1  
00:00:09,400 --> 00:00:14,876  
北极始终是最严酷的试炼场，  
The Arctic has always been the toughest test,  

2  
00:00:14,900 --> 00:00:18,342  
尤其在阿拉斯加最偏远的角落——  
no more so than in the far corner of Alaska  

3  
00:00:18,366 --> 00:00:22,276  
北极国家野生动物保护区。  
called the Arctic National Wildlife Refuge.  

4  
00:00:22,300 --> 00:00:25,500  
成千上万的驯鹿直面严寒...  
Thousands of caribou face the cold...  

5  
00:00:27,266 --> 00:00:30,042  
险峻地形...  
the terrain...  

6  
00:00:30,066 --> 00:00:35,109  
与凶悍掠食者，只为抵达那片应许之地  
and formidable predators to reach one special place  

7  
00:00:35,133 --> 00:00:37,176  
在完美时机...  
at just the right time...  

8  
00:00:37,200 --> 00:00:41,533  
北冰洋边缘那片广袤而美丽的平原。  
a vast, beautiful plain on the edge of the Arctic Ocean.  

9  
00:00:43,966 --> 00:00:46,200  
它们在此诞育新生命。  
Here, they give birth.  

10  
00:00:49,166 --> 00:00:52,609  
这是北美大陆最后一场伟大迁徙的传奇，  
This is the story of the last great land migration  

11  
00:00:52,633 --> 00:00:54,266  
也是北极生灵们  
in North America.  

12  
00:00:56,466 --> 00:01:01,742  
从亘古往昔迈向截然不同未来的  
And of how every Arctic creature is now on a daunting journey  

13  
00:01:01,766 --> 00:01:05,909  
壮烈征程。  
from a timeless past into a vastly different future.  

14  
00:01:53,233 --> 00:01:55,209  
在世界之巅，  
On the top of the world,  

15  
00:01:55,233 --> 00:01:57,876  
冰河时代仍在延续。  
it is still the ice age.  

16  
00:02:10,166 --> 00:02:13,276  
这里是冬季的阿拉斯加北部。  
It's northern Alaska in winter.  

17  
00:02:13,300 --> 00:02:15,709  
气温骤降至零下50度。  
The temperature drops to 50 below.  

18  
00:02:27,200 --> 00:02:30,742  
冰冻的河流自布鲁克斯山脉向北蜿蜒，  
Frozen rivers curl north from the Brooks Range  

19  
00:02:30,766 --> 00:02:33,976  
延伸至毗邻波弗特海的广袤平原，  
and down to a plain stretching to the Beaufort Sea  

20  
00:02:34,000 --> 00:02:37,109  
此刻的北冰洋已被冰封。  
and the Arctic Ocean, now locked in ice.  

21  
00:02:40,733 --> 00:02:43,342  
这片绵延的白色山脉、  
This vast stretch of white mountains,  

22  
00:02:43,366 --> 00:02:45,476  
苔原与冰河，  
tundra, and icy rivers,  

23  
00:02:45,500 --> 00:02:48,942  
构成了地球上最重要的荒野之一——  
forms one of the world's most important wildernesses...  

24  
00:02:48,966 --> 00:02:52,609  
北极国家野生动物保护区。  
The Arctic National Wildlife Refuge.  

25  
00:02:52,633 --> 00:02:56,033  
这里是远古勇者们最后的家园。  
It's a home for courageous creatures from another time.  

26  
00:03:00,300 --> 00:03:03,209  
这片野生动物群落将面临  
This wildlife community will face a year  

27  
00:03:03,233 --> 00:03:04,966  
充满抉择的一年。  
of difficult decisions.  

28  
00:03:08,200 --> 00:03:12,742  
东南方数百英里外，最勇敢的或许当属  
Hundreds of miles southeast, bravest of all perhaps,  

29  
00:03:12,766 --> 00:03:16,242  
这头怀孕的驯鹿。  
is a pregnant caribou.  

30  
00:03:16,266 --> 00:03:19,209  
她属于豪猪驯鹿族群，  
She's part of the Porcupine caribou herd  

31  
00:03:19,233 --> 00:03:22,442  
即将踏上地球上最漫长的  
and will undertake the longest annual land migration  

32  
00:03:22,466 --> 00:03:24,509  
年度陆地迁徙。  
on the planet.  

33  
00:03:24,533 --> 00:03:28,176  
她一生行走的距离，  
In her lifetime, she's likely to walk the same distance  

34  
00:03:28,200 --> 00:03:32,276  
可绕行地球整整一圈。  
as a complete circuit of the globe.  

35  
00:03:32,300 --> 00:03:35,376  
时值十二月，驯鹿群正在等待，  
It's December, and the caribou are waiting,  

36  
00:03:35,400 --> 00:03:38,109  
在暮色中啃食地衣。  
eating lichen in the twilight.  

37  
00:03:38,133 --> 00:03:42,476  
接下来的旅程需要精准计时。  
The journey ahead needs precise timing.  

38  
00:03:42,500 --> 00:03:44,676  
她将穿越森林、  
She'll march through forests,  

39  
00:03:44,700 --> 00:03:46,942  
翻越高山、横渡冰河，  
over mountains, across rivers,  

40  
00:03:46,966 --> 00:03:48,609  
奔赴海岸平原。  
to the coastal plain.  

41  
00:03:48,633 --> 00:03:52,476  
往返旅程近千英里。  
It's a round trip of almost a thousand miles.  

42  
00:03:56,333 --> 00:03:58,942  
约十六万头驯鹿  
Some 160,000 caribou  

43  
00:03:58,966 --> 00:04:00,909  
将从育空地区  
will walk from their wintering grounds  

44  
00:04:00,933 --> 00:04:03,709  
与西北领地的越冬地出发，  
in the Yukon and Northwest Territories  

45  
00:04:03,733 --> 00:04:07,233  
前往野生动物保护区的产犊地。  
to their calving grounds in the Wildlife Refuge.  

46  
00:04:11,566 --> 00:04:14,109  
布鲁克斯山脉横亘在前，  
The Brooks Range stands in their way,  

47  
00:04:14,133 --> 00:04:17,742  
与海岸线平行延伸。  
running parallel to the coast.  

48  
00:04:17,766 --> 00:04:21,409  
太阳落下后，新年来临前将不再升起。  
The sun sets for the last time until the New Year.  

49  
00:04:32,400 --> 00:04:35,976  
唯一的光源是冬月反射的微光。  
The only sunlight is reflected by a wintry moon.  

50  
00:04:44,500 --> 00:04:46,409  
数百英里高空，  
Hundreds of miles above,  

51  
00:04:46,433 --> 00:04:50,076  
太阳辐射激发电离层，  
solar radiation fires up the ionosphere,  

52  
00:04:50,100 --> 00:04:51,709  
幻化出幽灵般的极光。  
and the ghostly aurora.  

53  
00:05:07,400 --> 00:05:09,676  
在这个世界里，  
This is a world of huge planetary  

54  
00:05:09,700 --> 00:05:13,142  
行星级伟力永恒涌动。  
forces in constant flux.  

55  
00:05:13,166 --> 00:05:17,742  
这是自然最壮丽与极致的呈现。  
This is nature at its most spectacular and extreme.  

56  
00:05:29,300 --> 00:05:33,476  
一月的黎明微光再度降临。  
A dawn twilight returns in January.  

57  
00:05:41,800 --> 00:05:44,642  
暴风雪席卷苔原。  
Blizzards blast the tundra.  

