1 00:00:08,833 --> 00:00:11,666 {\an1}THURMAN: It's your first day in the world, 2 00:00:11,700 --> 00:00:15,166 {\an1}your first step into a vast 3 00:00:15,200 --> 00:00:16,933 {\an1}and daunting landscape... 4 00:00:20,000 --> 00:00:23,266 {\an1}...full of possibilities... 5 00:00:23,300 --> 00:00:26,000 wonder... 6 00:00:26,033 --> 00:00:27,500 and peril. 7 00:00:27,533 --> 00:00:29,966 [ Wind whistling ] 8 00:00:30,000 --> 00:00:34,166 You've just been born in the Rockies, 9 00:00:34,200 --> 00:00:39,266 an untamed wilderness in the heart of North America. 10 00:00:39,300 --> 00:00:42,133 {\an1}And you have much to learn. 11 00:00:42,166 --> 00:00:44,933 Each new challenge will test your resolve. 12 00:00:47,833 --> 00:00:50,800 Every new opportunity will hone your skills. 13 00:00:50,833 --> 00:00:55,266 {\an8}♪♪♪ 14 00:00:55,300 --> 00:00:58,400 {\an1}Above all, you'll need to stick close to Mother. 15 00:00:58,433 --> 00:01:02,966 {\an1}Only her care and vigilance can protect you... 16 00:01:03,000 --> 00:01:05,733 {\an1}and prepare you for a life 17 00:01:05,766 --> 00:01:08,833 {\an1}in the wilds of the Rockies. 18 00:01:11,000 --> 00:01:13,466 {\an8}♪♪♪ 19 00:01:13,500 --> 00:01:20,933 {\an8}♪♪♪ 20 00:01:20,966 --> 00:01:28,966 {\an8}♪♪♪ 21 00:01:47,566 --> 00:01:49,400 {\an8}[ Wind whistling ] 22 00:01:54,933 --> 00:01:56,900 {\an7}THURMAN: It's late February 23 00:01:56,933 --> 00:01:59,833 {\an8}in the high deserts of central New Mexico. 24 00:02:02,333 --> 00:02:06,766 {\an7}Evening temperatures can drop well below freezing, 25 00:02:06,800 --> 00:02:10,666 {\an1}locking these Sandhill cranes in a layer of ice. 26 00:02:18,200 --> 00:02:20,866 Those that have freed themselves 27 00:02:20,900 --> 00:02:22,800 must walk gingerly. 28 00:02:22,833 --> 00:02:24,800 [ Ice cracking ] 29 00:02:36,700 --> 00:02:39,400 {\an1}They're huddled together in this shallow wetland 30 00:02:39,433 --> 00:02:42,100 {\an1}for a simple reason... 31 00:02:42,133 --> 00:02:43,866 security. 32 00:02:45,800 --> 00:02:48,133 {\an1}Coyotes are patrolling the shoreline... 33 00:02:50,366 --> 00:02:52,700 {\an1}...looking for any openings. 34 00:02:52,733 --> 00:02:56,000 {\an8}♪♪♪ 35 00:02:56,033 --> 00:02:57,666 [ Warbles ] 36 00:02:57,700 --> 00:03:00,366 {\an1}But there are far too many eyes, 37 00:03:00,400 --> 00:03:02,666 and the cranes are already awake. 38 00:03:02,700 --> 00:03:08,466 {\an8}♪♪♪ 39 00:03:08,500 --> 00:03:12,000 About 20,000 cranes over-winter here, 40 00:03:12,033 --> 00:03:16,166 {\an1}mostly family groups made up of couples and their young. 41 00:03:17,733 --> 00:03:21,033 It may not seem like the most romantic setting, 42 00:03:21,066 --> 00:03:22,866 huddled together with a few hundred 43 00:03:22,900 --> 00:03:25,866 {\an1}of your closest relatives. 44 00:03:25,900 --> 00:03:28,266 But make no mistake. 45 00:03:28,300 --> 00:03:31,900 This is a love story. 46 00:03:31,933 --> 00:03:35,566 {\an1}In the still of the morning, couples call to each other... 47 00:03:35,600 --> 00:03:36,933 [ Cranes calling ] 48 00:03:36,966 --> 00:03:40,733 keeping track of their lifelong mates. 49 00:03:40,766 --> 00:03:43,500 {\an1}Some have been together for more than a decade. 50 00:03:43,533 --> 00:03:49,700 {\an8}♪♪♪ 51 00:03:49,733 --> 00:03:54,166 {\an1}But the end of winter marks the beginning of a new journey. 52 00:03:56,533 --> 00:04:01,266 {\an1}Cranes signal with their heads that it's time to take flight. 53 00:04:01,300 --> 00:04:08,400 {\an8}♪♪♪ 54 00:04:08,433 --> 00:04:13,100 {\an1}One by one, they launch awkwardly into the sky. 55 00:04:18,300 --> 00:04:20,233 Countless generations before them 56 00:04:20,266 --> 00:04:24,300 have undertaken this same journey... 57 00:04:24,333 --> 00:04:28,933 {\an1}an unbroken migration that has lasted thousands of years. 58 00:04:32,333 --> 00:04:33,633 {\an1}They are headed north, 59 00:04:33,666 --> 00:04:37,533 {\an1}across the sandstone cliffs of New Mexico 60 00:04:37,566 --> 00:04:41,633 and into the heart of the Rocky Mountains. 61 00:04:44,833 --> 00:04:48,733 {\an1}The Rocky Mountains stretch some 2,000 miles, 62 00:04:48,766 --> 00:04:52,566 forming the backbone of North America. 63 00:04:52,600 --> 00:04:56,700 {\an1}From central New Mexico, the Rockies continue northward 64 00:04:56,733 --> 00:05:01,866 {\an1}across six western states to the northern edge of Canada, 65 00:05:01,900 --> 00:05:05,733 encompassing at least 100 different mountain ranges 66 00:05:05,766 --> 00:05:09,133 {\an1}and dozens of unique habitats, 67 00:05:09,166 --> 00:05:11,933 {\an1}from shifting sand dunes 68 00:05:11,966 --> 00:05:14,000 {\an1}to deep river valleys. 69 00:05:16,500 --> 00:05:19,800 Each providing a home for countless animal families 70 00:05:19,833 --> 00:05:22,366 {\an1}on the verge of a new beginning. 71 00:05:22,400 --> 00:05:29,933 {\an8}♪♪♪ 72 00:05:29,966 --> 00:05:37,466 {\an8}♪♪♪ 73 00:05:37,500 --> 00:05:41,366 {\an1}And just as they have done for millions of years, 74 00:05:41,400 --> 00:05:46,000 {\an1}the Rockies begin to shed the months of frozen dormancy... 75 00:05:47,500 --> 00:05:49,433 {\an1}...and prepares to welcome 76 00:05:49,466 --> 00:05:52,333 the next generation into their midst. 77 00:05:52,366 --> 00:05:58,166 {\an8}♪♪♪ 78 00:05:58,200 --> 00:06:01,000 {\an1}Weeks after leaving New Mexico, 79 00:06:01,033 --> 00:06:03,766 {\an1}Sandhill cranes arrive to their natal range 80 00:06:03,800 --> 00:06:06,066 {\an1}in Yellowstone Valley. 81 00:06:06,100 --> 00:06:08,066 [ Cranes calling ] 82 00:06:19,800 --> 00:06:24,833 {\an1}When it comes to settling down, cranes prize personal space. 