气候变化导致美国鸟类体型减小

气候变化导致美国鸟类体型减小

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

由于全球变暖，鸟类体型在萎缩，翅膀在增长。

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

这是科学家们得出的令人震惊的结论，他们对美国40多年来收集的数万只鸟类进行了测量。

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

这些动物在伊利诺伊州芝加哥市与建筑物相撞后死亡，随后被收集和分析。

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

周三公布的一项研究，涉及1978年至2016年间在此类碰撞中死亡的70716只鸟。

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

科学家发现，在这段时间里，它们的平均体型稳步下降，尽管它们的翅膀有所增长。

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.

研究人员说，研究结果表明，气候变暖正在使北美甚至全世界一些鸟类的体型缩小。

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

“我们发现几乎所有的物种都在变小。”密歇根大学的专家布莱恩·威克斯博士告诉英国广播公司。

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

“这些物种非常多样化，但以相似的方式做出反应，”他说。“这种一致性令人震惊。”

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.

目前还不完全清楚这些鸟为什么会萎缩，尽管科学家们将一种被称为伯格曼法则的现象作为可能的原因之一。

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

伯格曼法则指出，一个物种内的个体在温暖地区往往较小，在寒冷地区则更大。

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

这项研究集中在52种鸟类身上，其中大部分是鸣禽，以各种麻雀、莺和画眉鸟为主。

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

许多在北美寒冷地区繁殖，在芝加哥以南的地方过冬。

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

在过去的40年里，所有52个物种的体型都有所下降。