O. G. Dely szerk.: Vertebrata Hungarica 8/1-2. (Budapest, 1966)

Topál, Gy.: Some observations on the nocturnal activity of bats in Hungary 139-166. o.

species

. The paper contains yet data on the nocturnal activity of Hiniopterus schreibers

i, Eptesicus serotinu

s, Nyctalus lei3ler

i

, and Myotis emarginatu

s

. The observations of the returning flight at dawn show that, in the Pisznice Cave, Rhinolophus euryal

e, Myotis myoti

s , and Miniopterus schreibers

i occupied their daytime shelter earlier In August than in the preceding periods of the summer. It is indisputable that in the case of Rhinolophus euryal

e , active from relatively early times till late in the morning, light intensity as a factor determining activity plays an important role. Our data unequivocally prove that the species begins its nocturnal hunting flight later in clear weather and earlier under an overcast sky. On the other hand, the situation seems to be qualitatively different for Myotis myoti

s, departing in utter darkness and returning very early during the night: a species uninfluenced by the state of the sky. In the evolvement of its daily rhythm, light may directly Influence only populations occupying semidark shelters. At least for certain phases of the year, the preceding statement holds also for Miniopterus schreibers

i, living exclusively in caves. Of the other environmental factors, temperature seems to affect the rapidity of the return flight in the morning. The above results are completely new in Hungarian literature, and are unique from the point of view of referring to the observation of several species simultaneously in one locality.We had no data on the nocturnal activity of several (

Rhinolophus euryal

e, Miniopterus schreibers

i, Nyctalus leisler

i, Myotis emarginatu

s) of the species studied.