58  
00:05:44,666 --> 00:05:49,076  
多数动物早已离开或深藏雪下冬眠，  
Most animals have left or are hibernating under the deep snow,  

59  
00:05:49,100 --> 00:05:50,842  
但麝牛依然坚守。  
but musk ox remain.  

60  
00:05:56,766 --> 00:06:01,042  
它们忠于领地绝不离去。  
They are loyal to a home range and won't leave.  

61  
00:06:01,066 --> 00:06:03,276  
极少涉足山谷，  
They rarely visit the valley.  

62  
00:06:03,300 --> 00:06:04,909  
因积雪过深，  
The snow is too deep,  

63  
00:06:04,933 --> 00:06:08,176  
无法掘取冰冻的草料。  
and they can't dig out the frozen grass.  

64  
00:06:08,200 --> 00:06:11,033  
即便在高处觅食也非易事。  
Even up here, it's hard work.  

65  
00:06:16,566 --> 00:06:20,176  
近年冬季愈发变幻莫测，  
Winters seem to be more erratic recently,  

66  
00:06:20,200 --> 00:06:22,576  
平均气温比五十年前  
on average more than eight degrees warmer  

67  
00:06:22,600 --> 00:06:26,342  
升高逾八度，看似好转，  
than 50 years ago, which sounds better,  

68  
00:06:26,366 --> 00:06:30,266  
但如今暴雪之上又添冻雨。  
but now there's freezing rain on top of heavier snowfall.  

69  
00:06:33,433 --> 00:06:35,942  
驯鹿群开始躁动不安。  
The caribou are becoming restless.  

70  
00:06:41,466 --> 00:06:45,409  
她腹中的幼崽正日渐成长。  
Her belly is beginning to swell with her unborn calf.  

71  
00:06:50,866 --> 00:06:55,942  
她搜寻着驯鹿苔藓——冬季的食粮。  
She's searching for reindeer lichen, her winter food.  

72  
00:06:55,966 --> 00:06:59,142  
她既是驯鹿也是北美驯鹿，  
She's a reindeer as much as a caribou.  

73  
00:06:59,166 --> 00:07:01,276  
二者本属同种。  
They are the same species.  

74  
00:07:06,700 --> 00:07:10,876  
她和麝牛一样刨雪觅食。  
She digs through snow like the musk ox.  

75  
00:07:10,900 --> 00:07:12,542  
对这位准母亲而言，  
For a prospective mother,  

76  
00:07:12,566 --> 00:07:16,376  
获取充足食物是首要任务。  
finding enough food is her principal focus.  

77  
00:07:16,400 --> 00:07:18,576  
却非唯一忧虑。  
But it's not her only worry.  

78  
00:07:29,833 --> 00:07:32,142  
独狼现身。  
It's a lone wolf.  

79  
00:07:44,733 --> 00:07:48,276  
驯鹿的本能是保持移动。  
The caribou's instinct is to stay on the move.  

80  
00:07:48,300 --> 00:07:51,076  
总有一处比此地更安全。  
Somewhere has to be better than this.  

81  
00:07:56,800 --> 00:08:00,109  
但迁徙绝非盲目本能，  
But migration is not blind instinct,  

82  
00:08:00,133 --> 00:08:04,076  
而是基于天气模式与行程时间的微妙线索  
It's a series of collective decisions based on subtle clues  

83  
00:08:04,100 --> 00:08:07,876  
作出的群体决策。  
to weather patterns and journey times.  

84  
00:08:07,900 --> 00:08:10,066  
年年各异。  
Every year is different.  

85  
00:08:13,033 --> 00:08:15,709  
狼也面临抉择。  
The wolf has choices to make, too.  

86  
00:08:15,733 --> 00:08:19,276  
它可以尾随驯鹿，但鹿群行动迅捷，  
He can follow the caribou, but they move fast,  

87  
00:08:19,300 --> 00:08:21,500  
且路途过于遥远。  
and the journey is too far.  

88  
00:08:27,133 --> 00:08:30,009  
春日首个新生命降生。  
The first birth of spring.  

89  
00:08:30,033 --> 00:08:31,542  
并非驯鹿，  
It's not a caribou,  

90  
00:08:31,566 --> 00:08:35,842  
而是一头30磅重的麝牛幼崽，  
but a newborn musk ox, a 30-pound baby,  

91  
00:08:35,866 --> 00:08:39,809  
直接降临雪地。  
delivered straight onto the snow.  

92  
00:08:39,833 --> 00:08:42,009  
家族成员环绕守护，  
The family surrounds her,  

93  
00:08:42,033 --> 00:08:45,466  
抵御圈外危机。  
a protection from dangers outside their circle.  

94  
00:08:57,600 --> 00:09:02,642  
但数小时后，幼崽便渴望探索。  
But within hours, the calf wants out.  

95  
00:09:02,666 --> 00:09:05,366  
崭新世界等待发现。  
There's a beautiful new world to explore.  

96  
00:09:13,466 --> 00:09:16,309  
每头幼崽都弥足珍贵。  
Every calf is precious.  

97  
00:09:16,333 --> 00:09:19,209  
麝牛曾在1860年代  
Musk ox were hunted to extinction in Alaska  

98  
00:09:19,233 --> 00:09:21,009  
于阿拉斯加灭绝，  
in the 1860s,  

99  
00:09:21,033 --> 00:09:24,842  
1930年代被重新引入。  
but were brought back in the 1930s.  

100  
00:09:24,866 --> 00:09:28,166  
现仅存数千头于此地。  
There are now a few thousand here in Alaska.  

101  
00:09:32,900 --> 00:09:36,533  
小溪谷对幼崽而言是全新冒险。  
A little river gully is a new adventure for the calf.  

102  
00:09:42,000 --> 00:09:46,809  
一旦陷入，脱身更难。  
Once in, getting back out is harder.  

103  
00:09:58,700 --> 00:10:00,509  
母亲不会跟随。  
The mother won't follow.  

104  
00:10:00,533 --> 00:10:02,876  
她不知积雪深浅，  
She doesn't know how deep the snow is  

105  
00:10:02,900 --> 00:10:04,766  
恐遭困陷。  
and could easily get stuck.  

106  
00:10:08,700 --> 00:10:11,542  
她在岸边追踪幼崽踪迹。  
She tracks her calf from the bank.  

107  
00:10:20,466 --> 00:10:22,809  
幼崽发现了...  
The calf discovers...  

108  
00:10:22,833 --> 00:10:24,609  
冰面。  
ice.  

109  
00:10:44,366 --> 00:10:47,733  
在此立足需要身体上的紧迫感...  
There's a physical urgency to find your feet here...  

110  
00:10:50,500 --> 00:10:53,942  
...但幼崽认知世界的  
...but perhaps a greater mental urgency for the calf  

111  
00:10:53,966 --> 00:10:56,242  
精神需求更为迫切。  
to figure out her world.  

112  
00:11:00,300 --> 00:11:03,142  
母亲耐心守候...  
The patient mother waits...  

113  
00:11:03,166 --> 00:11:05,709  
幼崽终觅出路。  
and her calf finds a way out.  

114  
00:11:26,233 --> 00:11:28,342  
她还需照料幼崽  
She's got maybe another two years  

115  
00:11:28,366 --> 00:11:30,742  
约两年光景。  
looking after this youngster.  

116  
00:11:30,766 --> 00:11:34,209  
约十五头的族群将守护幼崽，  
The herd of about 15 will protect the calves  

117  
00:11:34,233 --> 00:11:38,966  
在广阔家园觅食直至夏日来临。  
and search for food around their large home range until summer.  

