1 00:00:06,240 --> 00:00:09,742 MORGAN: They're our planet's first builders, 2 00:00:09,744 --> 00:00:12,144 nature's architects and engineers, 3 00:00:12,146 --> 00:00:14,680 crafting homes of spectacular design 4 00:00:14,682 --> 00:00:16,582 in every corner of the globe. 5 00:00:16,584 --> 00:00:21,620 Some are elegantly simple, others surprisingly complex. 6 00:00:21,622 --> 00:00:24,556 So it looks like a teenager's bedroom from the outside, 7 00:00:24,558 --> 00:00:25,758 but if you were to cut this 8 00:00:25,760 --> 00:00:27,593 right down the middle and look inside... 9 00:00:27,595 --> 00:00:30,295 Whether they were made by beaks or paws, 10 00:00:30,297 --> 00:00:32,831 these homes have a universal purpose -- 11 00:00:32,833 --> 00:00:34,400 to keep their owners safe 12 00:00:34,402 --> 00:00:36,201 from a dangerous world 13 00:00:36,203 --> 00:00:39,104 as they give birth and raise a family. 14 00:00:39,106 --> 00:00:40,439 It makes it a perfect bear home. 15 00:00:40,441 --> 00:00:42,941 It's secure, it's dry. 16 00:00:42,943 --> 00:00:47,112 And it turns out that the quest for real estate in the wild 17 00:00:47,114 --> 00:00:50,416 is all about the same three things we value most -- 18 00:00:50,418 --> 00:00:53,619 location, location, location. 19 00:00:53,621 --> 00:00:56,488 A strategic location in space... 20 00:00:59,126 --> 00:01:02,394 At a precise location in time... 21 00:01:02,396 --> 00:01:04,797 These are the essential must-haves 22 00:01:04,799 --> 00:01:07,533 of just the right home. 23 00:01:27,755 --> 00:01:32,691 It looks like an ideal place to live, doesn't it? 24 00:01:32,693 --> 00:01:36,161 The valley of the Snake River -- 25 00:01:36,163 --> 00:01:38,931 Jackson Hole, Wyoming. 26 00:01:38,933 --> 00:01:43,035 t features beautiful Rocky Mountain views, 27 00:01:43,037 --> 00:01:45,704 plenty of running water, 28 00:01:45,706 --> 00:01:49,274 and a good mix of trees and shrubbery. 29 00:01:51,512 --> 00:01:55,447 It's the perfect spot to build your dream house 30 00:01:55,449 --> 00:01:59,651 and to commune with nature. 31 00:01:59,653 --> 00:02:01,186 The surprising thing is, 32 00:02:01,188 --> 00:02:05,224 much of what you see here isn't exactly natural. 33 00:02:05,226 --> 00:02:10,028 It was shaped and crafted by a rodent -- 34 00:02:10,030 --> 00:02:13,165 the beaver. 35 00:02:13,167 --> 00:02:19,838 This is where a family of beavers is making its home. 36 00:02:19,840 --> 00:02:24,910 The dad has been homesteading here for nearly a decade, 37 00:02:24,912 --> 00:02:30,549 and he and his mate have a couple of kits. 38 00:02:30,551 --> 00:02:33,585 Their ancestors have been 39 00:02:33,587 --> 00:02:37,856 working this area for thousands of years. 40 00:02:42,163 --> 00:02:44,930 For this family, like all homeowners, 41 00:02:44,932 --> 00:02:46,565 location is crucial. 42 00:02:49,170 --> 00:02:52,271 For once they chose this spot, they set about 43 00:02:52,273 --> 00:02:54,406 giving it a complete makeover 44 00:02:54,408 --> 00:02:58,677 to meet their exacting specifications. 45 00:03:03,050 --> 00:03:04,516 I'm Chris Morgan. 46 00:03:04,518 --> 00:03:07,519 I'm an ecologist and I'm fascinated by 47 00:03:07,521 --> 00:03:10,189 how animals construct their homes 48 00:03:10,191 --> 00:03:15,127 and why they decide to live where they do. 49 00:03:15,129 --> 00:03:17,262 There he is. 50 00:03:17,264 --> 00:03:20,799 There's our inhabitant. 51 00:03:20,801 --> 00:03:28,640 Beavers are very choosy about where they build. 52 00:03:28,642 --> 00:03:33,512 There's one thing no beaver can do without. 53 00:03:33,514 --> 00:03:36,548 It's top of the list in their real-estate requirements, 54 00:03:36,550 --> 00:03:39,551 and that's a stream. 55 00:03:39,553 --> 00:03:42,988 When beavers hear the sound of running water, 56 00:03:42,990 --> 00:03:46,792 they feel compelled to build. 57 00:03:46,794 --> 00:03:50,462 But before they start work on their house, 58 00:03:50,464 --> 00:03:53,232 they first build a dam. 59 00:03:53,234 --> 00:03:55,567 And check out this dam. 60 00:03:55,569 --> 00:03:58,170 It's amazing! It's huge! 61 00:03:58,172 --> 00:04:01,473 Beavers are the only mammals besides humans 62 00:04:01,475 --> 00:04:03,008 that construct dams 63 00:04:03,010 --> 00:04:05,177 to block water. 64 00:04:05,179 --> 00:04:07,012 [Laugh] 65 00:04:07,014 --> 00:04:09,181 And they build big ones. 66 00:04:09,183 --> 00:04:13,051 A beaver dam can be hundreds of feet long, 67 00:04:13,053 --> 00:04:15,988 and it's strong enough to support me. 68 00:04:15,990 --> 00:04:18,290 It is such an impressive construction. 69 00:04:18,292 --> 00:04:20,592 I mean, look at this. It's packed with 70 00:04:20,594 --> 00:04:23,662 big logs down to these tiny twigs, 71 00:04:23,664 --> 00:04:26,999 and every single of of them -- look -- 72 00:04:27,001 --> 00:04:28,667 has been chewed off by a beaver. 73 00:04:28,669 --> 00:04:30,769 These are all different building materials, 74 00:04:30,771 --> 00:04:33,672 and one of the most impressive to me is the fact that 75 00:04:33,674 --> 00:04:36,308 these beavers will swim with and push and hoist 76 00:04:36,310 --> 00:04:39,144 these giants rocks -- look at the size of that -- 77 00:04:39,146 --> 00:04:41,046 right onto the top of the dam. 78 00:04:41,048 --> 00:04:43,715 And they use these big rocks as anchors, 79 00:04:43,717 --> 00:04:45,384 along with the giant logs, 80 00:04:45,386 --> 00:04:48,253 and then they intersperse it with mud and grass 81 00:04:48,255 --> 00:04:50,989 and other debris -- look at that, perfect -- 82 00:04:50,991 --> 00:04:53,659 and create this watertight system 83 00:04:53,661 --> 00:04:56,561 with one idea in mind, and that is to 84 00:04:56,563 --> 00:04:59,731 bring the water level up behind this dam. 85 00:04:59,733 --> 00:05:01,233 And the difference between 86 00:05:01,235 --> 00:05:03,669 this water level and that water level 87 00:05:03,671 --> 00:05:06,171 is approaching, I'd guess, three feet. 88 00:05:06,173 --> 00:05:07,873 It's quite something. 89 00:05:07,875 --> 00:05:11,843 These beavers are not only designers and architects, 90 00:05:11,845 --> 00:05:15,981 but stonemasons, woodworkers, builders. 91 00:05:15,983 --> 00:05:17,683 They do it all. 92 00:05:17,685 --> 00:05:22,421 The dam converts a stream into a pond. 93 00:05:22,423 --> 00:05:24,656 Wow. 94 00:05:24,658 --> 00:05:27,693 That's just the place to live if you're a water-loving, 95 00:05:27,695 --> 00:05:28,894 web-footed beaver 96 00:05:28,896 --> 00:05:31,930 who's much better at swimming than walking. 97 00:05:31,932 --> 00:05:36,735 Now that the pond's nice and deep, 98 00:05:36,737 --> 00:05:39,404 the beaver family instinctively shift gears 99 00:05:39,406 --> 00:05:43,842 to start working on their house -- the lodge. 100 00:05:46,647 --> 00:05:50,582 With all this construction work, they need a lot of wood. 101 00:05:50,584 --> 00:05:55,787 Fortunately, their ancestors evolved into lumberjacks, 102 00:05:55,789 --> 00:05:59,024 and they work the night shift. 103 00:06:07,701 --> 00:06:09,401 Since the tender 104 00:06:09,403 --> 00:06:13,205 inner bark of trees is a beaver's favorite food, 105 00:06:13,207 --> 00:06:17,309 they can harvest a crop while they gather lumber. 