氣候變化導(dǎo)致美國鳥類體型減小

氣候變化導(dǎo)致美國鳥類體型減小

Birds are shrinking and their wingspans are growing as a result of global warming.

由于全球變暖，鳥類體型在萎縮，翅膀在增長。

That’s the shocking conclusion made by scientists who measured tens of thousands of birds collected over 40 years in the US.

這是科學(xué)家們得出的令人震驚的結(jié)論，他們對美國40多年來收集的數(shù)萬只鳥類進行了測量。

The animals were collected and analyzed after they had died following collisions with buildings in Chicago, Illinois.

這些動物在伊利諾伊州芝加哥市與建筑物相撞后死亡，隨后被收集和分析。

A study published Wednesday involved 70,716 birds killed from 1978 through 2016 in such collisions.

周三公布的一項研究，涉及1978年至2016年間在此類碰撞中死亡的70716只鳥。

Scientists found that their average body sizes steadily dropped over that time, though their wingspans grew.

科學(xué)家發(fā)現(xiàn)，在這段時間里，它們的平均體型穩(wěn)步下降，盡管它們的翅膀有所增長。

The results suggest that a warming climate is driving down the size of some bird species in North America and perhaps around the world, the researchers said.

研究人員說，研究結(jié)果表明，氣候變暖正在使北美甚至全世界一些鳥類的體型縮小。

“We found almost all of the species were getting smaller,” Dr. Brian Weeks, an expert at the University of Michigan, told the BBC.

“我們發(fā)現(xiàn)幾乎所有的物種都在變小。”密歇根大學(xué)的專家布萊恩·威克斯博士告訴英國廣播公司。

“The species were pretty diverse, but responding in a similar way,” he said. “The consistency was shocking.”

“這些物種非常多樣化，但以相似的方式做出反應(yīng)，”他說。“這種一致性令人震驚。”

It’s not entirely clear why exactly the birds are shrinking, although scientists cited a phenomenon known as Bergmann’s rule as one possible reason.

目前還不完全清楚這些鳥為什么會萎縮，盡管科學(xué)家們將一種被稱為伯格曼法則的現(xiàn)象作為可能的原因之一。

Bergmann’s rule states that individuals within a species tend to be smaller in warmer regions and larger in colder regions.

伯格曼法則指出，一個物種內(nèi)的個體在溫暖地區(qū)往往較小，在寒冷地區(qū)則更大。

The study focused on 52 species — mostly songbirds dominated by various sparrows, warblers, and thrushes.

這項研究集中在52種鳥類身上，其中大部分是鳴禽，以各種麻雀、鶯和畫眉鳥為主。

Many breed in cold regions of North America and spend their winters in locations south of Chicago.

許多在北美寒冷地區(qū)繁殖，在芝加哥以南的地方過冬。

Over the four decades, body size decreased in all 52 species.

在過去的40年里，所有52個物種的體型都有所下降。