Thorough investigations resulted in 29, 34 and 45 bp in 1998-2000, respectively. The majority of the population is located in open agricultural areas in Groningen and Flevoland, with additional pairs in marshes in Lauwersmeer. The breeding distribution since the mid-1970s has shifted towards the northeast, as Zuidelijk Flevoland (newly reclaimed in 1968, five years before the first atlas started) became cultivated and breeding on the Wadden Sea islands or in the south and east of the country has vanished. The current population highly depends upon nest protection and the conservation of large-scale agricultural landscapes. Food shortage may well be a future problem.
- 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.