Eighty years of hibernation surveys: from banding to monitoring and protection

Forty years ago, a collective of authors described the population trends of a number of bat species in the Netherlands in a special issue of Lutra: ‘The Dutch bats: population trends in winter and summer roosts’ (Daan et al. 1980). The motivation for this special issue was the legal protection granted to bats in 1973 by the Natuurbeschermingswet (Nature Conservancy Act) combined with the more or less simultaneous decrease in government financing of bat research and consequently, available knowledge. There was a heightened awareness among those involved of the need for more cooperation and exchange of information. The ‘bat world‘ at the time consisted of staff members of two university research groups (Utrecht University en University of Amsterdam), two government organisations in the field of nature management (Rijksinstituut voor Natuurbeheer / Research Institute for Nature Management and Staatsbosbeheer / State Forestry Service) and two natural history museums (Rijksmuseum van Natuurlijke Historie, now Naturalis Biodiversity Center, in Leiden and the Maastricht Natural History Museum). Furthermore, two volunteer groups were involved: the mammal study group of the NJN, (A)CJN (youth organisations for nature study) and the ‘groevenlopers’ (‘quarry walkers’) of the Studiegroep Onderaardse Kalksteengroeven (study group for subterranean marl quarries), part of the Natuurhistorisch Genootschap (natural history society) in Limburg. Apart from these organisations, there were a number of people who were at the time or formerly interested in bats. Everyone included, the ‘batworld’ summed up to about 40 people. The responses to a survey carried out among them showed wide support for....