我们的星球（2019）

With things getting dangerous
‎这些雏雁是时候开始迁徙生活了
it's time for these chicks to start their life on the move.
‎一家人朝着安全的水域前进
The family heads for the safety of the water.
‎短短八周内 当这里的日照开始减弱
In just eight weeks, when the sun's power starts to wane here
‎小雁们会进行第一次南飞
the goslings will make their first flight south
‎一直到墨西哥湾
all the way to the Gulf of Mexico.
‎（墨西哥湾）
‎并不是所有动物都会随季节迁徙
Not all animals migrate as the seasons change.
‎狮子年复一年地控制着同一个领地
Lions control the same territory year in, year out.
‎所以东非塞伦盖蒂平原上的骄傲 ‎依靠的是猎物主动送上门来
So this pride in East Africa's Serengeti relies on prey coming to them.
‎现在正值旱季的高峰期
Right now, it's the height of the dry season
‎这些狮子生活的长草平原
and the long grass plains where these lions live
‎相对空旷
are relatively empty.
‎但情况马上就要改变了
But things are about to change.
‎成千上万匹牛羚正在朝它们行进
Heading towards them are hundreds of thousands of wildebeest.
‎它们共同构成了地球最大的陆地迁徙
Together, they make up the biggest terrestrial migration on Earth.
‎牛羚群每天要吃掉近五千吨♥的牧草
The herd eats its way through nearly 5,000 tons of grass a day
‎这意味着它们必须不断移♥动♥
which means they have to keep on the move.
‎这是狮子一直在指望的东西
Something the lions have been counting on.
‎长干草没有什么营养价值
The long dry grass is of little nutritional value
‎但牛羚群必须经过这片草原
but the herd must pass through it.
‎狮子们知道这一点
And the lions know that.
‎长草提供了非常有效的隐身斗篷
The grass provides a very effective cloak of invisibility.
‎为了防止自己的气味被发现
To prevent her scent being detected
‎母狮从下风处接近
the lioness approaches from downwind.
‎跟踪
Stalking.
‎潜伏
And stopping.
‎每一个动作
Every movement
‎都经过考虑
considered.
‎稍不小心 就会暴露行迹
One careless step could reveal her presence.
‎草丛中的任何动静
Any disturbance in the grass
‎都可能是对牛羚群的潜在威胁
could be a potential threat for the herd.
‎那只是一只珍珠鸡
That's just a guinea fowl.
‎假警报
A false alarm.
‎也许并不尽然
Or... perhaps not.
‎它的位置几乎完美
She's almost perfectly placed.
‎距离它的目标只有20米
Just 20 meters from her target.
‎数月缺少食物 这一餐事关生死
After months with little to eat, this is a vital meal.
‎骄傲的狮子 ‎必须在迁徙的牛羚群经过之时
The pride will need to make the most of the migration
‎充分捕食猎物
while it's passing through.
‎牛羚群很快就会离开狮子们的领地
Soon, the herds will have left the lions' territory
‎向北移♥动♥ 永无止境地寻找新鲜牧草
moving north in their never-ending search for fresh grazing.
‎（八月）
‎八月是北半球最温暖的时期
In August, the Northern Hemisphere is at its warmest.
‎在加拿大的温哥华岛上
And on Canada's Vancouver Island
‎有一种动物的生命周期 ‎依赖于较高的温度
there's one animal whose life cycle depends on these higher temperatures.
‎当雪松湖破晓时
As day breaks over Cedar Lake
‎湖水深处有东西在骚动
something is stirring in its depths.
‎这里的小蝌蚪夜间躲在凉爽的深水中
Tadpoles here spend their nights hiding in deep, cool water.
‎现在太阳升起了 它们开始穿越湖水
Now, with the sun up, they set off across the lake.
‎最初是几百只
Initially, in hundreds.
‎然后是成千上万
Then thousands.
‎所有蝌蚪都在前往阳光普照的浅滩
All are heading for the sunlit shallows.
‎这里的水温比湖底深处高出五度
Here, the water is five degrees warmer than in the lake's depths
‎这会加速它们向蟾蜍的转变
and that will speed their transformation into toads.
‎但当夜幕降临
But when night falls
‎它们会回到安全的湖水深处
they head back to the safety of the deep.
‎直到第二天早上
Until the next morning.
‎它们每天都在重复这样的旅程
Every day they repeat the journey.
‎太阳
Sun.
‎游泳
Swim.
‎进食
Feed.
‎重复
Repeat.
‎看起来很完美
It seems perfect.
‎只是有其它动物 ‎会利用它们的日常活动
Except others take advantage of their daily routine.
‎蜻蜓幼虫
Dragonfly larvae.
‎它们是埋伏的捕食者
They are ambush predators
‎有着可延伸的下颚
with extendable jaws.
‎而且它们的食欲旺盛
And they have voracious appetites.
