What could have caused the crows to caw?

什么能让乌鸦叫的？

I never saw a boy foxes and crows loved.

我还从没见过能让狐狸和乌鸦喜欢的男孩呢。

At dawn, the crows flew back to their lair.

天亮了，乌鸦飞回了他们的巢穴。

The cock crows and the dawn chorus begins.

公鸡叫了,众鸟的清晨鸣唱随之开始了。

The researchers hypothesize that crows learn to recognize threatening humans from both parents and others in their flock.

研究人员猜测，这些乌鸦从父母和鸦群的其它成员那里学会了辨认有威胁的人类。