Description of colonies and samples
Five colonies of greater mouse-eared bats were investigated in South Tyrol in 2016 (Figure 1). All colonies were located in the roof of active churches and covered almost the whole region to the border with Austria. The distance between colonies, calculated along bottom valleys in order to reflect the real route of animals, ranged from 29.7 (roosts one-three) to 125.8 kilometers (roosts three-four) (Figure 1). All roosts hosted maternity colonies from late March to late September, mostly including adult females with their offspring. Adult males were sporadically sampled in all locations, particularly during the month of September (Figure S1). All colonies hosted between 1000 and 2000 animals, with the exception of the northernmost site, where we only found around 200 individuals (colony three, Figure 1). M. myotiswas often the most abundant species within roosts. However, co-roosting with the sibling species M. blythii was confirmed in all locations, especially during the mating season in September, when the relative frequency of the two species widely differed between colonies (Figure S2). In addition, a segregated aggregation of about 100 M. marginatus was recorded within colony two in May.