英语听力：自然百科 大堡礁 自然奇迹(27)（在线收听）

A pair of noddy terns fly close together over the island on the reef.

一对白顶玄燕鸥在礁石岛上空比翼而飞。

They are two mates, reaffirming their bond.

它们是在重复确认伴侣关系。

Noddies signal to each other continually during courtship,both in the air and after landing.

求偶期的白顶玄燕鸥会不停地表演，无论是在空中还是地上。

Once in the trees,the performance changes.

到了树上的燕鸥的表演方式也随之改变。

They bow their heads repeatedly.

它们不停地相互点头。

It's pretty clear how they got their name.

这也是人们又叫它点头燕鸥的原因。

To enforce their relationship,the male has to collect nesting materials,and the females are famously fussy,so he chooses his present carefully.

求偶关系成功后，关系还需要经营。雄燕鸥的任务是收集筑窝的材料。而雌燕鸥在这方面极为挑剔，礼物得精挑细选。