英语语法分析

They're pretty close to the ground, but these warblers also nest in forests that have low shrub density.

它们离地面很近，但是这些蓝莺也会在灌木密度低的森林里面筑巢。

The confirmation researchers had been seeking was finally achieved in studies involving two varieties of warblers.

在对两种莺的研究中，研究人员一直在寻找的证据最终得到了证实。

The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives.

相比在树上筑巢的同种类雏鸟，在地面筑巢的鸣禽雏鸟会发出频率更高的乞食叫声。