‎无眼的水蛭在泥泞的滩底巡逻
Blind leeches patrol the muddy bottom.
‎一旦它们抓到什么…
Once they catch something...
‎就会将血吸干
they suck out its blood.
‎整个夏天
Throughout the summer
‎蝌蚪们不断进行它们的日常通勤
the tadpoles continue their daily commute.
‎直到几周后…
Until, after a few weeks...
‎它们开始有小蟾蜍的样子了
...they start to look like tiny toads.
‎通过利用太阳的能量 它们迅速成长
By harnessing the sun's energy, they've grown quickly.
‎现在 它们停止了日常通勤
Now, they stop their daily routines
‎为进入森林的旅程做准备了
and prepare for their journey into the forest.
‎在这里
Here too
‎同样潜伏着捕食者
predators await.
‎束带蛇专门吃两栖动物
Garter snakes specialize in eating amphibians.
‎不过它们很少有这么多选择
Though they rarely have as much choice as this.
‎说到底 小蟾蜍的数量还是超过蛇的
Eventually, the sheer numbers of young toads overwhelm the snakes.
‎幸存者散布在森林中
The survivors spread out into the forest
‎它们会在那里度过接下来的四年
where they'll spend the next four years.
‎直到轮到它们回到湖中繁殖
Until it's time for them to head back to the lake to breed.
‎仲夏时节 美国太平洋 ‎西北地区的积雪已经所剩无几
By midsummer, there is little snow left in America's Pacific Northwest.
‎融化的雪水填满河道
Meltwater fills the rivers
‎随时准备承载旅行者
ready to carry travelers who make what is perhaps
‎开启一段或许可谓最为不寻常
the most extraordinary and demanding journey
‎也是最艰难的旅程
tackled by any animal.
‎红鲑鱼
Sockeye salmon.
‎它们正在往上游♥行♥进 准备繁殖
And they're heading upriver to breed.
‎在白令海捕食三年后
After three years feeding in the Bering Sea
‎它们会穿越几百公里的海洋
they find their way across hundreds of kilometers of ocean
‎由地球的磁场引导
guided by the Earth's magnetic field
‎利用它们识别河流味道的惊人能力
and their astounding ability to recognize the taste of the river
‎辨认出孵化它们的河流
in which they hatched.
‎它们是世界上少数 ‎能够从盐水中进入淡水的鱼类之一
They are one of the few fish in the world that can move from saltwater into fresh.
‎在接下来的一个月里
And over the next month
‎它们将逆流而上两百公里
they will travel 200 kilometers upstream
‎经过伊利亚纳湖 到达它们的产卵池
past Lake Iliamna, to their spawning pools just beyond.
‎这是这些鲑鱼最后的旅程
It's the last journey these salmon will ever make.
‎当它们进入河流之后 会停止进食…
As they enter the river, they stop eating...
‎把所有的精力都放在与水流搏斗上
putting all their efforts into battling the current.
‎湍急的激流和高高的瀑布 ‎并不能阻止它们
Swift rapids and high waterfalls do not stop them.
‎踏上旅程四周后
Four weeks into their journey
‎它们的身体开始改变
their bodies begin to change.
‎侧身出现红色
Flashes of red appear in their flanks.
‎这是它们的繁殖色
These are their breeding colors.
‎鲑鱼的颜色越红 就越强壮
And the redder the fish, the fitter they are.
‎几周之后 它们几乎完全变样了
A few more weeks, and they're barely recognizable.
‎雄性的下巴已经变成了钩状的喙
The jaws of the males have become hooked beaks
‎它们会用这种喙来争夺配偶
which they will use to fight for a mate.
‎但是它们的产卵池还在近一百公里外
But their spawning pools are still nearly 100 kilometers away.
‎上游处
And just upriver
‎潜伏着准备拦截它们的捕食者
there are predators ready to intercept them.
‎熊依靠每年的鲑鱼洄游
Bears depend on the annual salmon run
‎为即将到来的冬天增肥
to fatten up for the winter ahead.
‎现在它们饿极了
And right now, they're very, very hungry.
‎在迁徙季中
During the migration
‎一头成年熊每天可以吃40条鲑鱼
an adult bear can eat 40 salmon a day.
‎鲑鱼快速且敏捷
The salmon are quick and agile.
‎但随着河水变浅…
But, as the water gets shallower...
‎熊逐渐占据优势
the advantage swings in favor of the bears.
‎再往上游数公里
Several kilometers upstream
‎鲑鱼们终于到达伊利亚纳湖
the fish finally reach Lake Iliamna.
‎美国仅剩的几条原始水道之一
One of the last pristine waterways in America.
‎它们的产卵池就在上游处
Their spawning pools lie just upstream.
‎但目前 红鲑鱼还在逗留
But, for now, the sockeye linger
‎等待雌鱼的卵子完成发育