Lutra 57(1)_Dekeukeleire & Janssen_2014

A large maternity colony of 85 Bechstein’s bats (Myotis bechsteinii) in an invasive tree, the red oak (Quercus rubra)

The Bechstein’s bat (Myotis bechsteinii, Kuhl 1818) is considered to be one of the rarest bat species in Flanders. The species is an outspoken woodland-specialist, and is regarded as an index species for old-growth deciduous forests (Schlapp 1990, Dietz & Pir 2009). The Bechstein’s bat shows a complex social behaviour. During the summer breeding season, the sexes live separated from each other. The bats inhabit tree cavities (mostly old woodpecker holes) and, if present, artificial bat boxes (Baagøe 2001). Females form maternity colonies of generally 15 to 45 individuals and show almost complete natal philopatry (Kerth et al. 2002). Mitochondrial DNA shows that these colonies are closed societies, consisting of only a few matrilines (Kerth & van Schaik 2012). Bechstein’s bat colonies are complex fissionfusion societies, in which....