Bat numbers in Europe soared by more than 40% between 1993 and 2011, according to European Environment Agency
In the most comprehensive study yet of European bat populations, the agency examined 16 of the 45 bat species found across the continent, cataloguing bats hibernating at 6,000 sites in nine countries, including the UK. The number of species at the sites increased by 43 % during the 19-year study.
European bat populations declined significantly during the second half of the 20th century, largely due to intensifying agriculture, changes in land use, intentional killing and destruction of roosts. The report notes that environmental or human pressures can cause bat populations to decline rapidly, while recovery is often slow.