Breeding colonies, confined to the Wadden Sea islands, a narrow strip along the coast of Noord-Holland and the Delta area, occur generally in association with dunes, saltmarshes and harbours. Scattered but tiny settlements further inland, sometimes known for decades, are partly located in odd habitats, e.g. arable land in the Noordoostpolder (reclaimed polder in Lake IJsselmeer). The breeding population peaked in the 1980s (11,000 bp in 1985) but declined since. Colonies in the coastal dunes of the mainland became nearly abandoned as a result of predation by red foxes, which also forced the remaining pairs to breed on flat roofs in built-up areas. Population comprised 5600-6500 bp in 1998-2000.
- SOVON Vogelonderzoek Nederland 2002. Atlas van de Nederlandse broedvogels 1998-2000. Nederlandse Fauna 5: 1-584. Nationaal Natuurhistorisch Museum Naturalis, KNNV Uitgeverij & European Invertebrate Survey-Nederland, Leiden.