Bat numbers increased more than 40% between 1993 and 2011, according to a new report by the European Environment Agency (EEA) which considers the state of bat populations across a number of European countries. However, many bat species are still threatened with extinction.
During the second half of the 20th century, European bat populations had declined significantly due to the destruction of roosts, intentional killing, intensive agriculture and changes in land use, which ultimately caused the fragmentation and degradation of their habitats. Additionally, bats were indirectly poisoned by toxic chemicals used in the treatment of roof timbers.
At present, the EEA report on bats shows that the studied species appear to have increased by 43% at hibernation sites between 1993 and 2011, with a relatively stable trend since 2003.* The report states that the apparent population increase for many bat species may reflect the impact of national and European conservation legislation, such as species and site protection, targeted conservation measures and widespread awareness raising, particularly under the EUROBATS agreement.
While it is extremely encouraging to see this increase in bat populations, many bat species are still threatened. According to the IUCN European Red List, also used in the report, 26% of bat species are threatened with extinction in Europe. Nature conservation is an ongoing process, and even species showing positive trends should be supported until their conservation is firmely secured. Bats are long lived animals with a slow rate of reproduction, so that environmental or human pressures can cause populations to decline very rapidly. Thus, bats species should still be considered in danger, and measures for their protection should still be taken.
Thousands of volunteer surveyors assisted in the collection of data used for the study, and many conservation NGOs, governmental organisations and individuals contributed to the development of this report. Among them, experts from the IUCN SSC Bat Specialist Group were also involved in its production.
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* Note: The study focuses on 16 of the 45 bat species found across the continent and compiles data from ten existing monitoring schemes in 6,000 hibernation sites across nine countries - Latvia, Hungary, the Netherlands, Austria, Portugal, Slovenia, Slovakia, the United Kingdom and Germany. The produced European-scale indicator of bat population trends should be interpreted cautiously at this stage, as many species and countries are yet to be represented. It is hoped that this report will lay the groundwork for an even more comprehensive study in coming years, as bats are widely monitored across Europe.