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.
that this morning activity would end later in June and July, and earlier in August. This would contradict observations made abroad and the assumption that the seasonal changes in the amount of insect food directly influences activity. It should be remarked, however, that with the lengthening of the nights, also the nocturnal period of the bats spent in the free had also automatically lengthened. This period was 5 hours 47 minutes and 6 hours 15 minutes at the end of June, 6 hours 33 minutes in July, and between 6 hours 32 minutes and 7 hours 20 minutes at the beginning of August. By a series of observations made in the first days of August, one might assume that the rapidity of morning return is influenced also by temperature. It seems that the animals fly quicker in cold weather (see Table l), - again in contrast with G-AISlER's experiences (5) on Rh. hipposidero s . I have studied Myotis myoti s mostly at the Pisznice Cave. By direct observations, I was able to establish - and my findigs were corroborated by netting controls - that this large-bodied species leaves its daytime shelter later after sunset that both Rhinolophus euryal e and Miniopterus schreibers i , and returns as the earliest in the morning. Of all studied species, it had the shortest stay in the free. Thus a section each of the activity curves referring to the movements in the Pisznice Cave, and the finishing evening and commencing morning data of the Pisznice Cave of Tables 1 and 2, refer to this species. According to my notes taken at the Pisznice Cave, its exit began 42-43 minutes after sunset in June, and 32-40 minutes at the end of July and the first days of August. At the time of one of the surveys in June, the sky was overcast and on another the weather was clear, and while this had obviously influenced Rhinolophus euryal e, it had no role in the case of the Myoti s exemplars departing in utter darkness. One might think that, due to seasonal causes, changes may occur in the internal rhythm. I have already pointed out,
