:47,890 --> 00:51:51,570 the season where there's any food at all is pretty short. 662 00:51:51,650 --> 00:51:54,130 Yes, and they don't hibernate in the winter, 663 00:51:54,210 --> 00:51:57,330 so they actually collect hay through the entire summer 664 00:51:58,810 --> 00:52:01,170 and they'll use that as their food source during the winter. 665 00:52:01,250 --> 00:52:02,450 HUMBLE: So that's what they're doing now? 666 00:52:02,530 --> 00:52:03,690 HANLEY: Yes, they're haying, yeah. 667 00:52:05,730 --> 00:52:07,890 They'll get these huge hay piles under their rocks 668 00:52:07,970 --> 00:52:10,370 and they'll that in the winter and eat. 669 00:52:10,450 --> 00:52:11,770 -HUMBLE: Really? -Yeah, they're the only mammal 670 00:52:11,850 --> 00:52:13,650 that doesn't hibernate up this high. 671 00:52:16,970 --> 00:52:18,530 HUMBLE: And they can survive? HANLEY: Yes, they survive. 672 00:52:18,610 --> 00:52:21,130 I mean, the snow must come here, what, in October? 673 00:52:21,210 --> 00:52:23,410 Yes, it would be October most of the time. 674 00:52:23,490 --> 00:52:25,530 -Through to... -March-May. 675 00:52:27,810 --> 00:52:30,730 So they've got a matter of months to collect enough hay 676 00:52:30,810 --> 00:52:33,450 to get them through the whole of the winter? 677 00:52:33,530 --> 00:52:34,690 HANLEY: Yes. 678 00:52:34,770 --> 00:52:36,930 They're busy little bees, that's for sure. 679 00:52:39,970 --> 00:52:42,770 HUMBLE: Pikas love a cool climate. 680 00:52:42,850 --> 00:52:47,530 Just a few hours' exposure to temperatures of 21 degrees 681 00:52:47,610 --> 00:52:49,730 can prove fatal. 682 00:52:49,930 --> 00:52:54,650 So they can only exist in Yellowstone above 2,000 metres. 683 00:52:55,330 --> 00:52:56,490 [CALLING] 684 00:52:56,570 --> 00:53:01,010 Soon, even here, they may have nowhere left to go. 685 00:53:02,650 --> 00:53:05,890 Because these animals are such high-alpine specialists, 686 00:53:05,970 --> 00:53:08,970 they can't survive at the lower elevations. 687 00:53:09,050 --> 00:53:11,130 Does that make them particularly vulnerable 688 00:53:11,210 --> 00:53:13,370 to things like climatic changes? 689 00:53:13,450 --> 00:53:15,930 Absolutely. They are very sensitive to heat, 690 00:53:16,530 --> 00:53:21,490 and so, as climate change and the habitat changes for them, 691 00:53:21,730 --> 00:53:23,250 they're gonna move up-slope. 692 00:53:25,010 --> 00:53:28,370 They're already up-slope at this point! You can't go any farther. 693 00:53:28,450 --> 00:53:32,010 And so, for the pika, you know, they don't have anywhere to move. 694 00:53:32,450 --> 00:53:34,050 They're running into the sky. 695 00:53:39,370 --> 00:53:42,410 HUMBLE: Scientists have already seen pikas disappear 696 00:53:42,490 --> 00:53:45,170 from one-third of their former strongholds 697 00:53:45,250 --> 00:53:47,330 in warmer states to the south. 698 00:53:48,610 --> 00:53:52,890 But Yellowstone's high country still provides sanctuary, 699 00:53:52,970 --> 00:53:54,730 at least for now. 700 00:53:57,170 --> 00:53:58,370 HANLEY: I have hope. 701 00:53:58,650 --> 00:54:00,170 I... I don't think we should lose hope. 702 00:54:00,250 --> 00:54:02,850 -[BOTH GIGGLING] -'Cause they're too cute to go extinct. 703 00:54:02,930 --> 00:54:04,690 [BOTH LAUGHING] 704 00:54:04,770 --> 00:54:09,770 That's one very good reason we should all be there to save the pika, 705 00:54:09,850 --> 00:54:11,930 is that it's just too cute to go extinct! 706 00:54:13,890 --> 00:54:15,410 [CALLING] 707 00:54:21,530 --> 00:54:25,570 ARYEE: The arrival of autumn marks the end of the great thaw. 708 00:54:27,250 --> 00:54:30,170 We've seen how the dramatic seasonal changes 709 00:54:30,250 --> 00:54:32,690 affected Yellowstone's wildlife. 710 00:54:34,050 --> 00:54:37,170 The mild winter meant the wolves struggled to hunt 711 00:54:37,250 --> 00:54:38,970 strong, well-fed prey, 712 00:54:41,170 --> 00:54:42,450 and many went hungry. 713 00:54:43,690 --> 00:54:45,450 [HOWLING] 714 00:54:46,610 --> 00:54:49,890 But in the summer, they used their cunning to find food 715 00:54:50,930 --> 00:54:52,610 and keep their pups alive. 716 00:54:55,850 --> 00:54:59,210 The beavers survived the spring run-off, 717 00:54:59,290 --> 00:55:02,370 and were able to build an entirely new home 718 00:55:02,450 --> 00:55:03,810 to raise their three kits. 719 00:55:07,330 --> 00:55:08,330 [SCREECHING] 720 00:55:08,410 --> 00:55:11,730 Our great grey owl runt beat all the odds 721 00:55:11,810 --> 00:55:14,050 and fledged with its two siblings, 722 00:55:16,290 --> 00:55:19,930 giving this vulnerable population a much-needed boost. 723 00:55:22,770 --> 00:55:25,690 The grizzly bears' race to fatten up started early 724 00:55:25,970 --> 00:55:27,810 with the mild winter conditions. 725 00:55:28,850 --> 00:55:32,890 The wet spring and early green-up revealed a bounty of food. 726 00:55:33,650 --> 00:55:38,170 But by summer, they had to use all their resourcefulness to survive. 727 00:55:40,650 --> 00:55:44,490 This has been a magical window into the lives of wildlife 728 00:55:44,570 --> 00:55:47,090 in a truly spectacular landscape. 729 00:55:49,810 --> 00:55:52,610 HUMBLE: We've also seen a bigger picture unfold 730 00:55:52,930 --> 00:55:54,850 as scientists try to predict 731 00:55:54,930 --> 00:55:59,250 what the future for Yellowstone will look like as the climate shifts. 732 00:56:01,370 --> 00:56:04,210 I think what we do know is all of it's gonna change, 733 00:56:04,290 --> 00:56:05,970 and it's changing pretty rapidly, 734 00:56:06,050 --> 00:56:08,650 and we don't really know how it's gonna change. 735 00:56:08,970 --> 00:56:12,090 There'll be some good and some bad depending on what species you are, 736 00:56:12,170 --> 00:56:13,530 as climate change continues. 737 00:56:15,810 --> 00:56:18,650 HUMBLE: There are still many challenges ahead, 738 00:56:20,490 --> 00:56:24,570 but if there is one thing that all of Yellowstone's animals share, 739 00:56:24,650 --> 00:56:29,290 it's their incredible ability to adapt to extreme change, 740 00:56:31,530 --> 00:56:35,050 and this will give them the best possible chance to survive 741 00:56:35,610 --> 00:56:37,490 whatever the future brings.