You also travel with a flock of migrating birds.

你还随着一群的鸟到处旅行。

These are migrations that have been compared to migrations on the Serengeti in Africa.

“这些与非洲塞伦盖蒂平原上的大相提并论。

It's one of nature's most spectacular mass migrations.

黑脉金斑蝶的是自然界最壮观的大规模之一。

But for many migrants-like smaller songbirds-nighttime is the right time, when it comes to migration.

但是，对于小型鸣禽等众多动物而言，夜晚才是适合的时间。

And why go north for the winter when most migrants move south?

为什么当大部分的动物向南部过冬时他却向北部？

Vertical migration in the ocean is the largest net animal movement on our planet.

海洋中的垂直是地球上最大的动物净。

And they seem to be migrating north.

乎正在向北。

You are now ready for the great migration.

准备好开始大吧。

The result: a large-scale polar bear treadmill. And all that walking requires extra fuel.

大批北极熊徒步。而这种需要额外的能量。

The birds are migrating at night.

鸟儿在夜间。

We have the right to move freely in our own countries.

人人在各国境内有权自由。

Meadow-larks migrate but a very short distance.

草地云雀的距离很短。

Many birds will often migrate just to find food.

许多鸟类经常只是为了寻找食物。

It is one of the largest migrations of fish in the world.

这是世界上最大的鱼类之一。

Mountain bongos once moved in large numbers.

山地紫羚曾经成群结队地。

The Coa Valley provides a migratory corridor for rare species.

科阿山谷为稀有物种提供了通道。

The Coa Valley provides a migratory corridor for rare species.

科阿山谷为稀有物种提供了通道。

20. Where do monarch butterflies settle at the end of the migration?

20。帝王蝶在的最后会安顿在哪里？

The tribe's forceful removal began in the late 19th century.

该部落的强行始于19世纪末。

The count down to their autumn migration has already begun.

秋季的已经开始了倒计时。