118  
00:11:49,300 --> 00:11:53,542  
驯鹿群已将冬季林地远远抛在身后，  
The caribou have left the winter woodland far behind,  

119  
00:11:53,566 --> 00:11:55,809  
向北挺进。  
and are heading north.  

120  
00:12:05,766 --> 00:12:08,609  
四月来临，积雪初融，  
By April, the snow is starting to melt,  

121  
00:12:08,633 --> 00:12:12,742  
众多河流解冻期较十年前提前。  
and many rivers run earlier than a decade ago.

122  
00:12:12,766 --> 00:12:17,976  
春日加速北移，驯鹿必须紧跟步伐。  
Spring is moving north faster, and the caribou need to keep up.  

123  
00:12:25,900 --> 00:12:29,242  
鹿群继续行进约百英里后，  
The herd heads on for about a hundred miles,  

124  
00:12:29,266 --> 00:12:30,909  
将转向西行，  
then will turn west  

125  
00:12:30,933 --> 00:12:33,942  
直指北极国家野生动物保护区。  
towards the Arctic National Wildlife Refuge.  

126  
00:12:39,166 --> 00:12:43,142  
四月尾声，迁徙已过半程。  
It's the end of April. They are over halfway.  

127  
00:12:43,166 --> 00:12:44,709  
母鹿们将在  
The mothers will all give birth  

128  
00:12:44,733 --> 00:12:47,576  
六月三日前后数日内分娩。  
within days of the third of June.  

129  
00:12:47,600 --> 00:12:49,233  
还剩六周。  
Six weeks to go.  

130  
00:12:57,666 --> 00:13:01,509  
金雕沿迁徙路线筑巢。  
Golden eagles nest along the route.  

131  
00:13:01,533 --> 00:13:03,042  
它们自南方北迁，  
They came up from the south  

132  
00:13:03,066 --> 00:13:05,776  
三月便划定领地，  
and established territories in March,  

133  
00:13:05,800 --> 00:13:09,600  
以野兔、雷鸟和旱獭为食。  
feeding on hares, ptarmigan, or marmots.  

134  
00:13:11,800 --> 00:13:17,542  
这对金雕每年重返同一处壮观的巢穴。  
The eagle pair returns to the same spectacular nest each year.  

135  
00:13:17,566 --> 00:13:22,476  
它们忠于十余年前选定的家园。  
They are loyal to a site decided over a decade ago.  

136  
00:13:22,500 --> 00:13:25,309  
但自然节律已今非昔比。  
But the calendar has changed a lot since then.  

137  
00:13:37,133 --> 00:13:40,376  
五月初，雏鹰即将离巢，  
By early May, the chicks are near fledging,  

138  
00:13:40,400 --> 00:13:43,633  
驯鹿群早已过境。  
and the caribou herd has already passed.  

139  
00:13:51,966 --> 00:13:54,700  
地松鼠成了早餐。  
A ground squirrel is breakfast.  

140  
00:14:07,333 --> 00:14:09,642  
适应此地的剧变，  
It will take a new generation of eagles  

141  
00:14:09,666 --> 00:14:13,833  
需待新一代金雕完成。  
to make the huge adjustment to the changes unfolding here.  

142  
00:14:17,300 --> 00:14:22,476  
独狼已尾随鹿群数十英里。  
A lone wolf has stuck with the herd for many miles.  

143  
00:14:40,033 --> 00:14:44,042  
加美边境两侧广袤区域的驯鹿  
Caribou from a broad area either side of the Canadian border  

144  
00:14:44,066 --> 00:14:46,709  
正汇聚于同一路线。  
are converging on the same route.  

145  
00:14:46,733 --> 00:14:50,342  
它们将绕行布鲁克斯山脉东端，  
They'll navigate around the eastern end of the Brooks Range,  

146  
00:14:50,366 --> 00:14:53,342  
距北极海岸约40英里处。  
about 40 miles from the Arctic shore.  

147  
00:15:06,566 --> 00:15:09,876  
少数地段的河湖周边  
In a few places, the route has bottlenecks  

148  
00:15:09,900 --> 00:15:12,242  
形成迁徙瓶颈。  
around rivers and lakes.  

149  
00:15:27,300 --> 00:15:31,442  
北极驯鹿迁徙堪比非洲草原的角马群，  
This migration of Arctic caribou is compared to wildebeest  

150  
00:15:31,466 --> 00:15:35,476  
因此这片海岸平原  
on the African savanna, and so the coastal plain  

151  
00:15:35,500 --> 00:15:39,576  
被誉为"美洲塞伦盖蒂"。  
is sometimes called America's Serengeti.  

152  
00:15:51,733 --> 00:15:53,909  
当鹿群穿过布鲁克斯山脉  
As the herd funnels through the foothills  

153  
00:15:53,933 --> 00:15:55,609  
山麓地带时，  
of the Brooks Range,  

154  
00:15:55,633 --> 00:15:58,800  
孤狼暂获优势。  
the wolf briefly gains an advantage.  

155  
00:16:08,600 --> 00:16:13,009  
去年诞下的孱弱幼鹿艰难跟随。  
The weaker calves from last year are struggling to keep up.  

156  
00:16:13,033 --> 00:16:15,442  
它们几乎无暇停歇进食。  
There's been little time to stop and eat.  

157  
00:16:22,533 --> 00:16:24,909  
只要鹿群保持警惕  
As long as the herd stays watchful  

158  
00:16:24,933 --> 00:16:28,076  
与安全距离，便可无恙。  
and maintains a distance, they're safe.  

159  
00:16:37,033 --> 00:16:39,909  
驯鹿速度更胜一筹。  
Caribou are faster.  

160  
00:16:39,933 --> 00:16:42,142  
孤狼虽擅战术，  
The wolf is a tactician,  

161  
00:16:42,166 --> 00:16:45,542  
独行却难施展。  
but tactics are hard if you work alone.  

162  
00:17:07,000 --> 00:17:11,009  
眼前是移动的饕餮盛宴，  
Here is an unparalleled amount of food on the hoof,  

163  
00:17:11,033 --> 00:17:15,309  
对孤狼而言却遥不可及。  
but to this lone wolf, it might as well not be here at all.  

164  
00:17:28,633 --> 00:17:33,576  
五月，春临北极野生动物保护区。  
By May, spring has reached the Arctic National Wildlife Refuge.  

165  
00:17:35,466 --> 00:17:39,800  
此地生灵已在雪下沉睡八个月。  
Life here has slept under snow for eight months.  

166  
00:17:44,566 --> 00:17:48,276  
鸻鸟与朱顶雀前来筑巢，  
Plovers and redpolls arrive to nest,  

167  
00:17:48,300 --> 00:17:51,033  
加入这场空中大迁徙。  
part of a massive aerial migration.  

168  
00:17:55,166 --> 00:17:59,276  
数百万雪雁告别加州与德州，  
Millions of snow geese leave California or Texas  

169  
00:17:59,300 --> 00:18:03,276  
飞往加拿大北极群岛，  
and are on their way to the Arctic Islands of Canada.  

170  
00:18:03,300 --> 00:18:06,209  
返程时将在此歇脚。  
They'll stop off here on their way back.  

171  
00:18:18,233 --> 00:18:21,609  
鹬鸟参与这场全球盛事。  
Sandpipers are part of the worldwide event.  

