Birds called oxpeckers gobble ticks off the skin of rhinos and zebras.

牛椋鸟这种鸟类食用犀牛和斑马皮肤里的虱子。

But when oxpeckers were present, the birds alerted the rhinos 100 percent of the time.

但牛椋鸟在场时，其会100%提醒黑犀牛。

The study is in the journal Current Biology, with oxpecker recording by Tiffany Plantan of the University of Miami.

这项研究发表在《当代生物学》期刊上，牛椋鸟的叫声录音由迈阿密大学的蒂芙尼·普兰坦录制。

Plotz thinks the oxpeckers may have evolved their sentinel behavior because it protects their convenient food source.

普洛茨认为，牛椋鸟可能为了保护方便的食物来源，而进化出哨兵行为。

But the rhinos may have an unlikely ally against poachers: the red-billed oxpecker.

但在对抗偷猎者方面，黑犀牛有个看似不太可能的盟友：红嘴牛椋鸟。

And the more oxpeckers on the scene, the greater the detection distance-which means the earlier the warning.

出现的牛椋鸟越多，探测距离就越远，这意味着发出警报的时间也越早。

To test whether the oxpeckers do, in fact, act as noisy lookouts, Plotz and his team implanted radio transmitters in the rhinos' horns.

为了测试牛椋鸟是否确实能成为聒噪的守望者，普洛茨及其团队在黑犀牛角里植入了无线电发射器。

The researchers found that rhinos without oxpeckers detected an approaching human only 23 percent of the time, at an average distance of 27 meters.

研究人员发现，背上没有牛椋鸟的黑犀牛发现人类接近的概率仅有23%，平均距离27米。