气候的“多米诺骨牌效应”影响到候鸟生存

图解：迟到了. 由于气候变化，花斑鹟不能及时到达为其后代捕捉食物。

人类：俗语说，早起的鸟儿能捉到虫子（Early bird can catch worms ），你们干吗不早到呢？
候鸟：都是由于气候变化的缘故。

气候变化改变了食物供应，威胁到生存。

花斑鹟（pied flycatchers,），是略小于麻雀的普通候鸟，以昆虫为食的欧亚大陆鹟科鸟类，通常捕捉飞虫。但是，由于气候变化，它们正面临春天缺食而行将死亡的危险，这是本周一组科学家的研究报告。本发现表明了季节变化的复杂的多米诺骨牌效应。季节变化影响到食肉动物、捕食动物。

此种候鸟每年春天从非洲的寒冷地带飞行数千公里到欧洲觅食繁衍。 2001年,科学家与荷兰生态研究所发现鹟鸟因抵达欧洲的时间太晚而没有太多的时间繁殖。现在,赫罗纳大学（University of Groningen）进化生态学者Christiaan Both同来自该研究所的科学家合作，通过称量昆虫的粪便来衡量有多少可供鹟鸟可吃的毛毛虫。……


对于气候的变化如何改变生态互动的时间进程,科学家的了解还在初始阶段。很多人猜想跨物种的影响将会是很大的。

编译自Science Now,Friday, 5 May 2006 


Migrating Birds Not Early Enough

Climate change has shifted food supplies, threatening survival


Some pied flycatchers, a common migratory bird slightly smaller than a sparrow, are missing their spring meals and dying as a result of climate change, a team of scientists reported this week. The discovery is one of the most sophisticated showing the domino effect of shifting seasons and their impact on predators and prey.


The migratory birds fly thousands of kilometers each spring from wintering grounds in Africa to Europe, where they breed. In 2001, scientists with the Netherlands Institute of Ecology found that the flycatchers‘ reproduction suffered because they arrived in Europe too late to have much time to breed. Now, University of Groningen evolutionary ecologist Christiaan Both worked with scientists from the institute and measured how many caterpillars were available for the birds to eat by weighing the insects‘ droppings. Caterpillars, they learned, have responded to an earlier spring by moving up their peak emergence by 16 days.


But some of the birds are only breeding a week earlier than they used to--and their young are consequently missing out on many meals. "It‘s impossible for them to predict when the spring starts in Europe," says Both. That‘s had a profound impact, the team reported in the 4 May Nature. Among nine flycatcher populations they studied over 2 decades, the researchers found that those that mistimed their arrival declined in number by a stunning 90%, compared to better-synchronized groups that suffered only a 10% drop. Both hopes that genetics will help explain why some pied flycatchers are leaving Africa sooner. Both is also hoping to begin tracking birds to see if they are adapting by migrating to European areas further north.


"It‘s a really important piece of the puzzle," says Cornell University ornithologist David Winkler, who reviewed the paper for Nature. "He‘s adding detail to the avian response to climate change that we don‘t have elsewhere." Scientists are only beginning to learn how climate change alters the timing of ecological interactions, but many suspect the cross-species impacts are going to be great. Both‘s work, Winkler says, suggests that other studies may be missing the fact that even when the birds migrate sooner, they might still be missing food or other ecological needs.