历史上，很多民族因为战争或气候变化被迫大规模迁徙。

Lìshǐ shàng, hěn duō mínzú yīnwèi zhànzhēng huò qìhòu biànhuà bèipò dàguīmó qiānxǐ.

In history, many peoples were forced to migrate on a large scale because of war or climate change.

每年冬天，许多候鸟都会从北方迁徙到温暖的南方。

Měinián dōngtiān, xǔduō hòuniǎo dōu huì cóng běifāng qiānxǐ dào wēnnuǎn de nánfāng.

Every winter, many migratory birds move from the north to the warm south.

科学家在研究动物迁徙路线时，会给它们戴上可以定位的环。

Kēxuéjiā zài yánjiū dòngwù qiānxǐ lùxiàn shí, huì gěi tāmen dàishàng kěyǐ dìngwèi de huán.

When studying animals' migration routes, scientists put rings on them that can be tracked.