106 00:06:17,311 --> 00:06:19,277 Watch out! 107 00:06:24,451 --> 00:06:28,220 But there is a limit to how much they can drag, 108 00:06:28,222 --> 00:06:32,124 so our clever beavers let the water do the work. 109 00:06:37,664 --> 00:06:40,699 When you think about it, it's really not a stretch 110 00:06:40,701 --> 00:06:42,968 to call these guys hydro-engineers. 111 00:06:42,970 --> 00:06:44,936 So they'll excavate these channels. 112 00:06:44,938 --> 00:06:46,838 Look at this. They've actually dug the mud 113 00:06:46,840 --> 00:06:48,440 out of this with their front paws. 114 00:06:48,442 --> 00:06:51,209 They'll float these big logs out, 115 00:06:51,211 --> 00:06:54,980 back to where the dam is and where the lodge is, 116 00:06:54,982 --> 00:06:57,382 and it allows them as an aquatic mammal 117 00:06:57,384 --> 00:07:00,419 to swim up these channels and access the new trees. 118 00:07:00,421 --> 00:07:04,489 What an awesome system. 119 00:07:04,491 --> 00:07:09,127 By damming the stream so it floods its banks 120 00:07:09,129 --> 00:07:11,663 and then digging a network of canals, 121 00:07:11,665 --> 00:07:15,500 the beavers have devised a way to swim right into the forest 122 00:07:15,502 --> 00:07:17,169 to reach more trees. 123 00:07:17,171 --> 00:07:18,804 It's a watery world. 124 00:07:18,806 --> 00:07:20,038 And through their efforts, 125 00:07:20,040 --> 00:07:22,207 they've also reshaped the entire neighborhood, 126 00:07:22,209 --> 00:07:28,480 transforming a woodland into a wetland. 127 00:07:58,512 --> 00:08:03,648 Of course, beavers don't work from a blueprint, 128 00:08:03,650 --> 00:08:08,854 but they certainly seem to have one in mind. 129 00:08:08,856 --> 00:08:12,657 And since this pair has built dams and lodges before, 130 00:08:12,659 --> 00:08:17,429 their instincts are bolstered by experience. 131 00:08:20,234 --> 00:08:21,867 This is the heart of it all, 132 00:08:21,869 --> 00:08:24,135 the heart of the beaver neighborhood. 133 00:08:24,137 --> 00:08:25,637 Look at the size of this. 134 00:08:25,639 --> 00:08:26,771 This is the lodge. 135 00:08:26,773 --> 00:08:27,973 My goodness. 136 00:08:27,975 --> 00:08:30,642 It looks like a total jumbled mess of logs, 137 00:08:30,644 --> 00:08:32,677 kind of like a volcano of logs. 138 00:08:32,679 --> 00:08:36,047 They've stripped off the bark and eaten the inner bark. 139 00:08:36,049 --> 00:08:37,682 Look at those teeth marks. 140 00:08:37,684 --> 00:08:40,252 And then they use their food, the food waste, 141 00:08:40,254 --> 00:08:42,487 as building material, so it looks like 142 00:08:42,489 --> 00:08:44,723 a teenager's bedroom from the outside, 143 00:08:44,725 --> 00:08:47,459 but if you were to cut this right down the middle 144 00:08:47,461 --> 00:08:48,994 and look inside... 145 00:08:48,996 --> 00:08:53,164 You'd see just how complex it is. 146 00:08:53,166 --> 00:08:56,668 This lodge is build up against the pond's shore, 147 00:08:56,670 --> 00:09:01,840 but the entrances are underwater for security. 148 00:09:01,842 --> 00:09:04,476 Above is a suite of rooms. 149 00:09:04,478 --> 00:09:09,180 Amazingly, the beavers actually carve them from the inside, 150 00:09:09,182 --> 00:09:12,584 chewing and clawing their way through 151 00:09:12,586 --> 00:09:15,820 that solid mound of wood and earth. 152 00:09:15,822 --> 00:09:19,591 There's a kind of a mud room, where they can dry off, 153 00:09:19,593 --> 00:09:24,329 and a family room, where they eat and sleep. 154 00:09:24,331 --> 00:09:26,698 They left the domed roof a little loose 155 00:09:26,700 --> 00:09:32,470 to vent out CO2 and to let in fresh air. 156 00:09:32,472 --> 00:09:35,307 And as a finishing touch, they'll excavate the mud 157 00:09:35,309 --> 00:09:37,642 on the shore side to create a moat 158 00:09:37,644 --> 00:09:41,112 so their home will be completely surrounded by water. 159 00:09:46,587 --> 00:09:51,323 Beaver lodges are all built around the same general lines, 160 00:09:51,325 --> 00:09:55,860 but each one is unique, 161 00:09:55,862 --> 00:10:01,933 a designer home that's perfectly matched to its surroundings. 162 00:10:01,935 --> 00:10:05,470 The goal is to have a house that's cozy and warm, 163 00:10:05,472 --> 00:10:08,640 safe and secure, where they can raise 164 00:10:08,642 --> 00:10:12,310 their young ones -- in fact, the same things 165 00:10:12,312 --> 00:10:15,814 that motivate every house-building animal. 166 00:10:15,816 --> 00:10:19,451 But finding just the right location to build in, 167 00:10:19,453 --> 00:10:21,019 that's the challenge. 168 00:10:21,021 --> 00:10:26,191 Most animals can't do what beavers do. 169 00:10:28,795 --> 00:10:30,428 They can't alter their neighborhood 170 00:10:30,430 --> 00:10:31,463 to meet their needs. 171 00:10:36,670 --> 00:10:40,472 So they have to make the best use of their habitat, 172 00:10:40,474 --> 00:10:45,377 taking advantage of whatever nature offers. 173 00:10:50,517 --> 00:10:53,251 This red-faced warbler has found a convenient spot 174 00:10:53,253 --> 00:10:54,519 to raise her family -- 175 00:10:54,521 --> 00:10:57,355 right on the ground, 176 00:10:57,357 --> 00:11:02,594 tucked away under a fallen branch. 177 00:11:02,596 --> 00:11:06,531 The warbler's neighbor, a brown creeper, 178 00:11:06,533 --> 00:11:09,034 takes an entirely different approach. 179 00:11:09,036 --> 00:11:12,937 It climbs straight up a tree trunk 180 00:11:12,939 --> 00:11:16,474 to hide its nest inside the bark. 181 00:11:18,278 --> 00:11:20,078 And these house finches 182 00:11:20,080 --> 00:11:24,249 make their home among the spines of a cholla cactus. 183 00:11:24,251 --> 00:11:28,687 That's like putting up a barbed-wire fence 184 00:11:28,689 --> 00:11:31,189 to keep out trespassers. 185 00:11:31,191 --> 00:11:34,059 Of course, 186 00:11:34,061 --> 00:11:37,062 the conditions where you live help determine 187 00:11:37,064 --> 00:11:40,432 where you put your home. 188 00:11:42,436 --> 00:11:45,370 A great desert skink escapes the searing heat 189 00:11:45,372 --> 00:11:47,072 of the Australian Outback 190 00:11:47,074 --> 00:11:51,109 by digging a network of underground tunnels. 191 00:11:51,111 --> 00:11:54,079 Down here, it can be nearly 40 degrees cooler 192 00:11:54,081 --> 00:11:55,914 than up on the surface. 193 00:11:55,916 --> 00:12:00,919 A gopher tortoise makes its home underground too 194 00:12:00,921 --> 00:12:05,457 because the pine forest it lives in is prone to fire. 195 00:12:11,898 --> 00:12:14,899 No matter where you make your home, 196 00:12:14,901 --> 00:12:16,801 your surroundings are bound to present 197 00:12:16,803 --> 00:12:19,571 both challenges and opportunities. 198 00:12:21,408 --> 00:12:27,412 A good homemaker knows how to deal with both. 199 00:12:30,917 --> 00:12:34,285 The salt marsh sparrow makes its nest, 200 00:12:34,287 --> 00:12:35,854 not surprisingly, 201 00:12:35,856 --> 00:12:39,891 in coastal salt marshes from Maine to Virginia. 202 00:12:43,363 --> 00:12:47,532 A house near the shore offers a lot of attractions, 203 00:12:47,534 --> 00:12:49,901 but it also harbors risks. 204 00:12:53,573 --> 00:12:58,109 This is a place where ocean and land collide, 205 00:12:58,111 --> 00:13:01,412 a place of constant change and powerful forces. 206 00:13:03,717 --> 00:13:07,218 As a home site, it has its drawbacks. 