172  
00:18:27,566 --> 00:18:31,342  
金斑鸻自阿根廷启程。  
Golden plovers set off from Argentina.  

173  
00:18:31,366 --> 00:18:35,809  
燕鸥、潜鸟与鸣禽来自南极、  
Terns, loons, and songbirds come from Antarctica  

174  
00:18:35,833 --> 00:18:38,876  
非洲或东亚。  
or Africa or East Asia.  

175  
00:18:38,900 --> 00:18:41,909  
数百种鸟类横跨星球，  
Hundreds of species cross the planet  

176  
00:18:41,933 --> 00:18:44,442  
奔赴北极以北。  
on their way to the Arctic north.  

177  
00:18:58,166 --> 00:19:03,609  
全球飞鸟正飞向阿拉斯加的夏日天堂。  
A world of birds is heading to the summer paradise of Alaska.  

178  
00:19:15,900 --> 00:19:21,242  
金斑鸻夫妇在地面筑巢，  
The golden plover couple have arranged a nest on the ground,  

179  
00:19:21,266 --> 00:19:24,933  
产卵育雏。  
laid their eggs, and are raising their chicks.  

180  
00:19:38,233 --> 00:19:41,976  
双亲能抵御北极狐  
The parents provide some protection against Arctic foxes  

181  
00:19:42,000 --> 00:19:44,076  
与猛禽侵袭，  
or predatory birds,  

182  
00:19:44,100 --> 00:19:47,800  
但主要靠伪装羽翼下的体温守护。  
but it's mainly just warmth under a camouflaged wing.  

183  
00:19:58,533 --> 00:20:02,476  
解冻后的雏鸟须立即  
Once thawed out, the chicks have to get back to finding food  

184  
00:20:02,500 --> 00:20:04,133  
自行觅食。  
for themselves.  

185  
00:20:17,266 --> 00:20:20,242  
母亲两周后离去，  
The mother leaves after a couple of weeks,  

186  
00:20:20,266 --> 00:20:23,742  
父亲多留一周亦将启程。  
and the father follows a week or so later.  

187  
00:20:23,766 --> 00:20:25,976  
但雏鸟停留更久，  
But the chicks stay longer  

188  
00:20:26,000 --> 00:20:29,633  
需独自寻路返回南美。  
and have to find their own way back to South America.  

189  
00:20:32,600 --> 00:20:35,142  
其间雏鸟竭力捕捉昆虫，  
In the meantime, the chicks catch insects  

190  
00:20:35,166 --> 00:20:37,142  
直到力竭，  
for as long as they can,  

191  
00:20:37,166 --> 00:20:40,066  
再奔回父母身边取暖。  
then come running back to warm up again.  

192  
00:20:45,066 --> 00:20:48,542  
母亲深知威胁不止严寒。  
Their mother knows it's not just the cold that will get them.  

193  
00:21:00,833 --> 00:21:05,833  
北极狐栖居永冻层上方的地穴中。  
Arctic foxes live in tunnels in the layer above the permafrost.  

194  
00:21:11,100 --> 00:21:12,842  
数月前父母归来，  
The parents returned a few months ago  

195  
00:21:12,866 --> 00:21:17,376  
褪去雪白冬装，  
from their winter wanderings in snowy white coats  

196  
00:21:17,400 --> 00:21:20,533  
换夏棕产仔。  
to give birth and turn brown for summer.  

197  
00:21:30,533 --> 00:21:34,342  
幼崽五月初降生于此。  
The cubs were born here in early May.  

198  
00:21:34,366 --> 00:21:36,909  
如今数周过去，  
Now, a few weeks later,  

199  
00:21:36,933 --> 00:21:39,742  
尽享异常温暖的夏日。  
they enjoy the remarkably warm days.  

200  
00:22:02,466 --> 00:22:05,476  
它们需快速成长。  
They need to grow up fast.  

201  
00:22:05,500 --> 00:22:07,976  
幼崽已开始食肉，  
The cubs are already eating meat  

202  
00:22:08,000 --> 00:22:11,009  
饥肠辘辘似无底洞。  
and seem constantly hungry.  

203  
00:22:11,033 --> 00:22:13,642  
五六月的地松鼠与巢鸟  
Ground squirrels and nesting birds are here  

204  
00:22:13,666 --> 00:22:16,466  
数量庞大。  
in large numbers in May and June.  

205  
00:22:18,566 --> 00:22:21,242  
单次投喂远不足饱腹。  
One delivery is not enough for them all.  

206  
00:22:26,633 --> 00:22:29,342  
其余幼崽险些错过  
The others don't notice the mother's return  

207  
00:22:29,366 --> 00:22:31,376  
母亲归来。  
until it's almost too late.  

208  
00:22:52,566 --> 00:22:54,076  
也罢，  
Oh, well.  

209  
00:22:54,100 --> 00:22:56,076  
父亲很快会带回更多猎物。  
Dad will be back soon with more.  

210  
00:23:03,000 --> 00:23:05,942  
在这永昼时节，  
It's a constant meal service during days  

211  
00:23:05,966 --> 00:23:08,066  
喂食永不停歇。  
that never quite seem to end.  

212  
00:23:12,600 --> 00:23:15,909  
地面筑巢危机四伏，  
Nesting on the ground is dangerous,  

213  
00:23:15,933 --> 00:23:21,776  
唯有一种鸟能击退狐群——贼鸥。  
but there is one bird that would fight off any fox... the jaeger.  

214  
00:23:21,800 --> 00:23:24,500  
"贼鸥"德语意为"猎手"。  
Jaeger means hunter in German.  

215  
00:23:27,500 --> 00:23:30,642  
驯鹿群开始抵达。  
The caribou are beginning to arrive.  

216  
00:23:30,666 --> 00:23:36,076  
它们疲惫饥饿，临产在即，  
They are tired, hungry, many are about to give birth,  

217  
00:23:36,100 --> 00:23:39,533  
极易误踏鸟巢。  
and they could so easily tread on a bird's nest.  

218  
00:23:43,800 --> 00:23:47,176  
贼鸥绝不允此发生。  
The jaegers are not going to let that happen.  

219  
00:23:47,200 --> 00:23:50,009  
它们先以温和警告示之，  
They start with some gentle warnings,  

220  
00:23:50,033 --> 00:23:52,342  
驯鹿却置若罔闻。  
but the caribou ignore them.  

221  
00:23:56,533 --> 00:23:59,542  
贼鸥无所畏惧。  
Yet the jaegers are fearless.  

222  
00:24:18,133 --> 00:24:21,176  
驯鹿母亲跋涉数百英里，  
The caribou mother has come hundreds of miles,  

223  
00:24:21,200 --> 00:24:23,176  
闯激流、  
faced raging torrents,  

224  
00:24:23,200 --> 00:24:26,842  
越冰湖、避狼群，  
been jammed by lakes, escaped wolves,  

225  
00:24:26,866 --> 00:24:29,409  
如今却遭护巢心切的  
and now there's a determined parent bird  

226  
00:24:29,433 --> 00:24:31,509  
飞鸟驱逐。  
that doesn't want her here at all.  

227  
00:24:40,666 --> 00:24:44,642  
驯鹿以怪异舞步回应  
The caribou respond to the swooping bird ballet  

228  
00:24:44,666 --> 00:24:47,142  
俯冲的飞鸟。  
with strange dance moves of their own.  

