All major colonies are located within 15-20 km of large water bodies and are situated in or near wetlands in the lower parts of the country. Marked range expansion since 1973-77 (only four occupied atlas squares, all around Lake IJsselmeer) was accompanied by a strong population increase from 3000 bp in 1977 to 20,000 in the early 1990s. Numbers in 1998-2000, after some decrease in the mid-1990s, remained stable at around 19,000 bp. The species has benefited from protection measures and eutrophication of surface waters in the 1980s, resulting in booming stocks of several fish species.
Eerden, M. van, Platteeuw, M., Rijn, S. van
- 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.