207 00:13:07,220 --> 00:13:10,822 You see, the female sparrow 208 00:13:10,824 --> 00:13:14,192 builds her nest on the ground, 209 00:13:14,194 --> 00:13:15,960 and the marsh floods with the tide. 210 00:13:22,769 --> 00:13:25,503 Twice each day, the pull of the moon 211 00:13:25,505 --> 00:13:29,207 draws the sea into the marsh. 212 00:13:29,209 --> 00:13:33,545 And twice each month, when the moon is full, 213 00:13:33,547 --> 00:13:38,583 and again when it's new, the tides are especially high. 214 00:13:42,155 --> 00:13:46,691 Nesting here is certainly risky. 215 00:13:46,693 --> 00:13:50,161 But on the other hand, there's less competition 216 00:13:50,163 --> 00:13:53,698 for space and food, so this is where the sparrow 217 00:13:53,700 --> 00:13:55,466 has carved out a niche. 218 00:13:58,405 --> 00:14:02,240 She's in a race against time and the rising tide. 219 00:14:05,645 --> 00:14:08,847 The sparrow weaves her nest under the top layer of grass 220 00:14:08,849 --> 00:14:11,649 so it's hidden from predators 221 00:14:11,651 --> 00:14:15,086 but high enough so it should stay above water. 222 00:14:18,625 --> 00:14:20,425 It takes 24 to 26 days 223 00:14:20,427 --> 00:14:23,127 from the time she begins laying her eggs 224 00:14:23,129 --> 00:14:25,096 until her last chicks fledge -- 225 00:14:25,098 --> 00:14:30,635 almost the exact length of the lunar cycle. 226 00:14:32,105 --> 00:14:33,905 There's no margin for error. 227 00:14:39,546 --> 00:14:43,214 For most of the sparrow nests, 228 00:14:43,216 --> 00:14:47,752 flooding is inevitable. 229 00:15:03,203 --> 00:15:06,337 It can be a disaster. 230 00:15:10,610 --> 00:15:13,745 A female sparrow has no way to get her eggs 231 00:15:13,747 --> 00:15:16,614 back into the nest if they float away. 232 00:15:19,085 --> 00:15:21,586 That's why the nest is constructed with 233 00:15:21,588 --> 00:15:26,291 an overhanging dome to make sure the eggs stay put. 234 00:15:29,229 --> 00:15:32,964 As long as they remain within the confines of the nest, 235 00:15:32,966 --> 00:15:38,937 they can bob around for an hour or two until the tide recedes. 236 00:15:38,939 --> 00:15:42,740 When mom returns, she'll warm them up, 237 00:15:42,742 --> 00:15:46,811 and they'll continue to incubate. 238 00:15:50,951 --> 00:15:53,351 After the eggs hatch, the chicks have 239 00:15:53,353 --> 00:15:55,820 no protective shell to float around in, 240 00:15:55,822 --> 00:15:58,256 so they're more vulnerable than ever. 241 00:16:21,214 --> 00:16:23,548 Young chicks can't swim. 242 00:16:23,550 --> 00:16:27,685 They're defenseless against the rising water. 243 00:16:33,426 --> 00:16:36,060 But once they're about five days old, 244 00:16:36,062 --> 00:16:37,729 they're strong enough to climb up above 245 00:16:37,731 --> 00:16:41,799 a flooded nest and wait out the tide. 246 00:16:50,777 --> 00:16:53,578 This chick has made it through the night. 247 00:16:53,580 --> 00:16:55,913 She was just big enough to reach safety. 248 00:16:55,915 --> 00:17:00,084 Her siblings weren't so lucky. 249 00:17:08,828 --> 00:17:11,262 A few inches can make all the difference 250 00:17:11,264 --> 00:17:16,200 between a successful nest and a catastrophic failure. 251 00:17:21,875 --> 00:17:23,975 But enough sparrows survive 252 00:17:23,977 --> 00:17:26,811 to keep the little birds coming back to these marshes 253 00:17:26,813 --> 00:17:28,279 year after year. 254 00:17:42,395 --> 00:17:45,163 One creature that lives on the water 255 00:17:45,165 --> 00:17:47,565 but avoids the problems of a flooded nest 256 00:17:47,567 --> 00:17:48,933 is the hooded merganser. 257 00:17:48,935 --> 00:17:52,170 Mergansers are striking little ducks, 258 00:17:52,172 --> 00:17:54,572 especially the males, 259 00:17:54,574 --> 00:17:57,775 with their black-and-white crests. 260 00:17:57,777 --> 00:18:04,115 In the spring, they puff them up to attract a mate. 261 00:18:09,589 --> 00:18:12,990 Once courtship is over, 262 00:18:12,992 --> 00:18:18,296 house-hunting and child-rearing are left up to the female. 263 00:18:18,298 --> 00:18:23,334 Most water fowl build their nests on the ground 264 00:18:23,336 --> 00:18:26,370 or on floating mats of vegetation, 265 00:18:26,372 --> 00:18:31,943 but hooded mergansers are rare ducks. 266 00:18:31,945 --> 00:18:35,480 They seek out the shelter of a hollow tree. 267 00:18:35,482 --> 00:18:38,416 Out of the thousands of trees in this forest, 268 00:18:38,418 --> 00:18:40,618 this one is perfect. 269 00:18:40,620 --> 00:18:44,922 Struck by lightning years ago, it still stands tall, 270 00:18:44,924 --> 00:18:46,958 with a convenient entrance 271 00:18:46,960 --> 00:18:48,159 50 feet up. 272 00:18:48,161 --> 00:18:51,295 A woodpecker probably drilled out that hole 273 00:18:51,297 --> 00:18:53,498 while it foraged for insects. 274 00:18:55,735 --> 00:18:59,871 Over time, the hole's been widened and rubbed smooth, 275 00:18:59,873 --> 00:19:03,374 perhaps by squirrels or raccoons... 276 00:19:05,245 --> 00:19:09,614 And by generations of hooded merganser moms. 277 00:19:12,619 --> 00:19:14,585 At the bottom of the cavity, 278 00:19:14,587 --> 00:19:17,355 she lines her nest with soft down features 279 00:19:17,357 --> 00:19:19,157 plucked from her own breast, 280 00:19:19,159 --> 00:19:23,861 and here she lays a clutch of eggs, 281 00:19:23,863 --> 00:19:25,763 up to a dozen or so. 282 00:19:25,765 --> 00:19:29,000 Mergansers can afford to lay so many eggs 283 00:19:29,002 --> 00:19:31,302 because they nest in a location 284 00:19:31,304 --> 00:19:35,072 that's safe from the elements and from predators. 285 00:19:38,912 --> 00:19:41,946 After four or five weeks, 286 00:19:41,948 --> 00:19:44,048 the eggs begin to open. 287 00:19:48,955 --> 00:19:51,756 Once hatching is underway, 288 00:19:51,758 --> 00:19:54,091 the nest is a busy place, 289 00:19:54,093 --> 00:19:56,093 and noisy. 290 00:19:56,095 --> 00:19:57,728 [Chirping] 291 00:19:57,730 --> 00:19:59,730 All that vocalizing promotes 292 00:19:59,732 --> 00:20:02,800 a family bond, as the ducklings get used to 293 00:20:02,802 --> 00:20:06,537 the sound of their mother's voice. 294 00:20:06,539 --> 00:20:09,373 She won't stay in the nest for long, though. 295 00:20:13,346 --> 00:20:15,213 Within hours of the last egg hatching, 296 00:20:15,215 --> 00:20:18,282 the ducklings are home alone. 297 00:20:22,989 --> 00:20:25,056 Their mother's not far away, 298 00:20:25,058 --> 00:20:27,758 and her calls 299 00:20:27,760 --> 00:20:30,628 are the only thing that could entice them 300 00:20:30,630 --> 00:20:32,463 to abandon their cozy nest. 301 00:20:32,465 --> 00:20:36,667 Barely a day old, they can't 302 00:20:36,669 --> 00:20:39,503 fly up to the entrance, so instead, 303 00:20:39,505 --> 00:20:42,573 they climb. 304 00:20:49,782 --> 00:20:52,883 They're equipped with strong claws just for this purpose. 305 00:21:12,505 --> 00:21:14,705 When they reach the opening, their first view 306 00:21:14,707 --> 00:21:17,942 of the outside world must come as quite a shock. 307 00:21:20,079 --> 00:21:21,746 It's a five-story drop. 308 00:21:24,817 --> 00:21:27,885 But somewhere down below, 309 00:21:27,887 --> 00:21:29,820 their mom is urging them 310 00:21:29,822 --> 00:21:32,323 to leave the only home they know 311 00:21:32,325 --> 00:21:36,627 so they can live the life they were born for, 312 00:21:36,629 --> 00:21:39,897 and that persuades them to do something 313 00:21:39,899 --> 00:21:43,267 that seems a little crazy. 