Sonja Weeda, Maarten Hotting, René Vos, Camilla Dreef, Yvonne Verkuil & Jan van der Winden (2025) Marker Wadden helps Kentish Plovers Anarynchus alexandrinus to breed successfully in a freshwater habitat. LIMOSA 98 (1): 17-27.

Kentish Plovers breed on bare to sparsely vegetated, open, often shell-rich areas, usually in the vicinity of saline or brackish water. The Dutch breeding population has decreased significantly and the Kentish Plover is now endangered in the Netherlands. Most of the population breeds in coastal habitats in the Southwestern Delta and a smaller part in the Dutch Wadden Sea area. Between the 1940s and 1995 breeding Kentish Plovers were more numerous in freshwater areas, available because of the closure of the Zuiderzee, the Lauwerszee and the sea inlets in the Delta, the construction of the polders in lake IJsselmeer and the urban development of Amsterdam. In 2017 Marker Wadden was constructed in the freshwater lake Markermeer. By 2021 a 1000 ha archipelago with shallow waters, silt compartments with sparsely vegetated/bare mudflats and areas covered with Marsh Fleawort Tephroseris palustris and low vegetation and sandy beaches and artificial dunes. The construction took several years and therefore new pioneer biotope was present every year. Kentish Plovers settled immediately at Marker Wadden. We counted the breeding population in 2017 and from 2019 till 2021 we monitored the breeding success. During the study period, 6-9% of the national population bred on Marker Wadden, which made it an important Dutch breeding area, with a long period of settlements and resettlements of 15 weeks every year. Our study showed that Kentish plovers are well able to reproduce in freshwater environments. The breeding pairs of Marker Wadden have contributed approximately 10-20 chicks per year to the population of the Kentish Plover in the Netherlands in the years 2019-21. If we compare this with the breeding success in other areas, it appears that Marker Wadden is not only a good habitat for them, but the reproduction was higher in these years than in the Delta and the Dutch Wadden Sea. We think that the importance of Marker Wadden for Kentish Plovers is the consequence of an abundance of sandy habitat with mudflats that provides ample breeding and foraging habitat, while ground predators and recreation are absent. Naturally, the pioneer habitats on Marker Wadden will be temporary, because vegetation succession will make it less suitable for Kentish Plovers. However, partly due to the long construction period and locally slow vegetation development, the area has now been relevant for Kentish Plovers for seven years. The last islands were completed in 2022 and we expect that the area will remain important for a few more years. Because the numbers and reproduction are better than in most other areas, we recommend creating and optimally managing more new breeding biotopes in freshwater lakes far from the coast in the Netherlands. This can temporarily contribute positively to the Kentish Plover population.

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