Migratory waterbirds are experiencing severe declines worldwide due to habitat loss. Their life cycles often span different countries and continents, highlighting the need for safeguarding wetland networks along migratory flyways. However, there are gaps in understanding how changes in specific sites can impact species at the biogeographical scale. Here we used a wetland of international importance (the Guadalquivir marshes, SW Spain) as a case study to investigate the causes and consequences at the flyway scale of annual changes in wintering waterbird assemblages. To do so, we combined 38 years of local and international waterfowl winter counts, environmental and remote sensing data encompassing 432 Ramsar sites, and a functional approach through structural equation modelling (SEM). We show that the environmental conditions experienced by wintering waterfowl in the study area were correlated with changes in their biogeographical populations in the East Atlantic Flyway. We found that during the last 40 years, the waterfowl assemblage wintering at the Guadalquivir marshes has shifted from a community composed mainly by herbivores and pre‐Saharan dabbling granivores, to the current one dominated by Trans‐Saharan dabbling granivores. Declines in 9/15 of the species studied were associated with the deterioration of the Doñana National Park natural marshes, whereas changes in the remnant six species responded mainly to global factors, such as the increase in winter temperatures in other areas of their distribution range. These results underscore the importance of considering global factors and flyway population data when interpreting regional trends of migratory animals. But also, that changes in specific wetlands can have measurable global impacts. Being that the long‐term persistence of migratory animals in a changing world entails the protection and integrity of migratory flyways beyond national borders.

中文翻译：

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当地尺度的栖息地变化对迁徙迁徙路线上的水禽种群有重大影响


由于栖息地的丧失，全球迁徙水鸟的数量正在急剧下降。它们的生命周期通常跨越不同的国家和大陆，这凸显了保护迁徙迁徙路线沿线湿地网络的必要性。然而，在理解特定地点的变化如何在生物地理尺度上影响物种方面存在差距。在这里，我们以一个具有国际重要性的湿地（西班牙西南的瓜达尔基维尔沼泽）作为案例研究，在迁徙路线尺度上调查越冬水鸟群落每年变化的原因和后果。为此，我们结合了 38 年的本地和国际水禽冬季计数、涵盖 432 个拉姆萨尔湿地的环境和遥感数据，以及通过结构方程建模 （SEM） 的函数方法。我们表明，研究区域越冬水禽所经历的环境条件与其在东大西洋迁徙路线中的生物地理种群变化相关。我们发现，在过去的 40 年里，在瓜达尔基维尔沼泽地越冬的水禽群落已经从一个主要由食草动物和前撒哈拉涉猎食粮动物组成的群落转变为目前由跨撒哈拉涉猎食粮动物主导的群落。所研究物种中 9/15 的减少与多纳纳国家公园天然沼泽的恶化有关，而残余的 6 个物种的变化主要对全球因素做出反应，例如其分布范围其他区域的冬季温度升高。这些结果强调了在解释迁徙动物的区域趋势时考虑全球因素和迁徙路线种群数据的重要性。而且，特定湿地的变化可能会产生可衡量的全球影响。 由于迁徙动物在不断变化的世界中长期存在，因此需要对跨国界的迁徙迁徙路线进行保护和完整性。