314 00:22:08,594 --> 00:22:11,796 Some ducklings aren't as bold as others... 315 00:22:15,668 --> 00:22:18,736 And he who hesitates gets a push. 316 00:22:25,445 --> 00:22:27,445 Finally, 317 00:22:27,447 --> 00:22:29,213 driven by instinct and joined 318 00:22:29,215 --> 00:22:30,915 to one another by an inseparable bond, 319 00:22:30,917 --> 00:22:34,685 they all take the plunge. 320 00:22:52,605 --> 00:22:55,740 Once they've assembled on the ground, 321 00:22:55,742 --> 00:22:57,375 still following their mother's voice, 322 00:22:57,377 --> 00:23:02,113 they will make their way together through the woods 323 00:23:02,115 --> 00:23:07,451 to their new home on the water. 324 00:23:07,453 --> 00:23:12,289 As for the tree, it won't stand empty for long. 325 00:23:12,291 --> 00:23:17,495 Some other creature will take over the lease soon, 326 00:23:17,497 --> 00:23:21,499 perhaps a squirrel 327 00:23:21,501 --> 00:23:24,135 or a wild turkey, 328 00:23:24,137 --> 00:23:29,306 and our hooded merganser will be back in residence next year 329 00:23:29,308 --> 00:23:32,042 to bring another family into the world. 330 00:23:42,522 --> 00:23:44,955 Few animal homes could be simpler 331 00:23:44,957 --> 00:23:46,924 than the hooded merganser's. 332 00:23:49,662 --> 00:23:51,128 But here in this oak forest 333 00:23:51,130 --> 00:23:53,364 in the Ozark hills of southern Illinois, 334 00:23:53,366 --> 00:24:00,004 you'll find homes that are almost absurdly complicated. 335 00:24:00,006 --> 00:24:04,708 The builder uses whatever is at hand, 336 00:24:04,710 --> 00:24:07,344 and his tower of sticks and leaves is a reflection 337 00:24:07,346 --> 00:24:10,014 of the place where he lives. 338 00:24:15,188 --> 00:24:17,955 The architect behind this house 339 00:24:17,957 --> 00:24:21,926 is a little rodent with a good reason to build big. 340 00:24:23,996 --> 00:24:27,431 He's an eastern woodrat. 341 00:24:30,136 --> 00:24:32,336 He works nights, 342 00:24:32,338 --> 00:24:35,139 gathering building materials 343 00:24:35,141 --> 00:24:38,309 and fitting them into his grand edifice. 344 00:24:38,311 --> 00:24:40,311 It's a work in progress. 345 00:24:40,313 --> 00:24:43,347 As time goes on, 346 00:24:43,349 --> 00:24:47,218 it'll just keep getting bigger and bigger. 347 00:24:47,220 --> 00:24:50,788 Over the course of a lifetime, this woodrat's den 348 00:24:50,790 --> 00:24:53,891 will grow to an enormous size, 349 00:24:53,893 --> 00:24:58,496 with multiple chambers and plenty of storage space. 350 00:25:00,199 --> 00:25:03,367 So why does he need such a big house? 351 00:25:03,369 --> 00:25:04,602 Because the woodrat 352 00:25:04,604 --> 00:25:08,105 is an avid collector, which is why he's 353 00:25:08,107 --> 00:25:10,608 also known as a pack rat. 354 00:25:10,610 --> 00:25:13,677 He collects food, for instance -- 355 00:25:13,679 --> 00:25:16,447 seeds and nuts, 356 00:25:16,449 --> 00:25:18,182 fruit and leaves. 357 00:25:20,720 --> 00:25:23,621 What he doesn't eat 358 00:25:23,623 --> 00:25:25,489 he stores for the winter inside the den. 359 00:25:28,628 --> 00:25:34,231 But woodrats are looking for more than just food. 360 00:25:34,233 --> 00:25:37,801 They have a natural inclination, bordering on obsession, 361 00:25:37,803 --> 00:25:39,770 to scavenge their tiny territory 362 00:25:39,772 --> 00:25:41,906 for anything they find interesting 363 00:25:41,908 --> 00:25:44,575 and cart it all home. 364 00:25:50,249 --> 00:25:55,619 They seem especially attracted to the things we throw away -- 365 00:25:55,621 --> 00:25:58,255 toys, 366 00:25:58,257 --> 00:26:01,158 used shotgun shells, 367 00:26:01,160 --> 00:26:03,627 and anything shiny. 368 00:26:03,629 --> 00:26:06,330 They just love metal. 369 00:26:06,332 --> 00:26:10,200 But here's the mystery -- 370 00:26:10,202 --> 00:26:13,470 we have no idea why they're drawn to all this stuff. 371 00:26:13,472 --> 00:26:17,241 Most of it is of no practical use to them. 372 00:26:17,243 --> 00:26:19,610 It's not warm. They can't eat it. 373 00:26:19,612 --> 00:26:22,680 No matter. 374 00:26:22,682 --> 00:26:25,716 They're inveterate hoarders. 375 00:26:25,718 --> 00:26:30,521 It all gets incorporated into the walls of the house 376 00:26:30,523 --> 00:26:33,257 or socked away in a storage chamber. 377 00:26:35,595 --> 00:26:38,028 All this is a far cry 378 00:26:38,030 --> 00:26:39,296 from the compact 379 00:26:39,298 --> 00:26:42,466 and purely functional homes of most animals, 380 00:26:42,468 --> 00:26:44,702 but then, most animals lack 381 00:26:44,704 --> 00:26:47,972 the woodrat's predilection for junk. 382 00:26:52,244 --> 00:26:54,278 Sometimes, living in the right location 383 00:26:54,280 --> 00:26:59,650 is really all about having the right kind of neighbors. 384 00:27:03,255 --> 00:27:07,524 Here in the Chiricahua Mountains of southeast Arizona, 385 00:27:07,526 --> 00:27:09,360 there lives a little hummingbird 386 00:27:09,362 --> 00:27:13,397 that's taken that lesson to heart. 387 00:27:13,399 --> 00:27:16,367 I've come to learn more about it from biologist Harold Greeney. 388 00:27:16,369 --> 00:27:18,969 GREENEY: God, this is just beautiful. Wow. 389 00:27:18,971 --> 00:27:21,338 MORGAN: He's a hummingbird expert, 390 00:27:21,340 --> 00:27:24,642 and he knows how to find them by sight or by sound. 391 00:27:24,644 --> 00:27:28,946 GREENEY: One strategy is to just walk fairly directly 392 00:27:28,948 --> 00:27:33,384 from one spot to another and then just stop and listen. 393 00:27:33,386 --> 00:27:37,187 MORGAN: Harold has probably found more hummingbird nests 394 00:27:37,189 --> 00:27:38,589 than anyone on the planet. 395 00:27:38,591 --> 00:27:40,557 GREENEY: I think she kept on going. 396 00:27:40,559 --> 00:27:42,192 MORGAN: He has a special interest 397 00:27:42,194 --> 00:27:44,161 in the hummingbird that lives around here. 398 00:27:44,163 --> 00:27:45,696 It's called the black-chinned. 399 00:27:45,698 --> 00:27:47,364 -She's coming in. -Is she? 400 00:27:47,366 --> 00:27:48,766 GREENEY: She's gonna go. 401 00:27:48,768 --> 00:27:51,602 Now she's off to the right. Here she goes. 402 00:27:51,604 --> 00:27:53,504 And she just sat on the nest. 403 00:27:53,506 --> 00:27:55,005 -Is she on the nest? -She just went to the nest. 404 00:27:55,007 --> 00:27:56,573 MORGAN: Oh, no way. You spotted it. 405 00:27:56,575 --> 00:27:57,675 GREENEY: Yeah. Oh, there, 406 00:27:57,677 --> 00:27:59,176 she just came off the nest again. 407 00:27:59,178 --> 00:28:01,345 You don't even think the nest could fit there -- 408 00:28:01,347 --> 00:28:02,546 MORGAN: Oh, that's so cool. 409 00:28:02,548 --> 00:28:05,182 Wow, it's wrapped right around the branch. 410 00:28:05,184 --> 00:28:07,151 You would walk right past that. 411 00:28:07,153 --> 00:28:09,053 It's no bigger than a golf ball, really. 412 00:28:09,055 --> 00:28:10,454 GREENEY: Yeah. 413 00:28:10,456 --> 00:28:15,459 MORGAN: A bird so small making such a tiny, fragile home, 414 00:28:15,461 --> 00:28:18,529 it's easy to see how vulnerable it can be. 415 00:28:18,531 --> 00:28:21,498 And in fact, the black-chinned falls victim 416 00:28:21,500 --> 00:28:23,300 to an array of predators -- 417 00:28:23,302 --> 00:28:29,640 squirrels, snakes, and especially other birds. 