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。
The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives.
很多种鸟常常混群共同迁徙，但是当他们停下来觅食休息的时候，你就会发现不同的种类有的在地面上，有的在中层高度，有的则在树顶处。
Mixed flocks of several species often travel together, but when they are feeding or resting you will spot different birds on the ground, at mid-level heights and at the tree tops.
而地面上检出的细菌种类最多，正像作者所称是“形形色色的细菌群落”，包括几种通常存在于土壤中的细菌。
The floor had the biggest bacteria party, revealing what the authors called "diverse bacterial communities" of organisms, including several typically found in soil.
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