(单词翻译:单击)
听力文本
This is Scientific American's 60-second Science, I'm Susanne Bard.
Black rhinos have terrible eyesight. Even so, these giant African herbivores easily fend off hungry lions and hyenas.
"Their basic body plan has proved to be good enough to survive on a savanna full of large predators, being very large, thick-skinned—big, rapierlike horns."
Victoria University of Melbourne behavioral ecologist Roan Plotz. But those protective traits are no match for humans with guns. Today the species is critically endangered largely due to poaching. But the rhinos may have an unlikely ally against poachers: the red-billed oxpecker. The chatty, sociable birds often hang out on the backs of rhinos, feasting on parasitic ticks.
"And actually, research has shown that the tick is the favorite diet of an oxpecker. And if they feed on ticks, that is a good thing."
The birds also get nutrients by picking at sores on the rhinos' bodies. Plotz suspected that the rhinos put up with this indignity because the oxpeckers make loud alarm calls whenever they see humans approach—giving the rhinos an early warning to flee.
"And it's sort of a distinctive rattling, a bit hissing sort of sound."
(CLIP: Alarm call)
To test whether the oxpeckers do, in fact, act as noisy lookouts, Plotz and his team implanted radio transmitters in the rhinos' horns. This didn't hurt the rhinos and allowed the researchers to track the animals...
"And approach them undetected, when the oxpeckers were on the back and when the oxpeckers were not on their backs, to get an idea of if the birds do alert them and if the rhinos do listen."
The researchers found that rhinos without oxpeckers detected an approaching human only 23 percent of the time, at an average distance of 27 meters. But when oxpeckers were present, the birds alerted the rhinos 100 percent of the time. And they detected the human 61 meters away on average. And the more oxpeckers on the scene, the greater the detection distance—which means the earlier the warning.
"Which makes sense because the more eyes you have on your back, looking out for you, the more chance that they can pick up anything coming. What we think is going on, fundamentally, is that the rhino is eavesdropping on the oxpecker alarm call, there can be no doubt of that. There's a really strong antihuman benefit to listening to oxpecker alarm calls."
The study is in the journal Current Biology, with oxpecker recording by Tiffany Plantan of the University of Miami.
Plotz thinks the oxpeckers may have evolved their sentinel behavior because it protects their convenient food source. And the more lookouts, the better in what seems like a win-win for both species: the birds thrive and the rhinos survive.
Thanks for listening for Scientific American's 60-second Science. I'm Susanne Bard.
参考译文
这里是科学美国人——60秒科学系列，我是苏珊娜·巴德。
黑犀牛的视力很差。即便如此，这些非洲大型食草动物也能轻松地抵抗饥饿的狮子和鬣狗。
“事实证明，它们的基本身体规划足够优秀，能在布满大型捕食者的非洲大草原上生存，使其成为体型庞大、皮糙肉厚、角似长剑的动物。”
墨尔本维多利亚大学的行为生态学家罗恩·普洛茨说到。但这些保护性特征无法抵抗持枪人类。现在，这个物种成为极度濒危物种的主要原因是偷猎。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。这种健谈、好交际的鸟经常在犀牛背上闲逛，尽情享用寄生扁虱。
“研究表明，扁虱是牛椋鸟最喜欢的食物。如果它们以扁虱为食，那是件好事。”
这些鸟还通过啄食黑犀牛身上的溃疡来获取营养。普洛茨怀疑，黑犀牛忍受这种侮辱的原因是，牛椋鸟看到人类靠近时会发出响亮的警报叫声，这给黑犀牛提供了逃跑预警。
“这是一种独特的卡嗒声，还夹带点嘶嘶声。”
（音频剪辑：警报叫声）
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。这不会伤害黑犀牛，而是为了让研究人员得以追踪这些动物……
“无论牛椋鸟是否在黑犀牛背上，我们都能在未被发现的情况下接近它们，以了解这种鸟是否能提醒黑犀牛，以及黑犀牛是否听到了警报。”
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。但牛椋鸟在场时，其会100%提醒黑犀牛。这些鸟在平均61米外就能探测到人类。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。
“这是有道理的，因为你背上盯梢的眼睛越多，发现物体接近的几率就越大。从根本上来说，我们认为黑犀牛在偷听牛椋鸟的警报叫声，这是毫无疑问的。听牛椋鸟的警报叫声，是严重反人类的利益。”
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。
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。哨兵越多越好，这对两个物种来说似乎是双赢局面：牛椋鸟繁衍生息，黑犀牛得以生存。
谢谢大家收听科学美国人——60秒科学。我是苏珊娜·巴德。
译文为可可英语翻译，未经授权请勿转载！
重点讲解
重点讲解：
1. fend off 挡住，抵挡(攻击)；
He raised his hand to fend off the blow.
他抬起手来抵挡那一拳。
2. no match for 不能与…相比；敌不过…；
I was no match for a man with such power.
我根本不是这样强大的男人的对手。
3. put up with 忍受；容忍；
They have to put up with a giant oil refinery right on their doorstep.
他们不得不忍受就在家门口的巨型炼油厂。
4. eavesdrop on 偷听；窃听；
Some journalists will always try to eavesdrop on the private conversations of the Royal family.
有些记者总想设法偷听皇室成员的私下交谈。