83 00:06:27,033 --> 00:06:30,433 {\an1}This is a call to anyone in earshot... 84 00:06:30,466 --> 00:06:33,266 "This spot is ours." 85 00:06:34,333 --> 00:06:37,066 Having flown here with his parents, 86 00:06:37,100 --> 00:06:40,200 {\an1}the yearling tags along. 87 00:06:40,233 --> 00:06:45,300 {\an1}But now it's time for Mom and Dad to renew their vows... 88 00:06:45,333 --> 00:06:47,133 with a dance. 89 00:06:47,166 --> 00:06:53,833 {\an8}♪♪♪ 90 00:06:53,866 --> 00:06:56,600 The youngster watches his parents intently... 91 00:06:59,833 --> 00:07:01,733 {\an1}...learning the very moves 92 00:07:01,766 --> 00:07:05,433 {\an1}he will one day employ to woo his mate. 93 00:07:05,466 --> 00:07:13,466 {\an8}♪♪♪ 94 00:07:14,166 --> 00:07:22,166 {\an8}♪♪♪ 95 00:07:22,900 --> 00:07:30,900 {\an8}♪♪♪ 96 00:07:31,600 --> 00:07:37,566 {\an1}At last, all this extravagance culminates in one final move. 97 00:07:53,933 --> 00:07:57,800 And now all they have to do is wait. 98 00:07:57,833 --> 00:08:05,233 {\an8}♪♪♪ 99 00:08:05,266 --> 00:08:08,166 Nestled in the heart of the Rocky Mountains, 100 00:08:08,200 --> 00:08:11,800 {\an1}Yellowstone is the world's first national park... 101 00:08:14,000 --> 00:08:17,966 {\an1}...and the largest nearly intact temperate ecosystem on Earth. 102 00:08:20,866 --> 00:08:23,533 Spring is the time when new families 103 00:08:23,566 --> 00:08:27,166 {\an1}are taking their first tentative steps into the world. 104 00:08:27,200 --> 00:08:34,500 {\an8}♪♪♪ 105 00:08:34,533 --> 00:08:39,100 {\an1}For many young, it's their first big adventure aboveground. 106 00:08:39,133 --> 00:08:42,466 {\an1}It's a time to play... 107 00:08:42,500 --> 00:08:44,933 explore... 108 00:08:44,966 --> 00:08:47,333 {\an1}and torment your siblings. 109 00:08:49,733 --> 00:08:53,633 And in some cases, test your mother's patience. 110 00:08:56,700 --> 00:08:59,233 {\an1}Play is an essential part of childhood... 111 00:08:59,266 --> 00:09:04,500 {\an8}♪♪♪ 112 00:09:04,533 --> 00:09:07,800 {\an1}...and one that, sadly, will not last forever. 113 00:09:12,133 --> 00:09:16,733 {\an1}For this playful grizzly mom and her 3-year-old cub, 114 00:09:16,766 --> 00:09:19,266 {\an1}this will be their last spring together. 115 00:09:19,300 --> 00:09:25,733 {\an8}♪♪♪ 116 00:09:25,766 --> 00:09:30,233 {\an1}For some, this time of year marks the end of a relationship, 117 00:09:30,266 --> 00:09:33,466 while for others, it's the beginning of a new one. 118 00:09:33,500 --> 00:09:38,633 {\an8}♪♪♪ 119 00:09:38,666 --> 00:09:43,066 {\an1}In the open grasslands of Yellowstone, 120 00:09:43,100 --> 00:09:45,366 {\an1}a mother bison is giving birth. 121 00:09:45,400 --> 00:09:47,033 {\an1}[ Bison grunting softly ] 122 00:09:47,066 --> 00:09:49,900 [ Birds chirping ] 123 00:10:00,233 --> 00:10:04,466 {\an1}Mom frees her calf from the membrane that entangles it. 124 00:10:04,500 --> 00:10:08,333 For her, this is love at first sight. 125 00:10:08,366 --> 00:10:12,066 {\an1}The same hormones that surge through a human mother's brain 126 00:10:12,100 --> 00:10:14,466 {\an1}now surge through hers. 127 00:10:16,400 --> 00:10:18,033 {\an1}For the next several months, 128 00:10:18,066 --> 00:10:21,666 {\an1}this calf will be the singular focus of her life... 129 00:10:21,700 --> 00:10:24,700 {\an1}the one thing she will nurture and protect. 130 00:10:31,333 --> 00:10:34,166 {\an1}Yellowstone is slowly awakening, 131 00:10:34,200 --> 00:10:37,200 puling itself out from under winter's grip. 132 00:10:47,866 --> 00:10:50,166 {\an1}It's a treacherous time, 133 00:10:50,200 --> 00:10:53,233 {\an1}as the ground is melting away beneath them. 134 00:10:55,000 --> 00:10:58,433 And for a newborn still finding its footing, 135 00:10:58,466 --> 00:11:01,466 {\an1}it's easy to get knocked off course. 136 00:11:07,833 --> 00:11:10,333 {\an1}This is a deadly situation. 137 00:11:11,866 --> 00:11:16,966 {\an1}Many bison, much older than this calf, have met their ends here. 138 00:11:20,300 --> 00:11:23,766 But there is little his mother can do. 139 00:11:23,800 --> 00:11:25,433 He's on his own now. 140 00:11:39,600 --> 00:11:44,166 {\an1}Although he's only days old, he must find the strength... 141 00:11:44,200 --> 00:11:47,300 {\an1}[ Bison grunting softly ] 142 00:11:47,333 --> 00:11:50,066 {\an1}...the will to survive, 143 00:11:50,100 --> 00:11:52,966 {\an1}to fight with every muscle in his body. 144 00:11:55,166 --> 00:11:58,400 {\an1}To fight or to die trying. 145 00:12:19,066 --> 00:12:21,633 The relieved mother hurries to greet him... 146 00:12:23,333 --> 00:12:27,233 {\an1}...licking him dry, as she did the day he was first born. 147 00:12:30,666 --> 00:12:32,400 He was fortunate. 148 00:12:32,433 --> 00:12:34,166 {\an1}But in the months ahead, 149 00:12:34,200 --> 00:12:38,166 {\an1}the Rockies will continue to test our calf's resolve. 150 00:12:38,200 --> 00:12:46,200 {\an8}♪♪♪ 151 00:12:47,100 --> 00:12:50,933 {\an1}Some 55 to 80 million years ago, 152 00:12:50,966 --> 00:12:54,300 an intense period of plate tectonic activity 153 00:12:54,333 --> 00:12:58,233 {\an1}reshaped the western half of North America 154 00:12:58,266 --> 00:13:02,033 and gave birth to the Rocky Mountains. 155 00:13:02,066 --> 00:13:03,433 [ Wind whistling ] 156 00:13:03,466 --> 00:13:07,266 {\an1}This massive wall of mountains has an enormous influence 157 00:13:07,300 --> 00:13:10,166 on weather patterns across North America. 158 00:13:13,066 --> 00:13:15,900 {\an1}Air currents moving eastward from the Pacific 159 00:13:15,933 --> 00:13:18,233 {\an1}are disrupted by the Rockies... 