418 00:28:29,642 --> 00:28:35,079 One of the worst offenders is the Mexican jay, 419 00:28:35,081 --> 00:28:37,548 which makes its own nest in these woods. 420 00:28:37,550 --> 00:28:40,718 Harold's good at spotting them, too. 421 00:28:40,720 --> 00:28:42,886 Do you see the nest right there in the fork of that tree? 422 00:28:42,888 --> 00:28:43,921 MORGAN: Oh, yes. 423 00:28:43,923 --> 00:28:47,024 GREENEY: She's on the nest right now. 424 00:28:47,026 --> 00:28:48,992 MORGAN: Yeah. Very nice. 425 00:28:48,994 --> 00:28:52,329 I'm distracted 'cause there's one there and there's one there, 426 00:28:52,331 --> 00:28:53,931 and they're both looking right down here, 427 00:28:53,933 --> 00:28:55,232 seeing exactly what's going on. 428 00:28:55,234 --> 00:28:57,234 GREENEY: Yeah, we're kind of close to their nest here, 429 00:28:57,236 --> 00:28:59,403 and, you know, they're coming to check us out and make sure 430 00:28:59,405 --> 00:29:01,105 we're not posing a threat. 431 00:29:01,107 --> 00:29:03,140 They're just like any other bird, when you get down to it. 432 00:29:03,142 --> 00:29:04,308 MORGAN: Right, right, 433 00:29:04,310 --> 00:29:05,976 but they are the enemy of the hummingbird. 434 00:29:05,978 --> 00:29:07,411 GREENEY: They are, in this case, 435 00:29:07,413 --> 00:29:08,746 the enemy of the hummingbird. 436 00:29:08,748 --> 00:29:11,548 MORGAN: And it's not hard to understand why. 437 00:29:11,550 --> 00:29:14,017 The jays have their own young to feed, 438 00:29:14,019 --> 00:29:18,822 and a hummingbird nest is so convenient. 439 00:29:18,824 --> 00:29:22,326 Harold himself shot this rare view 440 00:29:22,328 --> 00:29:26,396 of a jay feasting on a black-chinned's eggs. 441 00:29:38,310 --> 00:29:42,112 But some hummingbird nests are safer than others, 442 00:29:42,114 --> 00:29:46,216 and Harold has discovered why. 443 00:29:46,218 --> 00:29:51,555 GREENEY: Not too far away here is the hawk nest. 444 00:29:51,557 --> 00:29:53,690 MORGAN: It turns out the hummingbird 445 00:29:53,692 --> 00:29:55,893 doesn't build her nest just anywhere. 446 00:29:55,895 --> 00:29:58,529 Way easier to spot this one probably, eh? 447 00:29:58,531 --> 00:30:00,831 GREENEY: Yes, it's slightly larger. 448 00:30:00,833 --> 00:30:03,534 MORGAN: She often chooses a neighborhood where 449 00:30:03,536 --> 00:30:05,369 she can get help from her neighbors. 450 00:30:05,371 --> 00:30:08,205 Either Cooper's hawks 451 00:30:08,207 --> 00:30:10,274 or their close cousins, the goshawks, 452 00:30:10,276 --> 00:30:12,342 will serve the purpose. 453 00:30:12,344 --> 00:30:13,644 Oh, I see. 454 00:30:13,646 --> 00:30:15,679 This one's difficult to miss, that one. Wow. 455 00:30:15,681 --> 00:30:17,147 GREENEY: You could probably fit 456 00:30:17,149 --> 00:30:19,149 a hundred hummingbird nests inside there. 457 00:30:19,151 --> 00:30:20,951 And it's sort of, you know, 458 00:30:20,953 --> 00:30:23,120 at the upper level of this forest, 459 00:30:23,122 --> 00:30:24,888 watching over this whole area. 460 00:30:24,890 --> 00:30:28,559 MORGAN: Now, you'd think that a big killer like a hawk 461 00:30:28,561 --> 00:30:31,595 would make short work of a hummingbird. 462 00:30:31,597 --> 00:30:35,999 In fact, they don't bother with such small prey. 463 00:30:36,001 --> 00:30:39,169 GREENEY: For a bird this size, the morsel is so small. 464 00:30:39,171 --> 00:30:40,671 The challenge is so great. 465 00:30:40,673 --> 00:30:43,240 You burn more calories chasing a hummingbird 466 00:30:43,242 --> 00:30:44,842 than you get from eating it. 467 00:30:44,844 --> 00:30:46,910 You know, if you had to run up this hill 468 00:30:46,912 --> 00:30:48,712 to eat a Tic Tac and then go down 469 00:30:48,714 --> 00:30:50,280 and come back up to get a second one... 470 00:30:50,282 --> 00:30:52,282 MORGAN: I'd probably only do it seven or eight times. 471 00:30:52,284 --> 00:30:53,317 [Laughter] 472 00:30:55,921 --> 00:30:58,121 MORGAN: Jays, on the other hand, are perfect 473 00:30:58,123 --> 00:31:02,359 meal-sized prey for hawks, who attack them from above. 474 00:31:04,063 --> 00:31:07,431 The jays have only one defense -- 475 00:31:07,433 --> 00:31:11,201 being annoying. 476 00:31:11,203 --> 00:31:15,005 When a jay finds a hawk, it sounds the alarm. 477 00:31:16,575 --> 00:31:18,475 That alerts the other jays, 478 00:31:18,477 --> 00:31:21,245 and they all gather round to give the hawk what for, 479 00:31:21,247 --> 00:31:23,847 trying to drive it away. 480 00:31:28,120 --> 00:31:30,120 And sometimes it works. 481 00:31:32,858 --> 00:31:35,325 Because the hawks are such a big threat to jays, 482 00:31:35,327 --> 00:31:37,594 they've become the hummingbird's protector. 483 00:31:37,596 --> 00:31:41,765 As the old saying goes, 484 00:31:41,767 --> 00:31:46,136 the enemy of my enemy is my friend. 485 00:31:46,138 --> 00:31:50,140 Should we go up the hill and get a closer look? 486 00:31:50,142 --> 00:31:52,042 GREENEY: Oh, yeah, look at this. 487 00:31:52,044 --> 00:31:53,043 Spectacular. 488 00:31:53,045 --> 00:31:54,511 MORGAN: Whoa! Beautiful. 489 00:31:54,513 --> 00:31:57,180 Oh, fantastic! A great vantage point. 490 00:31:57,182 --> 00:31:58,849 GREENEY: And that's the vantage point 491 00:31:58,851 --> 00:32:00,217 that instills fear in the jays. 492 00:32:00,219 --> 00:32:02,452 So they normally forage at all levels in the forest -- 493 00:32:02,454 --> 00:32:04,087 on the ground, up into the canopy -- 494 00:32:04,089 --> 00:32:05,756 but when they know that hawk's there, 495 00:32:05,758 --> 00:32:08,692 they don't want to be underneath her because the way she hunts 496 00:32:08,694 --> 00:32:11,228 is to swoop down upon them. 497 00:32:11,230 --> 00:32:13,964 MORGAN: So from the hawk's position on high, 498 00:32:13,966 --> 00:32:16,833 you can imagine a kind of cone stretching down, 499 00:32:16,835 --> 00:32:20,904 taking in everything in the hawk's target area. 500 00:32:20,906 --> 00:32:25,108 For the jays, it's a no-fly zone. 501 00:32:25,110 --> 00:32:28,779 But for the hummingbirds, it's a safe haven, 502 00:32:28,781 --> 00:32:34,017 and their nests tend to be clustered inside that zone. 503 00:32:34,019 --> 00:32:36,553 The question is, 504 00:32:36,555 --> 00:32:40,057 do the hummingbirds really understand what's going on here? 505 00:32:40,059 --> 00:32:44,461 Do they seek out hawks when they look for a place to nest? 506 00:32:46,332 --> 00:32:49,700 Well, probably not. 507 00:32:49,702 --> 00:32:51,535 GREENEY: We know that the hummingbirds are 508 00:32:51,537 --> 00:32:53,503 very faithful to successful nest sites, 509 00:32:53,505 --> 00:32:56,273 so they build a nest, and if they are successful 510 00:32:56,275 --> 00:32:57,507 in fledging a brood, 511 00:32:57,509 --> 00:32:59,176 they'll come back and re-use that same site. 512 00:32:59,178 --> 00:33:00,444 MORGAN: They may have no idea 513 00:33:00,446 --> 00:33:02,212 that they're under the watchful eye of the hawks. 514 00:33:02,214 --> 00:33:05,182 GREENEY: That's actually my guess, yeah. 515 00:33:05,184 --> 00:33:08,485 MORGAN: For a black-chinned hummingbird, 516 00:33:08,487 --> 00:33:12,356 the trick is finding just the right place to live 517 00:33:12,358 --> 00:33:15,492 and the right neighbors to live near. 518 00:33:18,530 --> 00:33:22,032 But there's more to location than being in the right place. 