VAN ELS P, VAN WINDEN E, KLAASSEN O, SOLDAAT L & VAN TURNHOUT C (2020) A decade of national roost counts in the Netherlands. LIMOSA 93 (2): 92-102.

We provide an overview of communal roosts in the Netherlands. Within the European Bird Directive, specific goals are set regarding the number of roosting birds to safeguard communal roosts in protected areas and populations in surrounding areas that depend on these roosts. In the Netherlands, 135 bird species are known to roost communally. We report results of a decade of roost counts within the framework of the National Communal Roost Census for 17 well-counted species. Key sites for large numbers of communally roosting birds include the IJsselmeer for terns and waders, the Frisian lake district for waders and geese, Lake Lauwersmeer for terns, waders and geese, the riverine belt (central Netherlands) for geese, and the southeastern peatlands for Eurasian Crane Grus grus. For some species, numbers counted at roosts may be higher (up to 30% for Great Egret Ardea alba) than those reported by diurnal waterbird counts, indicating that roost counts provide a reliable additional methode for monitoring populations, especially for those species that forage in landscapes that are difficult to access.

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