160 00:13:18,266 --> 00:13:22,633 {\an8}♪♪♪ 161 00:13:22,666 --> 00:13:24,900 {\an1}...generating massive cyclones 162 00:13:24,933 --> 00:13:27,733 {\an1}across the Great Plains of North America. 163 00:13:27,766 --> 00:13:33,600 {\an8}♪♪♪ 164 00:13:33,633 --> 00:13:39,500 {\an8}♪♪♪ 165 00:13:39,533 --> 00:13:43,233 {\an1}And just as the Rockies have transformed the land, 166 00:13:43,266 --> 00:13:46,833 they have also shaped the animals that call it home. 167 00:14:01,900 --> 00:14:05,500 {\an1}Mountain goats survive where few others can, 168 00:14:05,533 --> 00:14:07,566 {\an1}even in the depths of winter. 169 00:14:12,366 --> 00:14:15,566 {\an1}Nannies and their week-old kids pick their way carefully 170 00:14:15,600 --> 00:14:19,166 {\an1}through the ever-softening snow. 171 00:14:19,200 --> 00:14:24,133 {\an1}Mom has memorized every nook and crag of this mountainside. 172 00:14:25,533 --> 00:14:28,866 {\an1}And she knows an avalanche risk when she sees one. 173 00:14:32,066 --> 00:14:35,433 Her kid was born into a vertical world, 174 00:14:35,466 --> 00:14:37,666 with all the tools he needs to become 175 00:14:37,700 --> 00:14:39,933 {\an1}an accomplished mountaineer. 176 00:14:41,400 --> 00:14:45,800 Now all he needs is experience, 177 00:14:45,833 --> 00:14:49,200 and he's enrolled in the ultimate master class. 178 00:14:59,466 --> 00:15:03,266 Their destination is a high alpine meadow 179 00:15:03,300 --> 00:15:06,133 they hope will have verdant new shoots. 180 00:15:06,166 --> 00:15:09,766 [ Thunder rumbling ] 181 00:15:09,800 --> 00:15:13,166 At 10,000 feet, weather can turn quickly. 182 00:15:19,300 --> 00:15:23,100 But mom is patient and reassuring. 183 00:15:23,133 --> 00:15:26,233 {\an1}And no one is better equipped to weather the storm. 184 00:15:44,466 --> 00:15:52,466 {\an8}♪♪♪ 185 00:15:54,466 --> 00:15:59,766 {\an8}♪♪♪ 186 00:15:59,800 --> 00:16:05,133 {\an8}♪♪♪ 187 00:16:05,166 --> 00:16:07,600 {\an1}As the days grow longer, 188 00:16:07,633 --> 00:16:12,333 {\an1}spring unfolds in a spectacular display of wildflowers. 189 00:16:13,866 --> 00:16:16,300 Bear grass covers the alpine meadows 190 00:16:16,333 --> 00:16:19,200 {\an1}of Glacier National Park. 191 00:16:19,233 --> 00:16:22,366 {\an1}And balsamroot blankets the low, rolling hills 192 00:16:22,400 --> 00:16:24,433 of Western Montana. 193 00:16:24,466 --> 00:16:32,466 {\an8}♪♪♪ 194 00:16:32,933 --> 00:16:36,566 {\an1}Rocky Mountain bighorn sheep and mountain goats 195 00:16:36,600 --> 00:16:38,833 eagerly gobble up the new blossoms. 196 00:16:38,866 --> 00:16:43,933 {\an8}♪♪♪ 197 00:16:43,966 --> 00:16:49,000 {\an8}♪♪♪ 198 00:16:49,033 --> 00:16:53,200 {\an1}Bighorn births are perfectly timed for this bounty of spring. 199 00:16:53,233 --> 00:16:55,366 [ Birds chirping ] 200 00:17:05,566 --> 00:17:08,600 And in secluded spots all along the mountainside, 201 00:17:08,633 --> 00:17:11,666 mothers are tending to their newborn lambs. 202 00:17:13,633 --> 00:17:18,200 {\an1}This imprinting isolation can last for several days. 203 00:17:18,233 --> 00:17:22,966 {\an1}It's a chance for mothers and young to bond with each other, 204 00:17:23,000 --> 00:17:25,966 {\an1}learning their individual scents and sounds 205 00:17:26,000 --> 00:17:28,566 before rejoining the rest of the herd. 206 00:17:32,500 --> 00:17:36,966 For one new family, that task is doubly hard. 207 00:17:39,700 --> 00:17:41,833 {\an1}She has birthed twins, 208 00:17:41,866 --> 00:17:45,466 an exceptionally rare occurrence for Bighorn sheep... 209 00:17:47,233 --> 00:17:50,133 {\an1}...and one that obviously makes the task of mothering 210 00:17:50,166 --> 00:17:52,033 twice as demanding. 211 00:18:02,133 --> 00:18:05,900 {\an1}With each passing hour, the twins grow stronger. 212 00:18:08,233 --> 00:18:10,700 [ Lamb bleats ] 213 00:18:10,733 --> 00:18:13,033 They are playful and energetic... 214 00:18:16,900 --> 00:18:19,166 but still wobbly on their feet. 215 00:18:21,766 --> 00:18:25,033 {\an1}Predation from mountain lions, coyotes, and golden eagles 216 00:18:25,066 --> 00:18:28,233 {\an1}are an ever-present threat, 217 00:18:28,266 --> 00:18:31,700 {\an1}and the sooner mom and the twins can rejoin the herd, 218 00:18:31,733 --> 00:18:33,433 {\an1}the safer they will be. 219 00:18:33,466 --> 00:18:39,600 {\an8}♪♪♪ 220 00:18:39,633 --> 00:18:43,666 {\an1}To survive in the Rockies, young must grow up fast... 221 00:18:46,333 --> 00:18:49,066 {\an1}...many within the span of a single season. 222 00:18:53,933 --> 00:18:56,400 {\an1}But in these early stages of life, 223 00:18:56,433 --> 00:18:59,600 {\an1}offspring are wholly dependent on their mother's care. 224 00:19:06,133 --> 00:19:10,566 {\an1}For some, the job is more demanding than others. 225 00:19:10,600 --> 00:19:16,166 {\an1}With 11 hungry pups to feed, this fox mom has her hands full. 226 00:19:19,566 --> 00:19:23,666 {\an1}Raising this many pups is not only a physically demanding job, 227 00:19:23,700 --> 00:19:26,233 but one that requires an extraordinary amount 228 00:19:26,266 --> 00:19:29,266 of patience... 229 00:19:29,300 --> 00:19:32,466 {\an1}which this mom seems to have in abundance. 230 00:19:38,000 --> 00:19:41,400 It's a good lesson for our mother of twins, 231 00:19:41,433 --> 00:19:44,000 and one she'll need to take to heart, 232 00:19:44,033 --> 00:19:47,066 as her lambs grow more adventurous. 233 00:19:48,200 --> 00:19:51,133 {\an1}[ Birds chirping, calling ] 234 00:19:58,800 --> 00:20:00,666 For one crane family, 235 00:20:00,700 --> 00:20:03,733 {\an1}the raising of their young has only just begun. 