Black rhinos have terrible eyesight. Even so, these giant African herbivores(食草動物) easily fend off hungry lions and hyenas(土狼). 「Their basic body plan has proved to be good enough to survive on a savanna(熱帶草原) full of large predators(食肉動物), being very large, thick skinned, big rapier-like horns(角).」
黑犀牛的視力很差。儘管如此，這些巨大的非洲食草動物很容易就能抵禦飢餓的獅子和鬣狗。「事實證明，它們的基本體型足以在充滿大型食肉動物的熱帶草原上生存，這些動物體型很大，皮膚很厚，長著大而鋒利的角。」
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(偷獵). But the rhinos may have an unlikely ally against poachers: the red-billed oxpecker(啄木鳥). The chatty, sociable birds often hang out on the backs of rhinos, feasting on parasitic(寄生蟲) ticks(扁蝨).
墨爾本維多利亞大學行為生態學家普羅茨說。但是這些保護性的特徵並不能與人類的槍枝相匹敵。如今，由於偷獵，該物種已瀕臨滅絕。但是，在對付偷獵者時，犀牛會有一個本不太可能的盟友:紅嘴牛椋鳥。這種愛說話、好交際的鳥經常掛在犀牛背上，以寄生的蜱蟲為食。
「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(營養素) by picking at sores on the rhinos』 bodies. Plotz suspected that the rhinos put up with this indignity(輕蔑) because the oxpeckers make loud alarm calls whenever they see humans approach—giving the rhinos an early warning to flee.
事實上，研究表明蜱蟲是牛椋鳥最喜歡的食物。如果它們以蜱蟲為食，那是件好事。「鳥類還通過啃食犀牛身上的瘡來獲取營養。普羅茨懷疑，犀牛之所以能忍受這種侮辱，是因為無論何時，只要看到人類靠近，它們都會發出響亮的警報，給犀牛發出逃跑預警。
「And it's sort of a distinctive rattling(咯咯聲), a bit hissing(嘶嘶聲) sort of sound.」 (alarm call clip)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…
「這是一種獨特的格格聲，有點嘶嘶聲。為了測試這些牛椋鳥是否真的充當了嘈雜的瞭望臺，普羅茨和他的團隊在犀牛角中植入了無線電發射器。這並沒有傷害到犀牛，也讓研究人員得以追蹤這些動物……
「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.」
「當牛椋鳥在犀牛背後時，在沒有被發現的情況下接近它們，來了解鳥類是否會提醒犀牛，而犀牛是否會傾聽。」
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.
研究人員發現，沒有「牛椋鳥」的犀牛在平均27米的距離上發現人類接近的機率只有23%。但是當牛椋鳥出現時，這些鳥百分之百地提醒犀牛。它們在平均61米遠的地方發現了人類。而且，現場的牛椋鳥越多，探測距離越遠——這意味著預警越早。
「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(根本上), is that the rhino is eavesdropping(竊取) on the oxpecker alarm call, there can be no doubt of that. There's a really strong anti-human benefit to listening to oxpecker alarm calls.」
「這是有道理的，因為背犀牛的背上上有越多的眼睛在盯著，就越有可能發現任何東西。」我們認為根本的原因是，犀牛在偷聽牛椋鳥的報警電話，這是毫無疑問的。聽牛椋鳥的叫聲確實有很強的反人類益處。」
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(警戒行為) because it protects their convenient(方便的) 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.
這項研究發表在《當代生物學》雜誌上，還有邁阿密大學的Tiffany Plantan錄製的牛椋鳥的叫聲。普羅茨認為，牛椋鳥之所以進化出這種定點行為，可能是因為這種行為保護了它們便利的食物來源。瞭望臺越多越好，這對兩個物種來說似乎是雙贏——鳥類繁榮，犀牛存活。