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小头鸟儿难自救 气候变化正以多种不同的方式影响着地球上的动物，但科学家注意到了一个存在于多个物种的普遍趋势：它们都在变小，物理意义上的体型变小。但这是为什么？又意味着什么？ 从野生绵羊到林鼠，科学家已经在许多不同的动物物种中观察到了这一现象，但北美鸣禽的相关记录尤为充分。 美国密歇根大学（University of Michigan）的研究人员在2019年发表了一份数据集，记录了在美国芝加哥死于撞击窗户的7万多只鸟儿，数据显示，过去40年中有几十种鸟类的体型正在缩小。 美国圣路易斯华盛顿大学（Washington University in St. Louis）的研究生贾斯汀·鲍德温（Justin Baldwin）仔细看过数据后，发现有些细节极为突出。 贾斯汀·鲍德温说：“很明显，有些鸟类体型缩小的幅度更大，而其他的缩小幅度则相对小得多。” 那么问题来了，为什么有些鸟类比其他鸟类缩水更快呢？ 鲍德温和同事觉得鸟类行为可能对此有所影响。 脑袋更大的鸟类往往更聪明，会根据所处的环境改变自己的行为，这说明它们或许能保护自己少受气温升高的影响，论文的共同作者、华盛顿大学生物助理教授卡洛斯·波特罗（Carlos Botero）解释道。 “通过调整自己的行为，也就是改变觅食的地方、时间、对象以及获得食物资源的方式，它们就能在面对气候变暖带来的种种变化时，尽量减少自身所受的负面影响。”波特罗说道。 例如，脑袋更大的鸟类可能会在天热时……[查看全文] Climate Change Is Shrinking Animals, Especially Bird-Brained Birds Climate change is affecting animals in a lot of different ways. But scientists have noticed a common trend across a variety of species: they’re getting smaller. As in—physically smaller in size. But why, and what could this mean? Scientists have observed this phenomenon in very different animal species from wild sheep to woodrats. But it’s especially well-documented in North American songbirds. In 2019, researchers at the University of Michigan published a dataset of more than 70,000 birds that died after hitting windows in Chicago. The data showed the body sizes for dozens of species had actually shrunk over the past 40 years. But when Justin Baldwin, a graduate student at Washington University in St. Louis, took a closer look at the data … something stood out. Justin Baldwin: There clearly seem to be some species that were shrinking a lot and other species that were shrinking much less. Farzan: The question was … why were some bird species shrinking faster than others? Baldwin and his colleagues had a feeling that bird behavior might be playing a role. In birds, species with bigger brains tend to be smarter and can change their behavior based on their environment. That means that they might be able to buffer themselves from increasing temperatures, says Carlos Botero, an assistant professor of biology at Washington University and the study’s co-author. Carlos Botero: By adjusting their behavior, by changing the places that they look for food, the times of the day in which they do that, the things that they eat, and the ways in which they access those food sources. All those are ways in which they could experience a little bit less of a negative selection from all this variety of changes that we're seeing through climate change. Farzan: A bigger-brained bird, for example, might adjust its behavior and stay...[full transcript] “ Baldwin, J., Garcia‐Porta, J. and Botero, C., 2022. Phenotypic responses to climate change are significantly dampened in big‐brained birds. Ecology Letters, 25(4), pp.939-947. doi: 10.1111/ele.13971 封面图来源：John Duncan on Unsplash |
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