236 00:20:08,800 --> 00:20:13,266 {\an1}After a month of waiting, the eggs are beginning to hatch. 237 00:20:18,966 --> 00:20:21,433 One of the colts has already emerged, 238 00:20:21,466 --> 00:20:24,000 but his sibling is not quite ready. 239 00:20:25,933 --> 00:20:28,933 {\an1}The thick crane egg has been slowly weakening, 240 00:20:28,966 --> 00:20:31,133 {\an1}as the tiny colt inside absorbs 241 00:20:31,166 --> 00:20:34,233 the shells' calcium into her young bones. 242 00:20:34,266 --> 00:20:38,800 {\an8}♪♪♪ 243 00:20:38,833 --> 00:20:42,100 {\an1}This process can take hours. 244 00:20:42,133 --> 00:20:45,266 {\an1}And now that her first colt is out and ready to feed, 245 00:20:45,300 --> 00:20:48,300 mom is anxious for colt number two. 246 00:20:50,266 --> 00:20:53,133 {\an1}She nudges the egg to break the rest of the shell. 247 00:20:53,166 --> 00:21:01,166 {\an8}♪♪♪ 248 00:21:03,000 --> 00:21:11,000 {\an8}♪♪♪ 249 00:21:12,766 --> 00:21:14,600 {\an1}And with a gentle assist, 250 00:21:14,633 --> 00:21:18,133 {\an1}her second colt, still weak from its cramped quarters, 251 00:21:18,166 --> 00:21:20,600 is finally free. 252 00:21:20,633 --> 00:21:24,566 {\an8}♪♪♪ 253 00:21:24,600 --> 00:21:28,533 {\an8}♪♪♪ 254 00:21:28,566 --> 00:21:31,033 [ Duck quacking ] 255 00:21:35,366 --> 00:21:39,233 {\an1}Dad won't take any chances with visitors close by. 256 00:21:39,266 --> 00:21:46,466 {\an8}♪♪♪ 257 00:21:46,500 --> 00:21:48,000 {\an1}But within a few hours, 258 00:21:48,033 --> 00:21:50,900 both colts are shakily on their feet. 259 00:21:50,933 --> 00:21:58,933 {\an8}♪♪♪ 260 00:22:00,966 --> 00:22:02,200 Their first meal 261 00:22:02,233 --> 00:22:06,700 {\an1}will be the pulverized eggs they lived in. 262 00:22:06,733 --> 00:22:14,733 {\an8}♪♪♪ 263 00:22:16,266 --> 00:22:19,000 {\an1}This will help them grow strong from the start. 264 00:22:19,033 --> 00:22:25,066 {\an8}♪♪♪ 265 00:22:25,100 --> 00:22:31,100 {\an8}♪♪♪ 266 00:22:31,133 --> 00:22:35,966 {\an1}The first hatched is quick to challenge his sibling. 267 00:22:36,000 --> 00:22:41,000 {\an1}Like many first-time parents, they learn through experience. 268 00:22:41,033 --> 00:22:44,200 {\an1}By feeding the colts separately, they avoid in-fighting 269 00:22:44,233 --> 00:22:47,600 and ensure they both get equal portions of food. 270 00:22:50,866 --> 00:22:54,700 {\an1}Foraging through the muddy mess for small worms and insects 271 00:22:54,733 --> 00:22:58,866 {\an1}is a routine that comes more easily to some... 272 00:22:58,900 --> 00:23:00,566 than others. 273 00:23:07,333 --> 00:23:08,666 By the end of summer, 274 00:23:08,700 --> 00:23:12,300 {\an1}these tiny colts will be as tall as their parents. 275 00:23:16,766 --> 00:23:20,866 {\an1}The very act of having young heightens a mother's senses. 276 00:23:23,100 --> 00:23:24,566 And it is, by far, 277 00:23:24,600 --> 00:23:27,933 {\an1}the most consuming relationship in an animal's life. 278 00:23:31,433 --> 00:23:34,166 {\an1}A mother grizzly emerges from the dense forest 279 00:23:34,200 --> 00:23:37,766 {\an1}with three tiny cubs in tow. 280 00:23:37,800 --> 00:23:40,633 Named after the black volcanic glass 281 00:23:40,666 --> 00:23:45,466 {\an1}that forms Yellowstone's Obsidian Cliff, 282 00:23:45,500 --> 00:23:48,833 she leads her cubs on their first big outing. 283 00:23:48,866 --> 00:23:55,433 {\an8}♪♪♪ 284 00:23:55,466 --> 00:23:59,700 {\an1}Obsidian's cubs were born in the depths of winter. 285 00:23:59,733 --> 00:24:03,766 {\an1}And for months, their mother fed them, without eating. 286 00:24:06,166 --> 00:24:11,133 {\an1}These cubs are her entire world, and she is theirs. 287 00:24:11,166 --> 00:24:16,466 {\an8}♪♪♪ 288 00:24:16,500 --> 00:24:21,766 {\an8}♪♪♪ 289 00:24:21,800 --> 00:24:24,300 {\an1}Despite their fiercely protective mother, 290 00:24:24,333 --> 00:24:26,033 {\an1}these cubs are vulnerable 291 00:24:26,066 --> 00:24:29,533 {\an1}and sticking as close to mom as possible, 292 00:24:29,566 --> 00:24:31,833 trying hard to get her attention. 293 00:24:31,866 --> 00:24:37,900 {\an8}♪♪♪ 294 00:24:37,933 --> 00:24:41,300 {\an1}But Obsidian will need more than grasses to sustain them. 295 00:24:45,033 --> 00:24:48,600 {\an1}It's time to introduce her cubs to their new home... 296 00:24:50,900 --> 00:24:52,533 {\an1}...a fantastical world 297 00:24:52,566 --> 00:24:55,666 of bubbling pools and steaming mountains. 298 00:24:58,066 --> 00:25:01,533 {\an1}They live atop one of the largest active volcanic systems 299 00:25:01,566 --> 00:25:03,133 on Earth. 300 00:25:03,166 --> 00:25:08,833 {\an8}♪♪♪ 301 00:25:08,866 --> 00:25:13,133 {\an1}Beneath the Yellowstone Caldera is a reservoir of hot magma, 302 00:25:13,166 --> 00:25:14,966 30 miles deep. 303 00:25:17,566 --> 00:25:20,166 {\an1}And it lies just under their feet. 304 00:25:20,200 --> 00:25:25,233 {\an8}♪♪♪ 305 00:25:25,266 --> 00:25:27,033 {\an1}With each passing day, 306 00:25:27,066 --> 00:25:32,033 {\an1}Obsidian takes her cubs farther and farther into her territory. 307 00:25:32,066 --> 00:25:35,166 {\an1}But these journeys are not without their risks. 308 00:25:37,466 --> 00:25:39,566 A single encounter with a male grizzly 309 00:25:39,600 --> 00:25:41,900 {\an1}could prove fatal for the cubs. 310 00:25:41,933 --> 00:25:48,233 {\an8}♪♪♪ 311 00:25:48,266 --> 00:25:50,300 Obsidian will need to remain vigilant 312 00:25:50,333 --> 00:25:52,700 if she hopes to keep her family safe. 313 00:25:52,733 --> 00:25:59,133 {\an8}♪♪♪ 314 00:25:59,166 --> 00:26:05,666 {\an8}♪♪♪ 315 00:26:05,700 --> 00:26:12,100 {\an8}♪♪♪ 316 00:26:12,133 --> 00:26:18,533 {\an8}♪♪♪ 317 00:26:18,566 --> 00:26:19,966 {\an1}Up in the high elevation, 318 00:26:20,000 --> 00:26:23,566 these snow-free days won't last long. 319 00:26:23,600 --> 00:26:26,733 So, while mothers are busy feeding, 320 00:26:26,766 --> 00:26:31,433 {\an1}kids are getting to know their extended family 321 00:26:31,466 --> 00:26:34,700 {\an1}while playing an endless game of King of the Hill... 322 00:26:37,166 --> 00:26:39,633 learning skills that will prepare them 323 00:26:39,666 --> 00:26:42,166 {\an1}for life in a vertical world. 