But he studied other attributes of birds, too—like the rhythmic sounds some species made during courtship by fluttering, shaking or rattling their feathers together.

但他也研究了鸟类的其他属性—— 比如一些物种在求偶期间通过拍打、 摇动或嘎嘎作响它们的羽毛发出的有节奏的声音。

If you have a set of keys in your pocket, they could be " rattling" together, or a bunch of coins could " rattle" as they hit each other and made noise.

如果你口袋里有一套钥匙，它们可能会“嘎嘎作响”在一起，或者一堆硬币在相互撞击并发出噪音时可能会“嘎嘎作响”。