229  
00:25:22,266 --> 00:25:24,376  
随着鹿群不断涌入，  
As more of the herd arrives,  

230  
00:25:24,400 --> 00:25:28,166  
贼鸥不知疲倦地守护卵巢。  
the jaegers battle tirelessly to keep their eggs safe.  

231  
00:25:30,233 --> 00:25:34,700  
对鸟类及此地众生而言，休憩皆是奢侈。  
For the birds, and for all life here, there's little rest.  

232  
00:25:37,100 --> 00:25:39,242  
就连太阳也持续运转，  
Even the sun keeps going,  

233  
00:25:39,266 --> 00:25:43,176  
六月大多时分都悬于地平线上。  
skimming above the horizon for most of June.  

234  
00:25:53,200 --> 00:25:56,276  
午夜阳光温暖着  
This midnight sun warms the caribou  

235  
00:25:56,300 --> 00:25:59,709  
终抵终点的驯鹿群。  
as they all finally reach their destination.  

236  
00:26:08,766 --> 00:26:11,176  
此处是它们的产犊地，  
These are their calving grounds,  

237  
00:26:11,200 --> 00:26:15,009  
北极国家野生动物保护区的核心地带。  
in the heart of the Arctic National Wildlife Refuge.  

238  
00:26:20,333 --> 00:26:24,709  
她必须精准抵达，才能在积雪融化后  
She must arrive precisely, so that she's in the right place  

239  
00:26:24,733 --> 00:26:27,442  
7至10天内身处莎草与牧草  
when, a week to 10 days after the snow melts,  

240  
00:26:27,466 --> 00:26:31,233  
营养最丰沛之地。  
the sedges and grasses are at their most nutritious.  

241  
00:26:33,666 --> 00:26:36,642  
某处正有新生命降生...  
Somewhere is a mother giving birth...  

242  
00:26:36,666 --> 00:26:44,042  
十六万幼崽中无名的一员，唯有彼此相认。  
one new calf among 160,000, anonymous to all but each other.  

243  
00:26:44,066 --> 00:26:48,276  
几乎所有母鹿都在数日内分娩。  
Almost all the mothers give birth within a few days.  

244  
00:26:58,866 --> 00:27:02,742  
幼崽两周内体型翻倍。  
The calf doubles in size in two weeks.

245  
00:27:02,766 --> 00:27:06,709  
莎草初绽的嫩芽短暂富含蛋白质  
The first green flush of sedges is briefly high in protein  

246  
00:27:06,733 --> 00:27:10,009  
与糖分，恰与幼鹿  
and sugars and coincides within a few days  

247  
00:27:10,033 --> 00:27:13,409  
哺乳高峰完美契合。  
of when the calf needs most milk.  

248  
00:27:13,433 --> 00:27:17,009  
约一周后，牧草将变得粗硬、  
A week or so later, the grass will become coarser,  

249  
00:27:17,033 --> 00:27:20,076  
苦涩且难消化。  
bitter, and indigestible.  

250  
00:27:27,533 --> 00:27:29,676  
驯鹿群逐渐分散，  
The caribou slowly spread out,  

251  
00:27:29,700 --> 00:27:34,242  
追逐融雪与新草生长的浪潮。  
surfing a wave of melting snow and growing grass.  

252  
00:27:43,333 --> 00:27:45,576  
充沛的能量补给  
The successful flood of energy  

253  
00:27:45,600 --> 00:27:48,842  
改变着驯鹿的体质。  
transforms the character of the caribou.  

254  
00:27:54,200 --> 00:27:57,342  
原住民自觉与之血脉相连。  
The first people here feel part of it.  

255  
00:27:57,366 --> 00:28:01,876  
他们相信人类与驯鹿本为同源，  
Humans and caribou were created as one, they believe,  

256  
00:28:01,900 --> 00:28:06,909  
至今彼此心魂相系。  
and each still contains a piece of each other's heart.  

257  
00:28:06,933 --> 00:28:10,042  
对格威迅人而言，此处是  
To the Gwich'in, this is the sacred place  

258  
00:28:10,066 --> 00:28:12,542  
生命起源的圣地。  
where life begins.  

259  
00:28:29,833 --> 00:28:35,809  
六月下旬，天堂突现危机。  
It's late June, and paradise suddenly closes in.  

260  
00:28:35,833 --> 00:28:39,509  
蚊虫大举来袭。  
A plague of mosquitoes emerges.  

261  
00:28:41,200 --> 00:28:44,876  
每只蚊子仅取一滴血，  
Each one may take just a drop of blood,  

262  
00:28:44,900 --> 00:28:48,909  
但温暖夏季助长虫群。  
but the warmer summers favor the insects.  

263  
00:28:48,933 --> 00:28:52,266  
它们更早苏醒，更快繁殖。  
They emerge earlier and breed faster.  

264  
00:29:02,000 --> 00:29:04,309  
蚊群疯狂吸血，  
The mosquitoes take so much blood  

265  
00:29:04,333 --> 00:29:07,276  
严重困扰母鹿，  
and distress the caribou mothers so much  

266  
00:29:07,300 --> 00:29:09,742  
迫使鹿群整个夏季  
that the herd spends the rest of the summer  

267  
00:29:09,766 --> 00:29:11,676  
都在寻觅凉爽之地  
attempting to avoid them  

268  
00:29:11,700 --> 00:29:14,942  
躲避侵扰。  
by searching for somewhere cooler.  

269  
00:29:14,966 --> 00:29:18,409  
生存变成每日在觅食  
Life becomes a daily balancing act of finding  

270  
00:29:18,433 --> 00:29:20,342  
与避蚊之间  
food for yourself  

271  
00:29:20,366 --> 00:29:24,642  
的艰难平衡。  
and not being food for mosquitoes.  

272  
00:29:24,666 --> 00:29:28,109  
炎夏对驯鹿的影响或许微妙复杂，  
The consequences of the hotter summers may be subtle  

273  
00:29:28,133 --> 00:29:30,809  
但在北方，  
and complex for the caribou,  

274  
00:29:30,833 --> 00:29:36,276  
变化更为显著。  
but the effects to the north are much more obvious.  

275  
00:29:36,300 --> 00:29:39,542  
过去40年间，波弗特海冰层消退  
Over the last 40 years, the decline of sea ice  

276  
00:29:39,566 --> 00:29:41,176  
堪称全球  
in the Beaufort Sea  

277  
00:29:41,200 --> 00:29:44,542  
最剧烈的变化之一。  
is one of the most dramatic changes anywhere.  

278  
00:29:51,733 --> 00:29:56,242  
北极熊首当其冲。  
One of the animals affected most is the polar bear.  

279  
00:29:56,266 --> 00:29:58,009  
冰河时期，  
During the last ice age,  

280  
00:29:58,033 --> 00:30:03,276  
它们可能终年栖息冰海。  
they would probably spend all year on the frozen sea.  

281  
00:30:03,300 --> 00:30:06,642  
冰期结束后，北极熊  
Since the ice age ended, polar bears hunted seals  

282  
00:30:06,666 --> 00:30:09,709  
冬春在冰面捕猎海豹，  
on the Arctic ice in winter and spring,  

283  
00:30:09,733 --> 00:30:12,409  
夏末登陆休憩，  
and in late summer, rested on land,  

284  
00:30:12,433 --> 00:30:15,642  
靠脂肪维持生存。  
snoozing and living off their fat.  

285  
00:30:23,300 --> 00:30:27,409  
如今波弗特海冰层变幻无常。  
Nowadays the ice on the Beaufort Sea is erratic.  

