Dipartimento di Biologia, Università di Milano, Milano, Italy.
Proc Biol Sci. 2011 Mar 22;278(1707):835-42. doi: 10.1098/rspb.2010.1778. Epub 2010 Sep 22.
Climate is changing at a fast pace, causing widespread, profound consequences for living organisms. Failure to adjust the timing of life-cycle events to climate may jeopardize populations by causing ecological mismatches to the life cycle of other species and abiotic factors. Population declines of some migratory birds breeding in Europe have been suggested to depend on their inability to adjust migration phenology so as to keep track of advancement of spring events at their breeding grounds. In fact, several migrants have advanced their spring arrival date, but whether such advancement has been sufficient to compensate for temporal shift in spring phenophases or, conversely, birds have become ecologically mismatched, is still an unanswered question, with very few exceptions. We used a novel approach based on accumulated winter and spring temperatures (degree-days) as a proxy for timing of spring biological events to test if the progress of spring at arrival to the breeding areas by 117 European migratory bird species has changed over the past five decades. Migrants, and particularly those wintering in sub-Saharan Africa, now arrive at higher degree-days and may have therefore accumulated a 'thermal delay', thus possibly becoming increasingly mismatched to spring phenology. Species with greater 'thermal delay' have shown larger population decline, and this evidence was not confounded by concomitant ecological factors or by phylogenetic effects. These findings provide general support to the largely untested hypotheses that migratory birds are becoming ecologically mismatched and that failure to respond to climate change can have severe negative impacts on their populations. The novel approach we adopted can be extended to the analysis of ecological consequences of phenological response to climate change by other taxa.
气候变化的速度非常快，对生物产生了广泛而深远的影响。如果生物无法根据气候变化来调整生命周期事件的时间安排，就可能导致生物与其他物种的生命周期以及非生物因素之间的生态不匹配，从而危及种群的生存。有研究表明，一些在欧洲繁殖的候鸟数量的减少，可能是由于它们无法调整迁徙的物候期，以适应繁殖地春季事件的提前。事实上，有几种候鸟已经提前了它们的春季到达日期，但这种提前是否足以补偿春季物候期的时间变化，或者鸟类是否已经变得生态上不匹配，仍然是一个尚未解决的问题，只有极少数例外。我们使用了一种新的方法，该方法基于积累的冬季和春季温度（度日）作为春季生物事件时间的代理，来测试 117 种欧洲候鸟在过去五十年中到达繁殖地的春季时间是否发生了变化。候鸟，特别是那些在撒哈拉以南非洲越冬的候鸟，现在到达时的度日值更高，因此可能积累了“热滞后”，从而可能与春季物候期的匹配度越来越低。具有较大“热滞后”的物种表现出更大的种群下降，而这种证据并没有受到伴随的生态因素或系统发育效应的混淆。这些发现为一个尚未得到充分验证的假说提供了普遍支持，即候鸟正在变得生态上不匹配，而无法对气候变化做出响应可能会对它们的种群产生严重的负面影响。我们采用的新方法可以扩展到对其他分类群对气候变化的物候响应的生态后果的分析。
