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

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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.

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杜鵑身著鷹袍

?????? 據(jù)英國(guó)廣播公司報(bào)道，科學(xué)家稱，進(jìn)化使得杜鵑身上的羽毛圖案和鷹極為相似，以此來(lái)嚇唬寄主，擇巢產(chǎn)卵。

?????? 研究顯示，杜鵑經(jīng)常把卵生在葦鶯巢內(nèi)，而葦鶯并不敢輕易攻擊長(zhǎng)相似鷹的杜鵑。

?????? 作為孵卵寄生鳥類，杜鵑得在不受攻擊或“群毆”的情況下順利把卵生在寄主巢內(nèi)。

?????? 主持這項(xiàng)研究的英國(guó)劍橋大學(xué)賈斯汀?韋伯爾根博士表示，杜鵑和雀鷹胸前的條紋極為相像。

?????? 據(jù)此，他的團(tuán)隊(duì)制作了杜鵑和雀鷹標(biāo)本，用白布遮住前胸，以觀察葦鶯對(duì)待二者有何不同。

?????? 他們最終發(fā)現(xiàn)面對(duì)那些裝飾了條紋的鳥類標(biāo)本，葦鶯接觸起來(lái)更為謹(jǐn)慎。

(China.org.cn April 19, 2011)