Then they identified begging calls by analyzing the order and number of notes.

然后，他们通过分析音符的顺序和数量来识别求食的叫声。

And the more frequently mothers had called to their eggs, the more similar were the babies' begging calls.

母亲对鸟蛋鸣叫的频率越高，雏鸟的求食声就越相似。

But, perhaps because it hatched sooner, the cuckoo chick wasn't able to learn the password, and so it doesn't croon the right begging call.

但是，也许是因为它孵化得早，布谷鸟小鸡没能记住密码，所以它没有发出正确的乞求叫声。