Distribution and, particularly, numbers may have been slightly underestimated due to inconspicuous behaviour of the species. It is distributed over most of the higher grounds, with a patchy occurrence elsewhere. Higher densities (more than 10 bp/square) are recorded in old deciduous forests, estates and former willow-thickets. A marked range expansion since the 1970s is related to more natural forest management and maturation of woodland. Locally, declining numbers are also recorded, e.g. in south Limburg and parts of the river district. The population is estimated at 4500-5500 bp in 1998-2000.