286  
00:30:27,433 --> 00:30:32,676  
加速消融迫使北极熊提前登陆且更消瘦。  
It melts faster, and the bears arrive early and thinner.  

287  
00:30:46,600 --> 00:30:51,609  
七月时，它们已沿岸觅食。  
By July, they are hunting for food along the shore.  

288  
00:30:51,633 --> 00:30:54,742  
对驯鹿群威胁有限——  
They're not a huge threat to the caribou herd.  

289  
00:30:54,766 --> 00:30:58,376  
陆上行动笨拙且易过热。  
They are lumbering on land, and easily overheat.  

290  
00:31:08,466 --> 00:31:10,809  
近年气候多变，  
Years are more variable now,  

291  
00:31:10,833 --> 00:31:14,776  
北极熊展现出惊人适应力：  
and polar bears are showing unexpected flexibility.  

292  
00:31:14,800 --> 00:31:16,876  
捕猎小型猎物、  
They search for smaller prey  

293  
00:31:16,900 --> 00:31:19,866  
争夺残羹腐肉。  
and scavenge or fight over scraps.  

294  
00:31:23,066 --> 00:31:25,709  
保护区虽是安全家园，  
The Arctic Refuge is a safe home,  

295  
00:31:25,733 --> 00:31:29,709  
却难挡外界剧变。  
but there is no refuge from the outside world.  

296  
00:31:29,733 --> 00:31:31,676  
酷暑难耐——  
It's too hot for them.  

297  
00:31:31,700 --> 00:31:35,800  
七月气温已创下85华氏度（29.4℃）纪录。  
The July record here is now 85 degrees Fahrenheit.  

298  
00:31:39,200 --> 00:31:41,766  
母熊最为艰辛。  
It's often hardest for a mother.  

299  
00:31:49,900 --> 00:31:53,842  
北极熊幼崽隆冬降生。  
Polar bear cubs are born in midwinter.  

300  
00:31:53,866 --> 00:31:58,076  
此海岸是北美最重要的  
This coast is one of the most important onshore denning areas  

301  
00:31:58,100 --> 00:31:59,733  
陆地育幼区之一。  
in North America.  

302  
00:32:05,333 --> 00:32:08,276  
这两只幼崽近两岁大，  
These cubs are almost two years old  

303  
00:32:08,300 --> 00:32:10,400  
仍需母乳喂养。  
but still need their mother's milk.  

304  
00:32:29,300 --> 00:32:33,909  
波弗特海南部北极熊数量锐减——  
Polar bears have declined in the southern Beaufort Sea.  

305  
00:32:33,933 --> 00:32:37,833  
较35年前减少约半数。  
There are about half of how many were here 35 years ago.  

306  
00:32:43,633 --> 00:32:46,342  
这是绝望的年代。  
These are desperate times.  

307  
00:32:53,033 --> 00:32:57,842  
北阿拉斯加拥有美国最大油田。  
North Alaska has the largest oil field in America.  

308  
00:33:08,366 --> 00:33:11,342  
普拉德霍湾基地毗邻  
The base at Prudhoe Bay is next to  

309  
00:33:11,366 --> 00:33:14,542  
北极国家野生动物保护区，  
the Arctic National Wildlife Refuge.  

310  
00:33:14,566 --> 00:33:16,176  
赤裸昭示着  
It's a stark reminder  

311  
00:33:16,200 --> 00:33:19,009  
季节变迁的根源。  
of the cause of the changing seasons.  

312  
00:33:31,133 --> 00:33:33,909  
输油管道向南延伸，  
Pipelines extend south  

313  
00:33:33,933 --> 00:33:37,509  
横穿数条驯鹿迁徙路线。  
and cross several caribou migration routes.  

314  
00:33:46,033 --> 00:33:49,309  
北极熊在石油勘探  
The polar bears search for food across land  

315  
00:33:49,333 --> 00:33:52,576  
伤痕累累的土地觅食。  
now scarred by oil exploration.  

316  
00:34:11,333 --> 00:34:14,942  
驯鹿的新草盛宴结束，  
For the caribou, the green surge is over,  

317  
00:34:14,966 --> 00:34:16,809  
改食柳灌木丛，  
and they are eating willow shrub  

318  
00:34:16,833 --> 00:34:21,776  
寻觅凉爽无蚊之地。  
and searching for anywhere cooler and mosquito free.  

319  
00:34:21,800 --> 00:34:25,009  
部分前往海岸，  
For some, that means the coast.  

320  
00:34:25,033 --> 00:34:29,342  
另一些南赴布鲁克斯山麓。  
Others head south into the foothills of the Brooks Range.  

321  
00:34:37,200 --> 00:34:42,200  
熬过七月酷暑，八月末终得清凉。  
After enduring the heat of July, by late August, it's cooler.  

322  
00:34:49,900 --> 00:34:54,333  
母鹿携幼在鹿群护卫下南归。  
A mother and calf turn south, with the protection of the herd.  

323  
00:34:57,166 --> 00:35:01,642  
等待它们的是灰熊。  
Waiting for them is a grizzly.  

324  
00:35:01,666 --> 00:35:04,566  
灰熊与驯鹿年年相遇。  
Grizzlies and caribou meet each year.  

325  
00:35:07,200 --> 00:35:11,066  
鹿群以必经的豪猪河命名。  
The herd is named after the Porcupine River they must cross.  

326  
00:35:19,700 --> 00:35:24,042  
灰熊的征程同样危机四伏。  
The bear's journey here is equally hazardous.  

327  
00:35:24,066 --> 00:35:28,500  
夏季灰熊的猎场直达北冰洋。  
In summer, grizzlies hunt all the way to the Arctic Ocean.  

328  
00:36:00,033 --> 00:36:02,409  
豪猪驯鹿群  
The Porcupine caribou herd  

329  
00:36:02,433 --> 00:36:05,133  
南向进入布鲁克斯山脉。  
is heading south into the Brooks Range.  

330  
00:36:13,566 --> 00:36:17,333  
远离水域后，驯鹿逐渐放松。  
Away from the water, the caribou start to relax.  

331  
00:36:21,466 --> 00:36:23,076  
这是致命错误。  
It's a mistake.  

332  
00:36:36,000 --> 00:36:39,909  
平原上驯鹿虽快过灰熊，  
Caribou may be faster than bears on the open plain,  

333  
00:36:39,933 --> 00:36:42,776  
但幼鹿需要休憩。  
but they must also rest the calves.  

334  
00:36:48,700 --> 00:36:52,409  
灰熊与北极熊近乎同种，  
Grizzlies and polar bears are almost the same species  

335  
00:36:52,433 --> 00:36:55,776  
活动范围重叠且频繁杂交，  
and increasingly overlap and interbreed,  

336  
00:36:55,800 --> 00:36:59,433  
但灰熊对鹿群威胁更大。  
but grizzlies are a more serious threat to the herd.  

337  
00:37:01,700 --> 00:37:05,376  
这头灰熊学会驱散母鹿，  
The bear has learned to chase off the mothers  

338  
00:37:05,400 --> 00:37:08,776  
再搜捕灌丛中的幼鹿。  
and then search for calves hiding in the scrub.  

339  
00:37:24,133 --> 00:37:25,833  
它发现两只幼崽。  
He's found two.  

340  
00:37:28,200 --> 00:37:31,676  
犹豫刹那...  
In a moment of indecision...  

341  
00:37:31,700 --> 00:37:33,300  
错失两者。  
he loses both.  

