In 1998-2000 around 14,500 bp were counted, mainly concentrated in one colony in the Wadden Sea (Griend, max. 7920) and two in the Delta area (Hompelvoet and Hooge Platen, 4100 and 3500, respectively). Settlements elsewhere are erratic and often not successful. Breeding numbers dropped in the 1960s because of pesticides, with only 875 bp remaining in 1965. Although numbers have slowly recovered since, population levels of the 1950s (27,000-35,000 bp) have never been regained.
- 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.