Use of synanthropic roosts by bats in Europe and North America

ABSTRACT Diurnal roosts are vital to bats and growing evidence suggests that bats increasingly exploit synanthropic structures, such as buildings. The use of synanthropic roosts (SRs) has been explained as a consequence of the decreased availability of natural roosts imposed by habitat destruction, although growing evidence suggests that the use of SRs may be beneficial to bats in many ways, including enabling the expansion of distributional ranges. Based on data from Europe and North America, our study aimed to (1) analyse the proportion of use of synanthropic vs. natural roosts, (2) test the hypothesis that bats are forced to use SRs in response to the destruction of natural habitats, (3) analyse latitudinal variation of the proportion of use of SRs and (4) address the highly contrasting pattern in the proportion of use of SRs between the two continents in the light of historical aspects of coexistence between bats and humans. We compiled published data on day roosts obtained by means of radio‐telemetry, providing unbiased evidence of the proportion of synanthropic and natural roosts. We compared the obtained patterns between the two continents, analysed the relationship between the proportion of use of SRs, land cover and latitude and analysed historical reconstruction of anthropogenic land use. In Europe ( n = 3385 roosts), SRs were used by twice more (26) bat species and were used 17× more frequently than in North America ( n = 6795). We found no support for the hypothesis that bats use SRs in response to habitat destruction. The use of SRs increases with latitude in Europe, but not in North America, despite decreasing areas of human‐altered habitats. Historical processes related to the length of coexistence between bats and humans on both continents, rather than the current state of nature, may underlie the contrasting patterns observed.