324 00:26:46,200 --> 00:26:51,033 Soon, mothers hurry to collect their kids 325 00:26:51,066 --> 00:26:53,200 {\an1}as the herd continues to move. 326 00:26:54,666 --> 00:26:58,033 [ Kid bleats ] 327 00:26:58,066 --> 00:26:59,800 {\an1}But amidst the excitement, 328 00:26:59,833 --> 00:27:02,533 {\an1}one kid has lost track of his mom. 329 00:27:05,833 --> 00:27:07,366 [ Bleats ] 330 00:27:07,400 --> 00:27:10,100 {\an1}He calls to her, but no reply. 331 00:27:12,966 --> 00:27:17,066 And he can't see or smell her anywhere. 332 00:27:17,100 --> 00:27:20,166 {\an1}All the goats are rapidly shedding their winter coats, 333 00:27:20,200 --> 00:27:23,000 {\an1}so mom looks different from day to day. 334 00:27:23,033 --> 00:27:28,300 {\an8}♪♪♪ 335 00:27:28,333 --> 00:27:31,566 {\an1}The only way to find out is to get close enough to smell. 336 00:27:31,600 --> 00:27:39,600 {\an8}♪♪♪ 337 00:27:40,833 --> 00:27:43,666 {\an1}One by one, he's rejected. 338 00:27:46,400 --> 00:27:48,466 Nobody seems to want him around. 339 00:27:51,533 --> 00:27:53,900 {\an1}The sun is beginning to set, 340 00:27:53,933 --> 00:27:56,900 {\an1}and the kid is growing increasingly anxious. 341 00:27:56,933 --> 00:28:02,500 {\an8}♪♪♪ 342 00:28:02,533 --> 00:28:08,033 {\an8}♪♪♪ 343 00:28:08,066 --> 00:28:09,633 {\an1}In a last-ditch effort, 344 00:28:09,666 --> 00:28:12,733 {\an1}he chases after a lone nanny walking away. 345 00:28:14,666 --> 00:28:17,233 When he reaches her, he sniffs cautiously, 346 00:28:17,266 --> 00:28:20,100 having made so many wrong guesses already. 347 00:28:21,966 --> 00:28:23,866 This time... 348 00:28:23,900 --> 00:28:25,466 he guessed right. 349 00:28:25,500 --> 00:28:31,500 {\an8}♪♪♪ 350 00:28:31,533 --> 00:28:33,933 As twilight descends over the mountain, 351 00:28:33,966 --> 00:28:36,866 {\an1}the two bed down together on a nearby cliff. 352 00:28:40,500 --> 00:28:43,300 The kid is overjoyed to have his mother back. 353 00:28:43,333 --> 00:28:45,133 [ Kid squeals ] 354 00:28:45,166 --> 00:28:48,966 On this mountain, their bond is everything. 355 00:28:49,000 --> 00:28:57,000 {\an8}♪♪♪ 356 00:28:59,966 --> 00:29:04,466 {\an1}A fog has enveloped the craggy peaks of western Montana. 357 00:29:09,133 --> 00:29:12,000 {\an1}Bighorn sheep are just beginning their day. 358 00:29:12,033 --> 00:29:18,833 {\an8}♪♪♪ 359 00:29:18,866 --> 00:29:23,566 {\an1}And for these young lambs, the fun is about to begin. 360 00:29:25,033 --> 00:29:26,533 {\an1}Playgroups have formed. 361 00:29:26,566 --> 00:29:34,566 {\an8}♪♪♪ 362 00:29:36,566 --> 00:29:44,566 {\an8}♪♪♪ 363 00:29:46,566 --> 00:29:53,066 {\an8}♪♪♪ 364 00:29:53,100 --> 00:29:56,400 {\an1}Many lambs are still timid, uneasy with their footing 365 00:29:56,433 --> 00:29:58,633 {\an1}on the steep testing ground 366 00:29:58,666 --> 00:30:02,666 packed so tightly with the rest of the young. 367 00:30:02,700 --> 00:30:06,100 {\an1}Mothers, too, are rightfully concerned with their world 368 00:30:06,133 --> 00:30:08,266 so suddenly expanded, 369 00:30:08,300 --> 00:30:11,400 they must try to keep their young ones safe. 370 00:30:11,433 --> 00:30:19,433 {\an8}♪♪♪ 371 00:30:20,100 --> 00:30:28,100 {\an8}♪♪♪ 372 00:30:28,766 --> 00:30:31,733 These young rams have no such concerns. 373 00:30:31,766 --> 00:30:39,766 {\an8}♪♪♪ 374 00:30:41,766 --> 00:30:45,266 {\an1}And they seem intent on provoking this year's new lambs 375 00:30:45,300 --> 00:30:46,866 into action. 376 00:30:46,900 --> 00:30:51,733 {\an8}♪♪♪ 377 00:30:51,766 --> 00:30:53,666 {\an1}If they can brave these games, 378 00:30:53,700 --> 00:30:56,600 {\an1}it will serve them well in the years ahead. 379 00:31:02,066 --> 00:31:06,866 {\an1}Bighorn sheep form alliances that last lifetimes. 380 00:31:06,900 --> 00:31:09,866 {\an1}The twins have settled into this new friend group, 381 00:31:09,900 --> 00:31:12,633 almost as important as their mother's care. 382 00:31:25,033 --> 00:31:28,166 {\an1}Mom is quick to comfort her small lamb 383 00:31:28,200 --> 00:31:31,133 but equally quick to nudge him back into play. 384 00:31:33,200 --> 00:31:36,400 {\an1}Building confidence is crucial to their survival. 385 00:31:36,433 --> 00:31:44,433 {\an8}♪♪♪ 386 00:31:46,033 --> 00:31:50,500 {\an1}For parents, growing up seems to happen in the blink of an eye. 387 00:31:53,566 --> 00:31:58,066 For young, every day brings a new adventure. 388 00:31:58,100 --> 00:32:06,100 {\an8}♪♪♪ 389 00:32:06,900 --> 00:32:09,700 It's all about building relationships... 390 00:32:09,733 --> 00:32:15,100 {\an8}♪♪♪ 391 00:32:15,133 --> 00:32:17,433 {\an1}...testing your boundaries... 392 00:32:20,700 --> 00:32:23,566 and finding out... 393 00:32:23,600 --> 00:32:26,266 {\an1}exactly what you're capable of. 394 00:32:26,300 --> 00:32:34,166 {\an8}♪♪♪ 395 00:32:34,200 --> 00:32:42,066 {\an8}♪♪♪ 396 00:32:42,100 --> 00:32:49,933 {\an8}♪♪♪ 397 00:32:49,966 --> 00:32:57,833 {\an8}♪♪♪ 398 00:32:57,866 --> 00:33:05,800 {\an8}♪♪♪ 399 00:33:05,833 --> 00:33:08,866 [ Birds chirping ] 400 00:33:08,900 --> 00:33:13,166 {\an1}Raising these young colts is keeping Mom and Dad busy. 401 00:33:14,266 --> 00:33:16,933 {\an1}Colts have the appetite of a teenager 402 00:33:16,966 --> 00:33:20,400 {\an1}and can grow an inch a day. 403 00:33:20,433 --> 00:33:22,400 {\an1}They will need every morsel 404 00:33:22,433 --> 00:33:25,433 {\an1}if they are going to migrate south this autumn. 