The breeding distribution is slightly influenced by non-breeding birds, that are sometimes hard to distinguish from breeders. Core areas with some tens of bp/square were only recorded in peat moors and fens on the sandy soils. Since the 1970s the species has withdrawn from peripheral sites. Population levels in 1995-96, just before the atlas period, were perhaps the lowest since 1970; this partly reflects the impact of two severe winters and low water tables in spring. Numbers in 1998-2000 (2000-2500 bp) were rather low, compared to the 1970s and early 1980s (2300-5000).
Dijk, A. J. van