密歇根新闻广播 气候变化 连鸟儿都不得不出来赶个早春

New research shows that in order for some early birds to catch the worm, they have to breed sooner in the spring.

Luke DeGroote is the avian research coordinator¹ at Carnegie Museum of Natural History, and he runs the bird banding program at the museum's Powdermill Nature Reserve.

Right now, he's in the thick of spring migration².

"It's sort of a bit like fishing, in a way. We put out our nets to see what we catch," he says.

From early in the morning, until about noon, he and a handful of volunteers patrol a series of nets that look like volleyball nets that are set up around the property.

"This is a red-winged blackbird. I'm going to grab him by the body, and very carefully pull the netting off the tip of the wing," he says.

Birds like this little guy, with the distinctive³ red patch on its wing, get caught up in the fine netting, and drop down into a pocket where they're scooped⁴ up by researchers.

DeGroote gingerly places the bird into a bag, like a small pillow case, and loops its string to a red carabiner around his neck. Red indicates which size metal band to place on the blackbird's leg, so it can be tracked.

All the birds they capture this morning, and every morning, are taken back to a small lab where they're banded with a unique number and weighed. Researchers also examine their feathers to determine age, and if the birds are getting ready to breed.

"The females will lose the feathers on the breast and then insert some fluid to create really like a hot water bottle for the eggs," says DeGroote.

Early birds

They've been collecting these data here at Powdermill, consistently, for over 50 years. That's how they know, from previous studies, that birds are migrating here a little earlier in the spring than they used to, and breeding sooner.

And that got DeGroote and his research partner Molly McDermott thinking:

"All right, if they're migrating early and breeding early, are they breeding earlier because they're migrating early or are they breeding more quickly after they arrive?" says DeGroote.

Their findings?

"They're basically getting busier earlier after arrival," he says.

That's true for the majority of the 17 common bird species they studied. In their recent paper, published in the journal PLOS One, they connect early breeding to warmer springs and climate change.

Because while birds are arriving here a day earlier for every one degree Celsius⁵ that the temperature has warmed over the last few decades, spring buds are opening three days earlier.

Those plants, and the insects birds rely on for food for the survival of their young, are now sort of mismatched with the timing⁶ of spring migration. So these birds are responding the only way they can.

"They're having to catch up because they're not able to catch up during migration; they're not able to sort of advance that as much as the plants. They have to begin breeding soon after arrival if they want to breed at a time period that's sort of what they're used to," says DeGroote.

In other words, when the tender plants and insects they eat are at their peak. A quarter of the species which bred earlier in this study, like black-capped chickadees, had more babies in these warmer years. But another 25%, including hooded⁷ warblers, didn't. Their productivity declined.

DeGroote says you can look at the results of this study two ways. On the glass-half-full side, it shows some bird species are flexible, and capable of adapting to climate change. But while weather isn't climate, a few years ago there was a hard winter and later spring, and this year is warmer, he says the overall trend for birds is worrying.

"If it continues to warm, that window which they have to be adaptable⁸ is shrinking," says DeGroote.

This most recent study just looks at the timing of bird breeding, but DeGroote says it's easy to see implications for the ecosystem⁹. If some species are less successful because of climate change, there might be fewer birds to pick off insects or spread seeds from the fruits they eat.

1 coordinator   

n.协调人

参考例句：

• The UN Office for the Coordination of Humanitarian Affairs, headed by the Emergency Relief Coordinator, coordinates all UN emergency relief. 联合国人道主义事务协调厅在紧急救济协调员领导下，负责协调联合国的所有紧急救济工作。
• How am I supposed to find the client-relations coordinator? 我怎么才能找到客户关系协调员的办公室？

2 migration   

n.迁移，移居，（鸟类等的）迁徙

参考例句：

• Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
• He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。

3 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。

4 scooped   

v.抢先报道( scoop的过去式和过去分词 )；（敏捷地）抱起；抢先获得；用铲[勺]等挖（洞等）

参考例句：

• They scooped the other newspapers by revealing the matter. 他们抢先报道了这件事。 来自《简明英汉词典》
• The wheels scooped up stones which hammered ominously under the car. 车轮搅起的石块，在车身下发出不吉祥的锤击声。 来自《简明英汉词典》

5 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

6 timing   

n.时间安排，时间选择

参考例句：

• The timing of the meeting is not convenient.会议的时间安排不合适。
• The timing of our statement is very opportune.我们发表声明选择的时机很恰当。

7 hooded   

adj.戴头巾的；有罩盖的；颈部因肋骨运动而膨胀的

参考例句：

• A hooded figure waited in the doorway. 一个戴兜帽的人在门口等候。
• Black-eyed gipsy girls, hooded in showy handkerchiefs, sallied forth to tell fortunes. 黑眼睛的吉卜赛姑娘，用华丽的手巾包着头，突然地闯了进来替人算命。 来自辞典例句

8 adaptable   

adj.能适应的，适应性强的，可改编的

参考例句：

• He is an adaptable man and will soon learn the new work.他是个适应性很强的人，很快就将学会这种工作。
• The soil is adaptable to the growth of peanuts.这土壤适宜于花生的生长。

9 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。