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Bats in hibernation quarters

After a long period of decline in bat numbers, some species are now showing an upturn.

Trend until 1990


In the mid-20th century many bats in the Netherlands were in decline and some species even went extinct. The decline was caused by disturbance to their hibernation quarters, and the use of agricultural pesticides in agriculture and of wood preservatives in church roofs. Also thought to be important are the reduction in wooded banks and the other changes in the farmed landscape.

Trend since 1990


Since 1998 all bat species have been included in a bat protection plan. The various measures that have been implemented to protect them include the renovation and restoration of their hibernation quarters and the banning of damaging wood preservatives. Although not all the recommendations in the protection plan have been implemented (Hollander, 1998), the decline in some bat species seems to have been halted. The mean index is rising and all the individual species investigated are increasing, including the natterer's bat (see graph).

Brandt's bat, the natterer's bat, Geoffroy's bat and the greater mouse-eared bat are on the Red List of mammals.

Technical note


The graph shows the Species Group Trend Index (SGTI) for the following species (for each species the benchmark year is 1990 (= 100) and the trend is in parentheses): whiskered bat + Brandt's bat (these cannot be distinguished in the field) (increase), natterer's bat (increase) brown long-eared bat (increase), Geoffroy's bat (increase), greater mouse-eared bat (suspected increase) and Daubenton's bat (increase). The index figures for the natterer's bat have been shown separately, as an example.

The figures are based on counts made in winter in cellars, quarries, forts and bunkers (Ecological Monitoring Network). Species that hibernate in cavity walls and tree hollows are not monitored.

References


  • Daemen, B.A.P.J., W.J.R. de Wijs, A. Kaper, M.M. Straver en A.J. van Strien (1998). Resultaten van vleermuistellingen in overwinteringsverblijven in de periode, 1986-1997. Kwartaalbericht Milieustatistieken, 98 (3): 39-45.
  • Hollander, H. (1998). Evaluatie Nota Vleermuisbescherming 1988. VZZ, Utrecht.
  • Limpens, H., K. Mostert en W. Bongers (1997). Atlas van de Nederlandse vleermuizen. KNNV uitgeverij. Utrecht.
  • Lina, P.H.C. en G. van Ommering (1994). Rode Lijst van bedreigde en kwetsbare zoogdieren in Nederland. Informatie en Kennis Centrum Natuurbeheer. Wageningen.
  • LNV (1988). Vleermuisbescherming, verleden, heden en toekomst. Directie Natuur, Milieu en Faunabeheer. Ministerie van Landbouw, Natuurbeheer en Visserij. Den Haag.

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This page was last changed on 13 April 2004  (version 01).