519 00:33:22,034 --> 00:33:24,901 You also have to be there at the right time. 520 00:33:27,373 --> 00:33:30,507 Winter seems like the worst possible season 521 00:33:30,509 --> 00:33:34,544 for a bird to build a nest, 522 00:33:34,546 --> 00:33:39,950 but the cold doesn't stop these little songbirds. 523 00:33:39,952 --> 00:33:43,286 Gray jays maintain their territories all year round 524 00:33:43,288 --> 00:33:48,191 in the northernmost forests of North America 525 00:33:48,193 --> 00:33:49,459 and they breed 526 00:33:49,461 --> 00:33:51,995 in the dead of winter. 527 00:33:51,997 --> 00:33:54,398 Here in Canada's Algonquin Provincial Park, 528 00:33:54,400 --> 00:34:00,037 a pair of jays is working together on their nest. 529 00:34:00,039 --> 00:34:01,705 They've picked a spot 530 00:34:01,707 --> 00:34:04,908 that's exposed on the south side to catch as much of 531 00:34:04,910 --> 00:34:07,277 the weak winter sunlight as possible 532 00:34:07,279 --> 00:34:11,515 and is nestled under a branch to offer at least 533 00:34:11,517 --> 00:34:15,385 some protection against snowstorms. 534 00:34:39,378 --> 00:34:45,482 It's the female's job to incubate the eggs. 535 00:34:45,484 --> 00:34:47,918 She sits in the nest without a break 536 00:34:47,920 --> 00:34:49,786 for nearly three frigid weeks, 537 00:34:49,788 --> 00:34:55,158 doing her best to keep warm in subzero temperatures. 538 00:34:59,965 --> 00:35:03,333 It's up to her mate to keep her well-fed. 539 00:35:05,437 --> 00:35:11,308 There's precious little to eat in this frozen landscape, 540 00:35:11,310 --> 00:35:13,443 unless you plan ahead. 541 00:35:20,686 --> 00:35:23,220 During the fall, gray jays harvest 542 00:35:23,222 --> 00:35:26,556 the bounty of the forest and store it away 543 00:35:26,558 --> 00:35:30,494 in caches hidden in trees throughout their territory. 544 00:35:36,101 --> 00:35:39,102 Bugs and berries and bits of meat 545 00:35:39,104 --> 00:35:42,038 are tucked under flakes of bark. 546 00:35:42,040 --> 00:35:47,144 And not just any tree will do. 547 00:35:47,146 --> 00:35:51,481 Gray jays prefer black spruce for food storage. 548 00:35:51,483 --> 00:35:56,386 The bark is especially flaky, and its resin seems to do 549 00:35:56,388 --> 00:36:00,390 a better job of preserving perishable food. 550 00:36:00,392 --> 00:36:05,428 This pair of jays spend months creating a network 551 00:36:05,430 --> 00:36:09,432 of perhaps 10,000 food caches. 552 00:36:09,434 --> 00:36:11,635 That meant they had to collect 553 00:36:11,637 --> 00:36:14,804 and stash food hundreds of times every day 554 00:36:14,806 --> 00:36:17,974 and create a mental map of their territory 555 00:36:17,976 --> 00:36:21,144 to record where they put their groceries. 556 00:36:24,216 --> 00:36:26,616 Their memories are phenomenal. 557 00:36:26,618 --> 00:36:32,756 They manage to retrieve as much as 80% of the food they hide. 558 00:36:35,894 --> 00:36:37,928 The eggs will hatch in a few weeks, 559 00:36:37,930 --> 00:36:40,063 before spring has even begun. 560 00:36:40,065 --> 00:36:41,598 That will give the chicks 561 00:36:41,600 --> 00:36:45,936 a head start on growing up and developing brainpower. 562 00:36:45,938 --> 00:36:48,738 They'll need it when fall rolls around 563 00:36:48,740 --> 00:36:50,907 so they can find and store food 564 00:36:50,909 --> 00:36:55,378 and remember where they put it all. 565 00:36:57,649 --> 00:37:00,884 The Green Mountains of Vermont are home to 566 00:37:00,886 --> 00:37:03,587 the gray jay's much larger cousin, 567 00:37:03,589 --> 00:37:06,056 the common raven. 568 00:37:09,061 --> 00:37:11,061 In late winter, these granite cliffs 569 00:37:11,063 --> 00:37:15,432 echo with their rasping calls. 570 00:37:19,404 --> 00:37:21,571 Now, while the rest of the forest 571 00:37:21,573 --> 00:37:23,640 is still closed for the season, 572 00:37:23,642 --> 00:37:28,245 the ravens are starting a family. 573 00:37:28,247 --> 00:37:34,784 Ravens are big birds, and they build a big nest, 574 00:37:34,786 --> 00:37:39,256 woven from sticks a yard long. 575 00:37:39,258 --> 00:37:44,194 Because ravens are so secretive and cautious, 576 00:37:44,196 --> 00:37:46,429 their nests need to be hidden out of the way, 577 00:37:46,431 --> 00:37:49,299 like this one, 578 00:37:49,301 --> 00:37:53,370 in a crevice on a cliff face, 579 00:37:53,372 --> 00:37:56,640 with a rock overhang for protection. 580 00:37:56,642 --> 00:37:58,775 It's perfect for this family. 581 00:37:58,777 --> 00:38:01,478 In fact, the layout is so perfect, 582 00:38:01,480 --> 00:38:03,546 it's been used for thousands of years 583 00:38:03,548 --> 00:38:05,548 by countless generations of ravens. 584 00:38:05,550 --> 00:38:10,854 Once the chicks hatch, they grow fast. 585 00:38:10,856 --> 00:38:13,456 Within a few weeks, 586 00:38:13,458 --> 00:38:17,127 they're nearly as big as their parents, 587 00:38:17,129 --> 00:38:19,996 and they're ravenous. 588 00:38:22,501 --> 00:38:25,935 Both adults work overtime to keep food on the table 589 00:38:25,937 --> 00:38:27,704 for four hungry nestlings. 590 00:38:27,706 --> 00:38:31,141 Like jays, 591 00:38:31,143 --> 00:38:34,377 ravens store some food in hidden caches, 592 00:38:34,379 --> 00:38:38,715 but mostly they let the winter do their hunting for them, 593 00:38:38,717 --> 00:38:42,052 and winter is a cold-blooded killer. 594 00:38:47,292 --> 00:38:50,493 A dead deer can feed a lot of ravens. 595 00:38:50,495 --> 00:38:54,731 They're sociable birds, 596 00:38:54,733 --> 00:38:57,200 happy to share a big meal with other ravens, 597 00:38:57,202 --> 00:39:00,403 as well as a few neighbors. 598 00:39:02,941 --> 00:39:05,342 Their calls also alert less-welcome diners. 599 00:39:05,344 --> 00:39:08,345 Eagles are too big 600 00:39:08,347 --> 00:39:10,347 and too powerful to disinvite. 601 00:39:16,688 --> 00:39:19,155 But ravens are patient. 602 00:39:22,794 --> 00:39:25,628 Once the eagle has eaten its fill, 603 00:39:25,630 --> 00:39:27,731 there's still plenty left. 604 00:39:31,370 --> 00:39:35,739 Some of the meat they'll eat on the spot. 605 00:39:35,741 --> 00:39:38,942 But for these working parents, the main priority 606 00:39:38,944 --> 00:39:41,745 is to bring food back to the nest. 607 00:39:41,747 --> 00:39:44,881 Their chicks are in a hurry to grow up. 608 00:39:47,719 --> 00:39:50,587 Before long, it'll be their turn to make their homes 609 00:39:50,589 --> 00:39:54,090 in these ancient granite cliffs. 610 00:40:02,834 --> 00:40:05,969 Many mammals do what jays and ravens do -- 611 00:40:05,971 --> 00:40:08,838 start a family during the winter. 612 00:40:08,840 --> 00:40:10,039 But to succeed, 613 00:40:10,041 --> 00:40:13,410 they need the right home in the right place. 614 00:40:13,412 --> 00:40:18,415 I've been studying bears for more than 20 years. 615 00:40:18,417 --> 00:40:20,850 My own work is based in the Cascade Mountains 616 00:40:20,852 --> 00:40:23,520 of Washington State and up in Alaska, 617 00:40:23,522 --> 00:40:27,557 but black bears are making a comeback 618 00:40:27,559 --> 00:40:31,428 all over the eastern United States, 619 00:40:31,430 --> 00:40:33,630 so I've come to Maryland's Allegheny Mountains 620 00:40:33,632 --> 00:40:35,398 to learn more about how these bears 621 00:40:35,400 --> 00:40:37,767 make their homes and where. 