Connectivity of wetland areas along the East Atlantic Flyway used as moulting and stopover sites by Pied Avocets (Recurvirostra avosetta) during autumn migration

Abstract Stopovers during migration periods are essential to allow birds to accumulate energy, recover, and/or avoid adverse weather conditions. Recoveries of ringed birds have shown that Pied Avocets ( Recurvirostra avosetta ) may winter at various places along the East Atlantic Flyway (EAF); however, the connectivity of different stopover sites remains poorly understood. The present study aimed to investigate the spatial and temporal stopover patterns of Pied Avocets and clarify how different wetland areas along the EAF are connected for staging Avocets. We caught 19 adult Avocets at their breeding colonies in the German Wadden Sea using walk-in-traps and tagged them with GPS data loggers (weight 9 g). The Wadden Sea areas of Schleswig-Holstein, Lower Saxony, and the Netherlands were frequently used as stopover sites. Most stopover sites were located at coastal wetlands, with only a few at inland wetlands. On average, the tagged Pied Avocets made 9.1 ± 5.1 stopovers during autumn migration and spent a total of 123.0 ± 45.2 days at stopover sites, with an average stopover duration of 13.4 ± 23.8 days per stopover. Pied Avocets spend more time at stopover sites during migration than many other waders, highlighting the critical importance of high-quality stopover sites for their annual cycle. Muddy estuarine areas in the Wadden Sea (Elbe, Jade-Weser, Ems-Dollart) play an important role during the early migration stages, and should thus be a specific focus for future monitoring actions.