Seasonal Dynamics of Occupation of Bat Boxes by Bats in Forests of South-western Poland

Phenology of occupation of summer artificial roosts (boxes) by bats was studied in forests of southwestern Poland. Surveys were performed since March till November in 2001-2005. The aim of the study was to show quantitative and qualitative seasonal variation in occupation of roosts by bats in forests. Ten bat species were noted. Most numerous were Myotis nattereri (51.5% of all individuals), Plecotus auritus (27.9%), Myotis myotis (9.6%), Pipistrellus nathusii (6.6%) and Nyctalus noctula (3.6%). The remaining species (Myotis mystacinus, Myotis brandtii, Nyctalus leisleri, Eptesicus serotinus and Pipistrellus pygmaeus) constituted less than 1% of all noted bats. The percentage of occupation of boxes varied between March and November (with maximum in the second half of this period) as did the density of individuals (with maximum in July or August). Differences in the number of bat species recorded in boxes were also observed in each phenological season.