622 00:40:40,472 --> 00:40:43,840 A bear's home is really a seasonal thing, 623 00:40:43,842 --> 00:40:45,442 a hideaway where it can hibernate 624 00:40:45,444 --> 00:40:48,711 during the long winter months, 625 00:40:48,713 --> 00:40:52,115 and for a female, it's much more than that. 626 00:40:52,117 --> 00:40:53,149 [Chuckling] Oh. 627 00:40:53,151 --> 00:40:54,451 Look at that. 628 00:40:54,453 --> 00:40:57,854 I love getting into the mind of a bear 629 00:40:57,856 --> 00:40:59,956 and wondering what they're thinking. 630 00:40:59,958 --> 00:41:02,058 So imagine a female bear in November 631 00:41:02,060 --> 00:41:04,627 is looking for a place that she's going to spend 632 00:41:04,629 --> 00:41:05,895 the next six months. 633 00:41:05,897 --> 00:41:08,898 So she's thinking about it needs to be isolated 634 00:41:08,900 --> 00:41:10,366 and insulated and safe 635 00:41:10,368 --> 00:41:12,869 and maybe somewhere that's near food and water. 636 00:41:12,871 --> 00:41:15,338 In the days just before she goes into her den, 637 00:41:15,340 --> 00:41:17,340 she'll be drinking gallons of water 638 00:41:17,342 --> 00:41:19,175 just to help her process the fat 639 00:41:19,177 --> 00:41:21,144 so that she can survive the winter. 640 00:41:21,146 --> 00:41:23,480 So she's got an awful lot on her mind 641 00:41:23,482 --> 00:41:25,982 as she's trying to select the best home, 642 00:41:25,984 --> 00:41:28,351 but this would be perfect. 643 00:41:28,353 --> 00:41:31,488 This den is empty now, but last year, 644 00:41:31,490 --> 00:41:34,357 for one bear, it was a very special place. 645 00:41:34,359 --> 00:41:37,560 Perfect. 646 00:41:37,562 --> 00:41:42,966 Completely dry and sheltered in here. 647 00:41:42,968 --> 00:41:45,068 This is where it all happens. 648 00:41:50,509 --> 00:41:53,443 She comes into this den alone 649 00:41:53,445 --> 00:41:56,412 and she stops eating, she stops drinking. 650 00:41:56,414 --> 00:41:58,882 Her heartbeats drop to about eight per minute, 651 00:41:58,884 --> 00:42:02,085 her respiration, breathing, down to about eight per minute, 652 00:42:02,087 --> 00:42:04,787 and she's alone. 653 00:42:04,789 --> 00:42:07,690 But then something even more surprising happens. 654 00:42:07,692 --> 00:42:10,460 In February, she gives birth inside this den, 655 00:42:10,462 --> 00:42:13,029 half asleep, to maybe four or three cubs, 656 00:42:13,031 --> 00:42:16,666 and then two months later, they follow the light 657 00:42:16,668 --> 00:42:20,603 at the end of the tunnel and shadow mom as she leaves 658 00:42:20,605 --> 00:42:23,673 into this big, wide world of adventure. 659 00:42:23,675 --> 00:42:27,010 What a way to start life. 660 00:42:33,952 --> 00:42:39,122 Black bears here in Maryland are reproducing at a rapid rate. 661 00:42:39,124 --> 00:42:44,761 In some areas, their population has doubled in the past decade. 662 00:42:44,763 --> 00:42:49,432 That means they often make their homes near where people live, 663 00:42:49,434 --> 00:42:53,369 so the state has an interest in keeping a close eye 664 00:42:53,371 --> 00:42:56,439 on the bears and locating their dens. 665 00:43:02,314 --> 00:43:06,349 It's the end of March in these snowy woods. 666 00:43:06,351 --> 00:43:09,052 I've met up with Harry Spiker and his team 667 00:43:09,054 --> 00:43:12,188 from the Maryland Department of Natural Resources. 668 00:43:12,190 --> 00:43:14,490 SPIKER: There you go. 669 00:43:14,492 --> 00:43:15,892 MORGAN: They're checking on 670 00:43:15,894 --> 00:43:18,094 the health and welfare of the local bears. 671 00:43:18,096 --> 00:43:19,929 We've got a short walk in? 672 00:43:19,931 --> 00:43:21,764 SPIKER: About a half-mile. 673 00:43:21,766 --> 00:43:25,468 MORGAN: We're planning our approach to another den, 674 00:43:25,470 --> 00:43:28,638 one where the residents are still at home. 675 00:43:28,640 --> 00:43:31,674 She's right up there, up pretty high on the rocks. 676 00:43:37,449 --> 00:43:39,349 MORGAN: [Whispering] They're trying to figure out 677 00:43:39,351 --> 00:43:40,383 the best route to the cave, 678 00:43:40,385 --> 00:43:41,618 and we have to be very quiet 679 00:43:41,620 --> 00:43:43,620 because we don't want to disturb this female. 680 00:43:43,622 --> 00:43:45,321 You'll hit rock wall. 681 00:43:45,323 --> 00:43:47,323 Skirt around. 682 00:43:47,325 --> 00:43:51,127 MORGAN: You can see why a bear would be drawn to this area. 683 00:43:51,129 --> 00:43:53,463 We're surrounded by these giant boulders, 684 00:43:53,465 --> 00:43:55,898 and there are these dark holes between them 685 00:43:55,900 --> 00:43:57,667 that look perfect for denning. 686 00:43:57,669 --> 00:44:01,170 And you can also see Harry's military background coming out. 687 00:44:03,975 --> 00:44:06,075 He's going in first, 688 00:44:06,077 --> 00:44:08,645 and if he can't dart the bear and she decides to exit, 689 00:44:08,647 --> 00:44:10,146 then Georgia here is the backup. 690 00:44:10,148 --> 00:44:12,649 She can hopefully dart the bear as it comes through. 691 00:44:29,501 --> 00:44:32,035 [Pop] 692 00:44:32,037 --> 00:44:35,972 With the bear safely tranquilized, 693 00:44:35,974 --> 00:44:38,408 I can take a look inside her den. 694 00:44:38,410 --> 00:44:42,045 Oh, it's a very tight space. 695 00:44:42,047 --> 00:44:46,349 The perfect home, nice and secure. 696 00:44:49,688 --> 00:44:53,189 Oh, wow. 697 00:44:53,191 --> 00:44:54,824 Oh, four cubs. 698 00:44:54,826 --> 00:44:57,026 She has four. 699 00:44:57,028 --> 00:44:58,995 [Laugh] 700 00:44:58,997 --> 00:45:00,596 Look at that. 701 00:45:00,598 --> 00:45:02,999 There's four of them, four cubs in here, 702 00:45:03,001 --> 00:45:04,200 and a big female. 703 00:45:04,202 --> 00:45:06,869 She looks huge, actually, just squashed in here, 704 00:45:06,871 --> 00:45:08,104 a tiny little space, 705 00:45:08,106 --> 00:45:10,673 a really narrow little section of the cave, 706 00:45:10,675 --> 00:45:12,842 but it makes it a perfect bear home 707 00:45:12,844 --> 00:45:14,744 because it's secure, it's dry. 708 00:45:14,746 --> 00:45:16,546 She's pulled in all these leaves. 709 00:45:16,548 --> 00:45:18,481 Look at all these rhododendron leaves 710 00:45:18,483 --> 00:45:20,016 that she's snipped from outside 711 00:45:20,018 --> 00:45:21,818 and pulled in here to make a bed. 712 00:45:21,820 --> 00:45:23,319 A perfect place, though. 713 00:45:23,321 --> 00:45:25,354 Really healthy female and with four cubs. 714 00:45:25,356 --> 00:45:26,622 That's a really good sign. 715 00:45:26,624 --> 00:45:29,592 Okay, we're just pulling out the cubs 716 00:45:29,594 --> 00:45:32,962 so that we can weigh them and measure them. 717 00:45:32,964 --> 00:45:35,798 It's okay, little guy. 718 00:45:35,800 --> 00:45:36,866 Okay, I got two here. 719 00:45:36,868 --> 00:45:38,167 SPIKER: Coming out over my shoulder. 720 00:45:38,169 --> 00:45:40,036 MORGAN: Another one there. 721 00:45:40,038 --> 00:45:41,637 MAN: Yep, it's coming. 722 00:45:41,639 --> 00:45:43,306 MORGAN: There you go, little guy. 723 00:45:45,410 --> 00:45:48,077 GEORGIA: Seven on the dot, seven pounds. 