405 00:33:28,233 --> 00:33:32,100 {\an1}But this family has a bigger problem on their hands. 406 00:33:32,133 --> 00:33:34,300 [ Bell ringing, lawnmower running ] 407 00:33:37,733 --> 00:33:39,200 Their little wetland 408 00:33:39,233 --> 00:33:42,633 {\an1}is wedged in the middle of a sea of townhouses. 409 00:33:45,000 --> 00:33:49,100 {\an1}Long before this suburb of Bozeman, Montana, was here, 410 00:33:49,133 --> 00:33:52,400 {\an1}this area was part of a vast network of wetlands 411 00:33:52,433 --> 00:33:56,833 {\an1}that may have been home to generations of cranes. 412 00:33:56,866 --> 00:33:59,100 {\an1}[ Train whistle blowing in distance ] 413 00:34:02,266 --> 00:34:06,066 {\an1}This couple has stubbornly clung to this tiny patch of wetland, 414 00:34:06,100 --> 00:34:10,066 but that's become a dangerous choice. 415 00:34:10,100 --> 00:34:14,200 {\an1}Only about 1 in 10 colts survive to adulthood, 416 00:34:14,233 --> 00:34:18,100 {\an1}and those odds are considerably worse in urban settings. 417 00:34:21,766 --> 00:34:24,600 Even as protective as these parents are, 418 00:34:24,633 --> 00:34:26,300 in this urban maze, 419 00:34:26,333 --> 00:34:29,733 {\an1}they will need a new set of skills to survive. 420 00:34:29,766 --> 00:34:32,966 [ Dog barking ] 421 00:34:33,000 --> 00:34:35,400 [ Panting ] 422 00:34:37,266 --> 00:34:40,000 {\an1}Dad paces rapidly back and forth, 423 00:34:40,033 --> 00:34:42,666 {\an1}tossing grass and sticks into the air. 424 00:34:42,700 --> 00:34:45,000 [ Crane squawks ] 425 00:34:45,033 --> 00:34:48,466 {\an1}He's sending a message... "Stay back!" 426 00:34:53,600 --> 00:34:55,633 [ Children playing ] 427 00:34:58,233 --> 00:35:03,533 {\an1}Safety and security are choices typically made with their wings. 428 00:35:03,566 --> 00:35:07,100 But until these colts are old enough to fly, 429 00:35:07,133 --> 00:35:09,266 {\an1}this family is grounded. 430 00:35:16,000 --> 00:35:20,600 {\an1}But the colts are growing fast. 431 00:35:20,633 --> 00:35:22,233 {\an1}And their parents must decide 432 00:35:22,266 --> 00:35:25,200 {\an1}just how much of the suburbs they can take. 433 00:35:28,600 --> 00:35:32,833 {\an1}Once the family leaves their home, there's no looking back. 434 00:35:34,866 --> 00:35:36,666 {\an1}If they are to find safety, 435 00:35:36,700 --> 00:35:40,200 {\an1}they will need to make the journey on foot. 436 00:35:40,233 --> 00:35:43,433 {\an1}[ Motorcycle engine revs in distance ] 437 00:35:48,600 --> 00:35:51,100 [ Truck horn honks, vehicles passing ] 438 00:36:12,766 --> 00:36:20,366 {\an8}♪♪♪ 439 00:36:20,400 --> 00:36:28,033 {\an8}♪♪♪ 440 00:36:28,066 --> 00:36:31,733 {\an1}The parents take their first cautious steps into the road. 441 00:36:31,766 --> 00:36:36,733 {\an8}♪♪♪ 442 00:36:36,766 --> 00:36:38,333 And the tiny colts 443 00:36:38,366 --> 00:36:41,600 {\an1}slide down the hot asphalt to follow behind. 444 00:36:41,633 --> 00:36:47,833 {\an8}♪♪♪ 445 00:36:47,866 --> 00:36:51,733 {\an1}This 4-lane road is the most exposed these colts have been 446 00:36:51,766 --> 00:36:53,233 in their young lives. 447 00:36:53,266 --> 00:36:58,700 {\an8}♪♪♪ 448 00:36:58,733 --> 00:37:04,200 {\an8}♪♪♪ 449 00:37:04,233 --> 00:37:06,900 {\an1}Much like walking a tight rope, 450 00:37:06,933 --> 00:37:10,366 {\an1}you have to keep looking straight ahead. 451 00:37:10,400 --> 00:37:13,500 Whatever you do, don't look down... 452 00:37:13,533 --> 00:37:14,533 on the road. 453 00:37:14,566 --> 00:37:17,066 [ Horn blaring ] 454 00:37:17,100 --> 00:37:21,300 {\an8}♪♪♪ 455 00:37:21,333 --> 00:37:25,100 [ Horns blaring ] 456 00:37:25,133 --> 00:37:31,033 {\an8}♪♪♪ 457 00:37:31,066 --> 00:37:36,966 {\an8}♪♪♪ 458 00:37:37,000 --> 00:37:38,333 [ Horn blares ] 459 00:37:38,366 --> 00:37:46,366 {\an8}♪♪♪ 460 00:37:46,766 --> 00:37:49,800 They have survived their first big step. 461 00:38:01,100 --> 00:38:04,600 {\an1}Growing up and raising a family is tough enough, 462 00:38:04,633 --> 00:38:08,666 but we've made that task doubly hard. 463 00:38:08,700 --> 00:38:11,800 Expanding suburbs and industrial development 464 00:38:11,833 --> 00:38:15,333 {\an1}continue to fragment habitat across the Rockies. 465 00:38:18,500 --> 00:38:22,833 {\an1}For some, roads and fences become barriers to migration... 466 00:38:25,733 --> 00:38:27,600 {\an1}...often splitting apart families 467 00:38:27,633 --> 00:38:30,466 and making animals vulnerable to predators. 468 00:38:30,500 --> 00:38:36,366 {\an8}♪♪♪ 469 00:38:36,400 --> 00:38:42,300 {\an1}And each year, the wild becomes just a little less so. 470 00:38:45,933 --> 00:38:49,933 {\an1}Yet the Rockies still remain our last best chance 471 00:38:49,966 --> 00:38:54,500 {\an1}for preserving many of North America's most iconic species. 472 00:38:54,533 --> 00:38:59,766 {\an8}♪♪♪ 473 00:38:59,800 --> 00:39:05,133 {\an8}♪♪♪ 474 00:39:05,166 --> 00:39:08,433 {\an1}By early summer, snow that has been locked away 475 00:39:08,466 --> 00:39:12,233 {\an1}in these high mountain peaks begins to melt away. 476 00:39:15,033 --> 00:39:18,766 {\an1}Rivers swell as spring run-off reaches its peak. 477 00:39:21,233 --> 00:39:23,433 {\an1}It's a powerful force. 478 00:39:23,466 --> 00:39:27,033 {\an1}The Lamar River is raging. 