Hibernating bats in the Netherlands in 1986-2020, based on the National Monitoring Scheme of Bat Hibernacula

摘要

Bats have been studied in their underground winter quarters in the Netherlands (and Flanders) since the 1930s. Over time, the focus has shifted from ecological and physiological research to monitoring. In the Netherlands these counts have been done aspart of the National Monitoring Scheme of bat hibernacula (NEM Meetprogramma Wintertellingen Vleermuizen) since 1986. Statistics Netherlands: (CBS) annually calculates national (winter) trends for seven bat species that hibernate in ‘traditional’ winter quarters. The importance of these counts has increased over the years: not only because of the length of the year-to-year counts but also because the data play an important role in nature policy, including providing data for the EU’s Habitat Directive reports. Almost all the bat species monitored in this national programme show a significant ‘strong or moderate increase’ with the number of counted bats generally increasing since 1986. However, there is always doubt about to what extent more and better counting or an actual increase in population drives these positive trends. Unfortunately, there is a lack of research looking into the population-ecological mechanisms underlying these trends. Nowadays some national trends are possibly stabilizing.It remains to be seen how the trends will develop in the coming years.