342  
00:37:37,666 --> 00:37:40,976  
幼鹿母亲疾驰护崽。  
The calf's mother gallops to his side.  

343  
00:37:41,000 --> 00:37:44,876  
历经万难后的伟大胜利。  
It's a huge victory after so much hardship.  

344  
00:37:52,366 --> 00:37:54,000  
灰熊则徒劳无功。  
Though not for the bear.  

345  
00:38:02,633 --> 00:38:06,909  
南归之路秋越布鲁克斯山脉。  
The journey south crosses the Brooks Range in fall.  

346  
00:38:06,933 --> 00:38:10,609  
春日此路被雪阻断，  
In spring, this route is blocked by snow,  

347  
00:38:10,633 --> 00:38:13,809  
如今可直穿山峦。  
but now they can return straight over the mountains.  

348  
00:38:41,766 --> 00:38:46,409  
幼鹿初探广袤世界，  
For the calf, this is his first taste of the wider world,  

349  
00:38:46,433 --> 00:38:50,709  
邂逅新朋友——白大角羊。  
with some new characters... Dall sheep.  

350  
00:38:58,466 --> 00:39:03,076  
它们是大角羊的近亲，  
They are cousins of bighorns, little bighorns,  

351  
00:39:03,100 --> 00:39:05,133  
山地生存专家。  
and mountain specialists.  

352  
00:39:08,766 --> 00:39:11,309  
如麝牛般不迁徙，  
Like musk ox, they don't migrate,  

353  
00:39:11,333 --> 00:39:14,409  
但会在山间寻觅  
but they do move around the mountains looking for grass  

354  
00:39:14,433 --> 00:39:17,942  
岩缝间的草料灌木。  
and shrubs between the rocks.  

355  
00:39:17,966 --> 00:39:22,109  
母羊五月底产单胎，  
The ewes give birth to a single lamb in late May.  

356  
00:39:22,133 --> 00:39:26,509  
九月时共沐残夏。  
By September, they are all enjoying the last of the summer.  

357  
00:39:43,566 --> 00:39:49,676  
母羊群聚警戒狼与金雕。  
The mothers gather in flocks and watch for wolves and eagles.  

358  
00:39:49,700 --> 00:39:52,176  
这条南迁路线，  
This is the migration route south,  

359  
00:39:52,200 --> 00:39:54,809  
不仅驯鹿熟知。  
familiar to more than just caribou.  

360  
00:40:16,300 --> 00:40:18,242  
初长成的金雕  
The fledged golden eagle  

361  
00:40:18,266 --> 00:40:22,876  
一路追随驯鹿群南行。  
has been shadowing the caribou herd south.  

362  
00:40:22,900 --> 00:40:24,842  
当鹿群东转，  
As the herd turns east,  

363  
00:40:24,866 --> 00:40:28,176  
将直面山狼威胁。  
the caribou face the mountains' wolves.  

364  
00:40:33,333 --> 00:40:37,533  
小山谷中，鹿群缓行休整。  
In a small valley, the herd slows to rest.  

365  
00:40:42,133 --> 00:40:45,266  
孤狼母狼谋划猎袭。  
A lone female plans her hunt.  

366  
00:40:51,366 --> 00:40:53,276  
它无意隐藏。  
She doesn't try to hide.

367  
00:40:53,300 --> 00:40:55,976  
此刻群山是她的盟友。  
The mountains are on her side now.  

368  
00:41:19,500 --> 00:41:22,476  
一只幼鹿落单。  
A calf becomes separated.  

369  
00:41:39,833 --> 00:41:41,209  
对它的母亲而言，  
To its mother,  

370  
00:41:41,233 --> 00:41:46,366  
这场近乎抵达终点的跋涉已失去意义。  
almost home, the trek has lost its meaning, its purpose.  

371  
00:41:54,333 --> 00:42:00,409  
雪雁从最北端的北极群岛抵达此地。  
The snow geese arrive here from the northernmost Arctic islands.  

372  
00:42:00,433 --> 00:42:04,576  
这是它们返回加州、德州  
This is an important stopover on their way back to California,  

373  
00:42:04,600 --> 00:42:07,176  
与墨西哥的重要中转站。  
Texas, and Mexico.  

374  
00:42:11,966 --> 00:42:16,509  
过去20年雪雁数量增长，  
Snow geese numbers have grown over the last 20 years.  

375  
00:42:16,533 --> 00:42:18,709  
现达两千万只。  
There are now 20 million of them.  

376  
00:42:24,266 --> 00:42:26,642  
在物种衰退的当下，  
In a world of so much decline,  

377  
00:42:26,666 --> 00:42:29,876  
某些物种的繁荣令人欣慰。  
it's good to know some species are doing well.  

378  
00:42:55,766 --> 00:42:59,976  
秋日风暴席卷而来。  
The autumn storms are sweeping in.  

379  
00:43:00,000 --> 00:43:02,576  
天气瞬息万变。  
The weather changes very quickly.  

380  
00:43:14,700 --> 00:43:18,876  
雷鸟还披着夏羽，  
Ptarmigans have been caught in their summer plumage.  

381  
00:43:18,900 --> 00:43:21,966  
换羽周期已然失调。  
They'll turn white to an out-of-date schedule.  

382  
00:43:26,033 --> 00:43:28,742  
只要积雪不深，  
As long as the snow isn't too deep,  

383  
00:43:28,766 --> 00:43:31,976  
它们能以柳芽桦枝为食。  
they can feed on willow buds and birch.  

384  
00:43:39,100 --> 00:43:41,909  
雷鸟常年栖息于此，  
Ptarmigans are here all year.  

385  
00:43:41,933 --> 00:43:46,276  
成为赤狐稳定的猎物来源。  
That makes them a reliable target for a red fox.  

386  
00:44:02,366 --> 00:44:05,642  
群体的众多眼睛  
The many eyes of a flock  

387  
00:44:05,666 --> 00:44:09,133  
与尖锐鸣叫暂时形成保护。  
and their sharp calls protect them for now.  

388  
00:44:11,400 --> 00:44:14,042  
赤狐在北极繁衍生息，  
Red foxes are thriving in the Arctic  

389  
00:44:14,066 --> 00:44:18,442  
气候变暖时更胜北极狐一筹。  
and out-compete Arctic foxes if the weather is milder.  

390  
00:44:34,466 --> 00:44:37,642  
十月时河流封冻，  
By October, the rivers are frozen  

391  
00:44:37,666 --> 00:44:39,376  
覆没雪下。  
and are buried under snow.  

392  
00:44:46,833 --> 00:44:50,476  
麝牛再次刨雪觅食。  
The musk ox have to dig for vegetation again.  

393  
00:44:57,300 --> 00:45:01,309  
雄性麝牛另有要务。  
The male musk ox have other concerns.  

394  
00:45:01,333 --> 00:45:03,009  
寒冬降临前，  
Before winter arrives,  

395  
00:45:03,033 --> 00:45:06,276  
必须决出交配权。  
they must sort out mating rights to the harem.  

396  
00:45:06,300 --> 00:45:08,376  
八月开始的争霸战  
The rut started in August  

397  
00:45:08,400 --> 00:45:11,109  
至今未决胜负。  
and a clear victor has yet to emerge.  

398  
00:46:03,166 --> 00:46:07,176  
麝牛与大角羊同源，  
The musk ox are also related to bighorn sheep,  

399  
00:46:07,200 --> 00:46:09,142  
体型却庞大得多。  
but are much bigger.  