479 00:39:27,066 --> 00:39:31,200 {\an1}And this presents a new set of challenges for our bison herd. 480 00:39:35,600 --> 00:39:38,433 {\an1}The cold, quick-moving water bottles up the herd 481 00:39:38,466 --> 00:39:40,100 at the shoreline. 482 00:39:40,133 --> 00:39:44,033 {\an1}As the leaders wade out, testing the current strength... 483 00:39:45,600 --> 00:39:50,266 {\an1}...calves must stay close, trust in the herd, 484 00:39:50,300 --> 00:39:51,866 and remain calm. 485 00:39:51,900 --> 00:39:59,466 {\an8}♪♪♪ 486 00:39:59,500 --> 00:40:07,033 {\an8}♪♪♪ 487 00:40:07,066 --> 00:40:09,166 {\an1}The current is beginning to pick up 488 00:40:09,200 --> 00:40:12,300 {\an1}and causing many newcomers second thoughts. 489 00:40:12,333 --> 00:40:20,333 {\an8}♪♪♪ 490 00:40:20,900 --> 00:40:26,033 {\an1}Midway, in the deepest section, panic sets in. 491 00:40:26,066 --> 00:40:28,233 {\an1}The calf tries to turn back. 492 00:40:31,866 --> 00:40:35,833 {\an1}Quickly, he's swept downriver, 493 00:40:35,866 --> 00:40:38,266 farther and farther from his mother. 494 00:40:38,300 --> 00:40:45,433 {\an8}♪♪♪ 495 00:40:45,466 --> 00:40:47,700 {\an1}He struggles to swim upstream... 496 00:40:50,800 --> 00:40:54,200 {\an1}...as his mom can only watch from the shoreline. 497 00:40:54,233 --> 00:40:59,333 {\an8}♪♪♪ 498 00:40:59,366 --> 00:41:02,733 His legs slow from icy-cold exhaustion... 499 00:41:02,766 --> 00:41:10,766 {\an8}♪♪♪ 500 00:41:12,766 --> 00:41:20,766 {\an8}♪♪♪ 501 00:41:22,766 --> 00:41:28,000 {\an8}♪♪♪ 502 00:41:28,033 --> 00:41:33,233 {\an8}♪♪♪ 503 00:41:33,266 --> 00:41:36,366 {\an1}...the lucky calf is reunited with Mom. 504 00:41:40,933 --> 00:41:42,266 Maybe a little wiser 505 00:41:42,300 --> 00:41:46,000 about the power of the wild world around him. 506 00:41:46,033 --> 00:41:51,100 {\an8}♪♪♪ 507 00:41:51,133 --> 00:41:56,200 {\an8}♪♪♪ 508 00:41:56,233 --> 00:42:00,500 Not all youngsters in Yellowstone Valley are so lucky. 509 00:42:00,533 --> 00:42:02,633 [ Thunder rumbling ] 510 00:42:13,266 --> 00:42:18,133 {\an1}Sometime in the twilight hours, tragedy struck. 511 00:42:18,166 --> 00:42:20,600 [ Bats screeching ] 512 00:42:20,633 --> 00:42:27,500 {\an8}♪♪♪ 513 00:42:27,533 --> 00:42:34,433 {\an8}♪♪♪ 514 00:42:34,466 --> 00:42:36,800 [ Birds chirping ] 515 00:42:36,833 --> 00:42:38,566 {\an1}Now, in the light of day, 516 00:42:38,600 --> 00:42:42,733 {\an1}Obsidian seems restless, nervous. 517 00:42:42,766 --> 00:42:47,566 {\an8}♪♪♪ 518 00:42:47,600 --> 00:42:49,833 {\an1}She huffs to call her cubs. 519 00:42:49,866 --> 00:42:53,900 {\an8}♪♪♪ 520 00:42:53,933 --> 00:42:57,100 {\an1}But now her family of three... 521 00:42:57,133 --> 00:42:58,700 is down to two. 522 00:42:58,733 --> 00:43:03,666 {\an8}♪♪♪ 523 00:43:03,700 --> 00:43:05,800 {\an1}One of her cubs is missing. 524 00:43:09,533 --> 00:43:11,633 We may never know just what happened 525 00:43:11,666 --> 00:43:15,866 {\an1}in those twilight hours, but the cubs certainly do. 526 00:43:15,900 --> 00:43:20,333 {\an8}♪♪♪ 527 00:43:22,133 --> 00:43:26,533 {\an1}Losing a youngster has made Obsidian even more vigilant. 528 00:43:43,633 --> 00:43:48,033 {\an1}She retreats into the forest to nurse her two remaining cubs. 529 00:43:53,533 --> 00:43:56,800 No family is immune to the harsh reality 530 00:43:56,833 --> 00:44:00,233 {\an1}of growing up in the Rockies. 531 00:44:00,266 --> 00:44:02,800 Life here is tenuous. 532 00:44:05,233 --> 00:44:10,100 {\an1}And while the loss of life for one means survival for another, 533 00:44:10,133 --> 00:44:12,333 {\an1}nothing is ever so simple. 534 00:44:13,900 --> 00:44:16,033 Our bison herd rushes to the place 535 00:44:16,066 --> 00:44:19,700 {\an1}where one of their own has fallen... 536 00:44:19,733 --> 00:44:22,166 {\an1}a female that died during labor. 537 00:44:25,500 --> 00:44:30,600 {\an1}We gather together to mourn the loss of our loved ones. 538 00:44:30,633 --> 00:44:34,733 {\an1}Is it so difficult to imagine that bison may do the same? 539 00:44:34,766 --> 00:44:38,833 {\an8}♪♪♪ 540 00:44:38,866 --> 00:44:42,966 {\an1}Tails are raised in distress by the sight of a wolf 541 00:44:43,000 --> 00:44:44,766 waiting in the wings. 542 00:44:47,166 --> 00:44:50,366 Eventually, the herd begins to disperse... 543 00:44:53,366 --> 00:44:56,800 {\an1}...leaving one lone 3-year-old. 544 00:44:56,833 --> 00:45:00,266 {\an1}Perhaps a son, still grieving. 545 00:45:00,300 --> 00:45:04,933 {\an8}♪♪♪ 546 00:45:04,966 --> 00:45:09,433 {\an1}While his sense of smell clearly tells him she's gone, 547 00:45:09,466 --> 00:45:12,633 {\an1}he's determined to defend her a while longer. 548 00:45:12,666 --> 00:45:17,933 {\an8}♪♪♪ 549 00:45:17,966 --> 00:45:22,200 {\an1}There is far more that connects us than separates us, 550 00:45:22,233 --> 00:45:25,700 especially in matters of love and loss. 551 00:45:25,733 --> 00:45:31,100 {\an8}♪♪♪ 552 00:45:31,133 --> 00:45:36,533 {\an8}♪♪♪ 553 00:45:36,566 --> 00:45:41,033 {\an1}In the small clearing, Obsidian is still nursing her cubs. 554 00:45:41,066 --> 00:45:45,600 {\an8}♪♪♪ 555 00:45:45,633 --> 00:45:49,533 {\an1}A shadow on the hillside above her draws her to her feet, 556 00:45:49,566 --> 00:45:52,033 {\an1}perhaps a passing bison. 557 00:45:52,066 --> 00:45:55,433 But Mom is not taking any chances now. 558 00:46:06,300 --> 00:46:10,033 {\an1}She keeps a watchful eye while her cubs play. 559 00:46:11,800 --> 00:46:15,666 {\an1}Obsidian faces the same struggle of every parent... 560 00:46:15,700 --> 00:46:18,466 {\an1}how much freedom is too much? 561 00:46:18,500 --> 00:46:26,500 {\an8}♪♪♪ 562 00:46:27,566 --> 00:46:35,566 {\an8}♪♪♪ 563 00:46:36,633 --> 00:46:41,133 {\an1}As the summer sun bakes the plains, tensions are building. 