Species composition and activity of bats flying over rivers in the Bialowieza Primeval Forest

Bats were netted at two sites over the forest rivers Narewka and Hwoźna in Białowieża Primeval Forest (E Poland), during the summer of 1994 and 1995. A total of 452 bats of 11 species were captured. The number of bats netted each night was positively correlated with the minimum air temperature. The rate at which the three commonest species - Nyctalus noctula, Myotis daubentonii and Nyctalus leisleri - were caught varied significantly through the night, with a major peak after sunset. For N. noctula air temperature was apparently positively related to the size of the morning peak.