Wetenschappelijk artikelKentish Plovers of the southern North Sea congregate at a few important moulting sites after the breeding season

Moult is a crucial stage in the annual cycle of birds, consuming a lot of energy and increasing the risk of predation, thus requiring undisturbed environments. In this study, we investigated gatherings of Kentish Plovers Anarhynchus alexandrinus at moulting sites at the southern North Sea, focusing on identifying key moulting sites and understanding site connectivity. We conducted a trilateral, synchronous count in August 2023, covering the Wadden Sea of Denmark, Germany and the Netherlands as well as the Dutch Delta area, and compared the results with data from previous years. We identified three major moult sites: the island of Fanø (Denmark), the sandbars off St. Peter-Ording (Germany), and the Verklikkerstrand in the Dutch Delta area, which collectively held 86% of the observed Kentish Plovers. Through resightings of colour-ringed individuals, we revealed strong connectivity between breeding and moulting sites, particularly between the Beltringharder Koog nature reserve and the sandbars off St. Peter-Ording. Furthermore, we observed some individuals traveling longer distances to reach remote moulting sites. This was the case for two colour-ringed individuals from Marker Wadden in the Netherlands that – after the breeding season – travelled almost 300 km north-east to the sandbars off St. Peter-Ording. Additionally, we documented human disturbance, especially from recreational activities, impacting the moulting birds and potentially increasing their energy expenditure and predation risk. Our findings underscore the importance of protecting key moulting sites to support population viability. We recommend establishing temporary protection zones during the moulting season to reduce disturbances. We plan to conduct future synchronous counts to further investigate potential variation in the birds’ use of the identified moulting sites, and to implement these results in conservation measures for this declining population.