564 00:46:43,933 --> 00:46:47,266 It's mating season. 565 00:46:47,300 --> 00:46:51,366 {\an1}And for our young calf, everything has suddenly changed. 566 00:46:53,366 --> 00:46:57,033 {\an1}For months, he's been tied to his mother's side, 567 00:46:57,066 --> 00:46:59,866 but now her attention is focused elsewhere. 568 00:46:59,900 --> 00:47:05,566 {\an8}♪♪♪ 569 00:47:05,600 --> 00:47:08,200 {\an1}And the large bulls he's watched all summer 570 00:47:08,233 --> 00:47:12,833 {\an1}are suddenly too close for comfort. 571 00:47:12,866 --> 00:47:17,533 They're agitated and chasing his mother around. 572 00:47:17,566 --> 00:47:21,833 {\an1}He tries to keep up with her, but that's a dangerous choice. 573 00:47:21,866 --> 00:47:29,333 {\an8}♪♪♪ 574 00:47:29,366 --> 00:47:30,733 This time of year, 575 00:47:30,766 --> 00:47:33,500 bulls are competing for the right to breed. 576 00:47:33,533 --> 00:47:38,766 {\an8}♪♪♪ 577 00:47:38,800 --> 00:47:42,766 {\an1}And they display their fitness in the most dramatic fashion... 578 00:47:42,800 --> 00:47:47,233 {\an1}kicking clouds of dust into the air as they urinate 579 00:47:47,266 --> 00:47:49,866 and then roll their 2,000-pound bodies 580 00:47:49,900 --> 00:47:51,600 {\an1}against the bare earth. 581 00:47:53,800 --> 00:47:57,000 {\an1}This bull is sending a message. 582 00:47:57,033 --> 00:47:59,100 {\an1}It's a chemical billboard. 583 00:48:01,066 --> 00:48:05,233 {\an1}It tells the other bulls he is at the peak of his game. 584 00:48:05,266 --> 00:48:12,766 {\an8}♪♪♪ 585 00:48:12,800 --> 00:48:20,300 {\an8}♪♪♪ 586 00:48:20,333 --> 00:48:23,200 {\an1}One of the large bulls is sticking close 587 00:48:23,233 --> 00:48:25,733 to the calf's mother, tending her. 588 00:48:25,766 --> 00:48:33,766 {\an8}♪♪♪ 589 00:48:33,966 --> 00:48:36,266 But he's treading a difficult path. 590 00:48:39,733 --> 00:48:41,600 He's surrounded... 591 00:48:41,633 --> 00:48:44,100 {\an1}and the competition is stiff. 592 00:48:44,133 --> 00:48:50,633 {\an8}♪♪♪ 593 00:48:50,666 --> 00:48:53,366 {\an1}If he wants to keep her to himself, 594 00:48:53,400 --> 00:48:55,633 {\an1}he's going to have to prove that he can. 595 00:48:55,666 --> 00:49:02,833 {\an8}♪♪♪ 596 00:49:02,866 --> 00:49:09,933 {\an8}♪♪♪ 597 00:49:09,966 --> 00:49:12,766 {\an1}It's a deadly serious game. 598 00:49:12,800 --> 00:49:20,800 {\an8}♪♪♪ 599 00:49:21,733 --> 00:49:24,100 The success of future generations 600 00:49:24,133 --> 00:49:28,966 {\an1}depends upon the outcome of these gladiatorial battles. 601 00:49:29,000 --> 00:49:33,300 {\an8}♪♪♪ 602 00:49:33,333 --> 00:49:37,266 And as the two bulls exhaust themselves, 603 00:49:37,300 --> 00:49:39,533 {\an1}someone seizes an opening. 604 00:49:39,566 --> 00:49:47,566 {\an8}♪♪♪ 605 00:49:49,166 --> 00:49:57,166 {\an8}♪♪♪ 606 00:49:57,766 --> 00:50:05,766 {\an8}♪♪♪ 607 00:50:07,766 --> 00:50:12,233 {\an1}Amidst the chaos, the calves seek comfort in each other. 608 00:50:17,500 --> 00:50:21,400 {\an1}And as with every competition, there is a victor. 609 00:50:21,433 --> 00:50:27,733 {\an8}♪♪♪ 610 00:50:27,766 --> 00:50:31,300 These are the calves' last days of childhood. 611 00:50:31,333 --> 00:50:34,766 {\an1}And in just a few years, they'll compete for real. 612 00:50:34,800 --> 00:50:40,300 {\an8}♪♪♪ 613 00:50:40,333 --> 00:50:44,066 {\an1}If they hope to be so fortunate, they must endure 614 00:50:44,100 --> 00:50:46,933 all that the Rockies have in store for them 615 00:50:46,966 --> 00:50:48,533 in the months ahead. 616 00:50:48,566 --> 00:50:55,300 {\an8}♪♪♪ 617 00:50:55,333 --> 00:50:59,666 {\an1}As colors shift into autumn, 618 00:50:59,700 --> 00:51:02,333 {\an1}Obsidian's calm demeanor has returned. 619 00:51:02,366 --> 00:51:04,300 [ Birds chirping ] 620 00:51:06,800 --> 00:51:09,566 She calls for her two remaining cubs. 621 00:51:09,600 --> 00:51:11,633 [ Obsidian growls ] 622 00:51:11,666 --> 00:51:14,233 {\an1}Now, at the end of their season, 623 00:51:14,266 --> 00:51:16,800 her cubs are chubby and confident 624 00:51:16,833 --> 00:51:20,000 {\an1}as they follow after Mom. 625 00:51:20,033 --> 00:51:25,200 {\an1}Soon, Obsidian and her cubs will retreat to the warmth 626 00:51:25,233 --> 00:51:28,733 {\an1}and safety of their winter den. 627 00:51:28,766 --> 00:51:32,066 {\an1}While some take refuge underground, 628 00:51:32,100 --> 00:51:35,100 others must prepare to head south 629 00:51:35,133 --> 00:51:38,000 {\an1}to outrun winter's icy grip. 630 00:51:40,066 --> 00:51:41,766 But for many others, 631 00:51:41,800 --> 00:51:45,233 {\an1}they will have to endure winter's fury head on. 632 00:51:48,233 --> 00:51:50,266 There will be battles to fight... 633 00:51:52,600 --> 00:51:54,966 {\an1}...and alliances to forge. 634 00:51:56,400 --> 00:51:59,900 {\an1}Some must rely on the strength of their tribe. 635 00:52:02,866 --> 00:52:05,433 {\an1}While others must go it alone. 636 00:52:06,933 --> 00:52:09,666 {\an1}For all these brave souls, 637 00:52:09,700 --> 00:52:13,966 {\an1}the experience of growing up in the Rockies 638 00:52:14,000 --> 00:52:16,066 has only just begun. 639 00:52:16,100 --> 00:52:23,100 {\an8}♪♪♪ 640 00:52:25,233 --> 00:52:33,233 {\an8}♪♪♪ 641 00:52:33,333 --> 00:52:41,333 {\an8}♪♪♪ 642 00:52:41,433 --> 00:52:49,433 {\an8}♪♪♪ 643 00:52:49,533 --> 00:52:57,533 {\an8}♪♪♪ 644 00:52:57,633 --> 00:52:59,633 {\an8}To learn more about what you've seen 645 00:52:59,666 --> 00:53:01,266 {\an7}on this "Nature" program, 646 00:53:01,300 --> 00:53:03,466 {\an8}visit pbs.org. 647 00:53:03,500 --> 00:53:11,500 {\an8}♪♪♪