Fledermauskästen im urbanen Raum. Einfluss der Baumdichte und weiterer Standorteigenschaften auf die Belegrate [Bat boxes in urban areas – Influence on occupancy rate by tree canopy density and other site properties]

Sorbe, F; Buchholz, S; Straka, TM

Abstract

Given the continuous decline of potential bat roosts in urban areas, bat boxes are becoming more and more important as a possible replacement for this loss. However, little is known about the extent to which these boxes are used by bats in urban areas, since previous studies on bat boxes have been focused predominantly outside cities. In the present study, 174 bat boxes that were installed in several districts of Berlin in 2015 were investigated in 2019 to gain a deeper understanding of i) how many of the boxes were adopted by which bat species in this relatively short period of time, and ii) which variables at local and landscape level affect the use of bat boxes. During the period from May to August 2019, bat boxes were checked twice for occupancy. In addition, variables at the local (shading, number of boxes, and object to which the box is mounted) and landscape level (tree density, degree of sealing, and distance to nearest water body) were recorded. Overall, after four years, nearly a quarter of the boxes inspected (21.8%) were occupied by bats, identified by the presence of a species or bat guano. The most frequently detected species was common pipistrelle (Pipistrellus pipistrellus), with nine individuals, as well as single records of soprano pipistrelle (P. pygmaeus) and lesser noctule (Nyctalus leisleri). Increased tree density and the presence of multiple bat boxes in the near vicinity had a positive effect on occupancy probability. Boxes mounted on building facades or poles were more likely to be accepted than boxes mounted on trees or balconies.