724 00:45:48,079 --> 00:45:52,949 MORGAN: Outside the den, their mom doesn't look so big. 725 00:45:52,951 --> 00:45:55,017 She's only about a hundred pounds, 726 00:45:55,019 --> 00:45:56,152 but she's a beauty. 727 00:45:56,154 --> 00:45:57,587 She looks in really good shape. 728 00:45:57,589 --> 00:45:59,155 SPIKER: Oh, she is in great shape. 729 00:45:59,157 --> 00:46:02,291 Her teeth look great. 730 00:46:02,293 --> 00:46:06,996 MORGAN: Quite a young bear, by the looks of it. 731 00:46:06,998 --> 00:46:09,298 Incredible to see this this thick mat of wool under there. 732 00:46:09,300 --> 00:46:11,100 -Oh, absolutely. -That's what it's all about. 733 00:46:11,102 --> 00:46:12,168 She'd be lost without it. 734 00:46:12,170 --> 00:46:14,203 You feeling good about her and the cubs? 735 00:46:14,205 --> 00:46:16,005 SPIKER: Real good, yeah, very good. 736 00:46:16,007 --> 00:46:19,776 MORGAN: While the team does 737 00:46:19,778 --> 00:46:21,244 a full work-up on the female... 738 00:46:21,246 --> 00:46:22,378 Look at that. 739 00:46:22,380 --> 00:46:24,547 I get a chance to enjoy a moment 740 00:46:24,549 --> 00:46:26,482 I've always dreamed off. 741 00:46:26,484 --> 00:46:29,118 [Sigh] 742 00:46:29,120 --> 00:46:31,120 Hey. Hey. 743 00:46:31,122 --> 00:46:34,357 You guys are perfect, aren't you? 744 00:46:34,359 --> 00:46:36,459 Oh, this has got to be 745 00:46:36,461 --> 00:46:41,063 one of the most memorable experiences of my life. 746 00:46:41,065 --> 00:46:44,934 Just look at those guys. Four of them. 747 00:46:44,936 --> 00:46:47,036 And we've got two of these guys here. 748 00:46:47,038 --> 00:46:48,771 As soon as you put them in your coat, 749 00:46:48,773 --> 00:46:50,740 they just want to feel comfortable and warm. 750 00:46:50,742 --> 00:46:54,410 They kind of chill out, and I guess it must feel like 751 00:46:54,412 --> 00:46:58,181 they're close to their mom, like they are in that cave. 752 00:46:58,183 --> 00:46:59,582 It's the first time 753 00:46:59,584 --> 00:47:02,185 these guys have seen daylight, and I'm definitely 754 00:47:02,187 --> 00:47:04,387 the first human being that they've seen. 755 00:47:04,389 --> 00:47:07,523 That's an incredible thought. 756 00:47:07,525 --> 00:47:10,893 It's just the biggest honor 757 00:47:10,895 --> 00:47:13,462 playing surrogate mom for a few minutes. 758 00:47:19,771 --> 00:47:22,038 They're lucky little bears, 759 00:47:22,040 --> 00:47:25,074 with a healthy mom and a comfy den 760 00:47:25,076 --> 00:47:27,910 in just the right location. 761 00:47:36,387 --> 00:47:40,456 Back on the pond, winter has worked its magic, 762 00:47:40,458 --> 00:47:44,227 radically transforming the beavers' world. 763 00:47:44,229 --> 00:47:48,731 Their pond is nearly frozen over... 764 00:47:54,005 --> 00:48:00,543 And the lodge is camouflaged under a mantle of white. 765 00:48:00,545 --> 00:48:02,578 [Howling wind] 766 00:48:02,580 --> 00:48:05,181 All around, the landscape may be buffeted 767 00:48:05,183 --> 00:48:06,716 by 60-mile-an-hour winds 768 00:48:06,718 --> 00:48:11,454 and chilled to minus-30 degrees. 769 00:48:11,456 --> 00:48:14,857 Many of these animals are grazers, 770 00:48:14,859 --> 00:48:17,059 so they're homeless. 771 00:48:17,061 --> 00:48:21,931 They have to stay on the move, regardless of the weather, 772 00:48:21,933 --> 00:48:27,603 scratching out their survival from beneath the snow. 773 00:48:27,605 --> 00:48:30,039 As a result, they're exposed to the worst 774 00:48:30,041 --> 00:48:32,441 that winter can dish out 775 00:48:32,443 --> 00:48:37,680 and they depend upon their coats to keep out the cold. 776 00:48:37,682 --> 00:48:41,817 The snow can pile up three or four feet 777 00:48:41,819 --> 00:48:45,488 and everything gets a coating of ice -- 778 00:48:45,490 --> 00:48:50,259 everything. 779 00:48:50,261 --> 00:48:53,462 For the beavers, 780 00:48:53,464 --> 00:48:56,933 life couldn't be more different. 781 00:48:56,935 --> 00:49:01,704 With the mud and the lodge walls frozen hard as concrete, 782 00:49:01,706 --> 00:49:05,641 their home is impervious to wind and snow. 783 00:49:05,643 --> 00:49:10,780 The ice on their pond may be a foot thick, 784 00:49:10,782 --> 00:49:13,482 but thanks to the beavers' efforts, 785 00:49:13,484 --> 00:49:15,518 the water is deep enough that it won't freeze 786 00:49:15,520 --> 00:49:19,522 all the way to the bottom, 787 00:49:19,524 --> 00:49:23,693 so there's plenty of room to swim. 788 00:49:29,767 --> 00:49:34,236 In the lodge, winter is five months of family time, 789 00:49:34,238 --> 00:49:37,039 and this family has a full house, 790 00:49:37,041 --> 00:49:39,141 with two parents, 791 00:49:39,143 --> 00:49:41,510 a pair of adolescents born last year, 792 00:49:41,512 --> 00:49:44,246 and by late winter, 793 00:49:44,248 --> 00:49:48,050 newborn kits. 794 00:49:48,052 --> 00:49:52,121 With all that shared body heat, the temperature in here 795 00:49:52,123 --> 00:49:56,459 may be 60 degrees warmer than outside. 796 00:49:56,461 --> 00:50:00,863 The beavers' larder is near their underwater entrance, 797 00:50:00,865 --> 00:50:04,567 maybe a thousand pounds of tree limbs and logs. 798 00:50:04,569 --> 00:50:08,371 They can just pop out the front door, 799 00:50:08,373 --> 00:50:11,907 grab a meal, and swim back in to feed. 800 00:50:11,909 --> 00:50:17,580 Here in the darkness, in the safety of their lodge, 801 00:50:17,582 --> 00:50:20,182 they spend most of their waking hours 802 00:50:20,184 --> 00:50:22,718 reinforcing family bonds by grooming 803 00:50:22,720 --> 00:50:25,154 and eating together. 804 00:50:28,359 --> 00:50:31,627 For kits, like human kids, 805 00:50:31,629 --> 00:50:34,196 mealtime can turn into a game. 806 00:50:46,511 --> 00:50:49,111 Much of a winter's day is passed 807 00:50:49,113 --> 00:50:50,913 just sleeping. 808 00:50:57,722 --> 00:51:00,656 They've earned a rest. 809 00:51:00,658 --> 00:51:04,693 After all, they worked hard last summer, 810 00:51:04,695 --> 00:51:06,095 engineering a new habitat 811 00:51:06,097 --> 00:51:11,233 and winterizing their lodge. 812 00:51:11,235 --> 00:51:16,272 Now they get to enjoy all the creature comforts. 813 00:51:24,015 --> 00:51:27,683 The beavers have created what every animal looks for 814 00:51:27,685 --> 00:51:30,052 in a home. 815 00:51:34,459 --> 00:51:36,525 Oh, wow. 816 00:51:36,527 --> 00:51:39,929 It's a safe haven, a place that's warm and secure, 817 00:51:39,931 --> 00:51:43,199 a place where they can give their young ones 818 00:51:43,201 --> 00:51:46,035 the very best start in life. 819 00:51:54,811 --> 00:51:57,079 MORGAN: Their nature's architects and engineers, 820 00:51:57,081 --> 00:52:00,850 crafting homes of spectacular design, 821 00:52:00,852 --> 00:52:04,153 and every one of these fantastic creations tells a story. 822 00:52:04,155 --> 00:52:06,355 While many homeowners seek privacy, 823 00:52:06,357 --> 00:52:08,524 others band together. 824 00:52:08,526 --> 00:52:12,995 Competition and cooperation push and pull on village life, 825 00:52:12,997 --> 00:52:15,865 giving rise to complex societies where millions of citizens 826 00:52:15,867 --> 00:52:19,101 build a metropolis like nothing else on earth. 827 00:52:57,241 --> 00:53:00,442 To learn more about what you've seen on this "Nature" program, 828 00:53:00,444 --> 00:53:00,442 visit pbs.org.