人们发现，录音机在播放树上筑巢的鸣禽的乞食叫声时，比起在播放地面筑巢的鸣禽的乞食叫声时，鸟蛋被攻击的几率明显增大。
The eggs "advertised" by the tree-nesters' begging calls were found bitten significantly more often than the eggs associated with the ground-nesters' calls.
这是地面指挥中心呼叫航天飞机“发现号”。
This is Mission Control calling the space shuttle Discovery.
一旦发现任何危险，雄性就用鼻子轻拍地面。
As soon as he detects any danger, the bull taps on the ground with his trunk.
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