Shorebird populations, especially those feeding on shellfish, have strongly declined in recent decades and identifying the drivers of these declines is important for conservation. Changing food stocks are thought to be a key driver of these declines and may also explain why trends have not been uniform across Europe's largest estuary. We therefore investigated how winter population trends of Eurasian oystercatchers (Haematopus ostralegus) were linked to food availability in the Dutch Wadden Sea. Our analysis incorporated two spatial scales, a smaller scale focused on roost counting areas and food available to birds in these areas and a larger spatial scale of tidal basins. A novelty in our study is that we quantify the connectivity between roosting and foraging areas, identified from GPS tracking data. This allowed us to estimate food available to roosting birds and thus how food availability may explain local population trends. At the smaller spatial scale of roost counting areas, there was no clear relationship between available food and the number of roosting oystercatchers, indicating that other factors may drive population fluctuations at finer spatial scales. At the scale of tidal basins, however, there was a significant relationship between population trends and available food, especially cockle Cerastoderma edule,. Mortality and recruitment alone could not account for the large fluctuations in bird counts, suggesting that the site choice of wintering migratory oystercatchers may primarily drive these large fluctuations. Furthermore, the relationship between oystercatcher abundance and benthic food stocks, suggests winter shorebird counts could act as ecological indicators of ecosystem health, informing about the winter status of food stocks at a spatial scale of tidal basins.

近几十年来，水鸟种群，尤其是那些以贝类为食的水鸟数量急剧下降，确定这些减少的驱动因素对保护很重要。不断变化的食品库存被认为是这些下降的关键驱动因素，也可以解释为什么整个欧洲最大的河口的趋势不一致。因此，我们调查了欧亚牡蛎（Haematopus ostralegus）的冬季种群趋势如何) 与荷兰瓦登海的食物供应有关。我们的分析包含两个空间尺度，一个较小的尺度侧重于栖息地计数区域和这些区域鸟类可用的食物，以及潮汐盆地的较大空间尺度。我们研究的一个新颖之处在于我们量化了栖息和觅食区域之间的连通性，从 GPS 跟踪数据中确定。这使我们能够估计栖息鸟类可用的食物，从而估计食物供应如何解释当地人口趋势。在较小的栖息计数区空间尺度上，可用食物与栖息牡蛎数量之间没有明显的关系，表明其他因素可能会在更精细的空间尺度上驱动种群波动。然而，在潮汐盆地的规模上，Cerastoderma edule ,. 仅靠死亡率和补充不能解释鸟类数量的大波动，这表明越冬洄游牡蛎捕捞者的地点选择可能主要推动这些大波动。此外，牡蛎丰度与底栖食物储备之间的关系表明，冬季滨鸟数量可以作为生态系统健康的生态指标，在潮汐盆地的空间尺度上告知食物储备的冬季状况。