Importance of urban trees and buildings as daytime roosts for bats

Abstract

AbstractRoosts are a very important resource for bats, and often play a central role in conservation projects. To evaluate the feasibility of identifying urban bat roosts, we trapped 30 individual bats from seven species, attached radio transmitters and located their daytime roosts. This enabled us to build hypothesis on the importance of trees and buildings as daytime roosts for urban bats. None of the captured animals were reproducing or lactating, so we assumed all recorded roosts to be simple daytime roosts. Of the 30 marked bats, 18 individuals (six species) could be monitored, and a total of 114 roosts were located; 57 of which were in trees, and another 57 in buildings. Our results indicate that neither building condition nor green coverage in the immediate (≤ 20 m) surroundings of a building was a significant predictor for the presence of roosts in or on a building. For tree roosts, diameter at breast height (DBH) was the most important factor determining the choice of tree roosts, but was found insignificant in a Generalized Linear Mixed Model. We presume that the lack of significance regarding green coverage and DBH in the model can be explained by the limited sample size of our study.