Cuckoos and sparrow hawks have almost identical patterns on their underbellies.

阅读难度：

Cuckoos have evolved plumage patterns that give them a hawk-like appearance to scare the birds whose nests they invade, say scientists, the BBC reports.

A study has shown that reed warblers -- a cuckoo host species -- are less likely to attack more "hawk-like" cuckoos.

As brood parasites, cuckoos first need to lay an egg without being "mobbed" or attacked by the nest's owner.

Dr Justin Welbergen from the University of Cambridge, UK, who led this research, said "The most striking similarity between a cuckoo and a sparrow hawk is the bar patterns on both species' underbellies."

So his team covered the barred bellies of the cuckoo and sparrow hawk models with white cloth, to study the reed warblers' reactions to both the covered and uncovered models.

"We found that the reed warblers were more reluctant to approach the birds if the dummies had barring on their chests," Dr. Welbergen said.

（点击英国广播公司网站查看原文）

杜鹃身着鹰袍

       据英国广播公司报道，科学家称，进化使得杜鹃身上的羽毛图案和鹰极为相似，以此来吓唬寄主，择巢产卵。

       研究显示，杜鹃经常把卵生在苇莺巢内，而苇莺并不敢轻易攻击长相似鹰的杜鹃。

       作为孵卵寄生鸟类，杜鹃得在不受攻击或“群殴”的情况下顺利把卵生在寄主巢内。

       主持这项研究的英国剑桥大学贾斯汀•韦伯尔根博士表示，杜鹃和雀鹰胸前的条纹极为相像。

       据此，他的团队制作了杜鹃和雀鹰标本，用白布遮住前胸，以观察苇莺对待二者有何不同。

       他们最终发现面对那些装饰了条纹的鸟类标本，苇莺接触起来更为谨慎。

(China.org.cn April 19, 2011)