400  
00:46:09,166 --> 00:46:11,909  
雄性重达800磅（363公斤），  
Males weigh in at 800 pounds,  

401  
00:46:11,933 --> 00:46:16,576  
冲锋时速近60英里（96公里）。  
and their closing speed is close to 60 miles an hour.  

402  
00:46:16,600 --> 00:46:19,442  
头骨异常坚固，  
Their skulls are heavily reinforced  

403  
00:46:19,466 --> 00:46:22,176  
脑部有液体保护。  
and the brain protected by fluid.  

404  
00:46:35,466 --> 00:46:39,742  
后撤只为蓄力再战。  
They back away, but only to prepare for combat.  

405  
00:46:46,266 --> 00:46:49,609  
右侧年长者静待时机，  
On the right, the older waits,  

406  
00:46:49,633 --> 00:46:51,776  
骤然冲锋。  
then charges.  

407  
00:47:04,400 --> 00:47:07,142  
地球上或许没有其他生物  
There's probably no other animal on Earth  

408  
00:47:07,166 --> 00:47:09,133  
能承受这种撞击。  
that could survive this battle.  

409  
00:47:12,366 --> 00:47:15,076  
胜者将获得族群交配权。  
The winner will now mate with the herd.  

410  
00:47:21,100 --> 00:47:25,742  
十月大地彻底封冻。  
By October, the land is frozen solid.  

411  
00:47:28,933 --> 00:47:32,242  
两只北极熊幼崽在母亲庇护下  
Two polar bear cubs have survived the summer  

412  
00:47:32,266 --> 00:47:34,009  
熬过夏季。  
thanks to their mother.  

413  
00:47:44,033 --> 00:47:46,776  
海域全面封冻要待十一月，  
The sea won't freeze solid until November,  

414  
00:47:46,800 --> 00:47:52,109  
但部分海湾河口先行结冰。  
but some coastal bays and river estuaries freeze earlier.  

415  
00:47:52,133 --> 00:47:56,266  
成为等待期间的游乐场。  
It's their playground while they wait.  

416  
00:47:59,433 --> 00:48:01,176  
暖日里冰面融化，  
On warm days the surface  

417  
00:48:01,200 --> 00:48:04,809  
变得湿滑脆弱——  
starts to melt and becomes slippery  

418  
00:48:04,833 --> 00:48:08,176  
潮汐削弱新冰，  
and tides weaken the new ice.  

419  
00:48:08,200 --> 00:48:11,076  
冰层仍不稳固。  
The surface is still fragile.  

420  
00:48:32,133 --> 00:48:35,642  
深冬时节，它们将在远离陆地的寒暮中  
By midwinter, they'll be sniffing out seals  

421  
00:48:35,666 --> 00:48:39,042  
嗅探海豹踪迹。  
in a freezing twilight far from land.  

422  
00:48:45,033 --> 00:48:48,976  
这终是它们的冰河家园，  
This is their ice age home at last,  

423  
00:48:49,000 --> 00:48:53,642  
永恒的景象遗世于剧变之外。  
a timeless scene that leaves behind a world of change.  

424  
00:49:01,800 --> 00:49:06,233  
冰层破裂，现实回归。  
Then the ice breaks, and reality returns.  

425  
00:49:19,466 --> 00:49:21,876  
海冰消融复冻，  
The sea melts and refreezes  

426  
00:49:21,900 --> 00:49:25,876  
还将经历两个月的反复。  
and will melt again for two frustrating months.  

427  
00:49:35,300 --> 00:49:38,942  
波弗特海南部的北极熊  
The polar bears of the southern Beaufort Sea are doing better  

428  
00:49:38,966 --> 00:49:42,609  
比多数北极同胞幸运。  
than many others around the Arctic.  

429  
00:49:55,033 --> 00:49:59,176  
保护区守护着它们的巢穴，  
The Arctic National Wildlife Refuge protects the dens,  

430  
00:49:59,200 --> 00:50:03,409  
母熊也成了娴熟的清道夫。  
and mothers have become expert scavengers.  

431  
00:50:03,433 --> 00:50:08,476  
它们的嗅觉或是动物界最敏锐的。  
Their sense of smell is probably the best of all animals.  

432  
00:50:26,933 --> 00:50:29,076  
看它们的发现——  
And look what they've found.  

433  
00:50:35,200 --> 00:50:39,042  
一头弓头鲸的残骸。  
It's a bowhead whale... What's left of it.  

434  
00:50:43,966 --> 00:50:46,842  
面对变幻莫测的冰情，  
With unpredictable winter ice ahead,  

435  
00:50:46,866 --> 00:50:50,742  
这具鲸骸成了北极熊家族  
this bowhead carcass is a salvation for the family  

436  
00:50:50,766 --> 00:50:54,376  
与当地所有北极熊的救赎。  
and for all the local polar bears.  

437  
00:50:54,400 --> 00:50:56,733  
足够数周饱食。  
They will feed for weeks.  

438  
00:50:58,533 --> 00:51:04,242  
弓头鲸数量增长或受益于夏季延长。  
Bowhead whales are increasing, maybe thanks to longer summers.  

439  
00:51:04,266 --> 00:51:07,833  
万物皆变，万物相连。  
Everything is changing, and everything is connected.  

440  
00:51:10,366 --> 00:51:13,042  
当地鲸猎受严格管制，  
There is regulated whale hunting here,  

441  
00:51:13,066 --> 00:51:15,042  
这具鲸骸实为  
and this carcass has actually been left  

442  
00:51:15,066 --> 00:51:17,600  
刻意留给野生动物的馈赠。  
on the beach for the wildlife.  

443  
00:51:19,800 --> 00:51:22,542  
对北极熊是生命线，  
For the polar bears, it's a lifeline,  

444  
00:51:22,566 --> 00:51:24,200  
却也仅此而已。  
but maybe little more.  

445  
00:51:26,500 --> 00:51:29,942  
它们是冰原之子，属于另一个世界。  
They are ice bears, evolved in another world.  

446  
00:51:35,800 --> 00:51:40,209  
数百万年来，地球历经  
Across millions of years, the Earth has seen huge changes  

447  
00:51:40,233 --> 00:51:42,476  
无数次剧变。  
many times.  

448  
00:51:42,500 --> 00:51:47,542  
最近一次是一万两千年前的冰河时代终结。  
The most recent was the end of the Ice Age, 12,000 years ago.  

449  
00:51:54,966 --> 00:51:56,742  
这片非凡的荒野  
This extraordinary wilderness  

450  
00:51:56,766 --> 00:52:00,142  
庇护着冰河时代的遗民——  
protects these Ice Age survivors...  

451  
00:52:00,166 --> 00:52:04,076  
北极熊、麝牛、北极狐，  
The polar bears, musk ox, arctic foxes,  

452  
00:52:04,100 --> 00:52:06,409  
以及壮观的驯鹿群，  
and the spectacular caribou,  

453  
00:52:06,433 --> 00:52:10,842  
在世界之巅坚守至今。  
holding out on the top of the world.  

454  
00:52:10,866 --> 00:52:15,342  
如今即便对它们而言，冰河时代  
Now, even for them, the ice age may, finally,  

455  
00:52:15,366 --> 00:52:17,209  
或许终将落幕。  
be coming to an end.  

456  
00:52:57,766 --> 00:53:01,209  
欲了解更多本期《自然》节目内容，  
To learn more about what you've seen on this "Nature" program,  

457  
00:53:01,233 --> 00:53:03,209  
请访问pbs.org。  
visit pbs.org.