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.
the observation made on 20 June that the activity of the animals was undisturbed by the afternoon shower, and though it cleared up in the evening, it also became colder. On the next evening,another rainstorm began at the onset of flight, and one could clearly see that many bats had again retired due to the rain. There were several rainfalls during the night, and a severe storm arose. On the third day, however, the departure of the bats began 7 minutes later than expected (22 July); weather conditions of the past few days had clearly influenced or inhibited the normal daily rhythm. The fact that the process of activity had on this day taken more than three times as much (cf. Table l) can probably be explained partly also by this assumption, but the white light used at that time might also have had a retarding effect. The morning activity of Myotis myoti s was studied only at the Pisznics Cave. Table 2 contains the data referring to the commencement of the return flight. In the followings, I shall compare only those days of observation when survey was began also at precise times,as visible also from the graphs. It is to be seen that, on the milder June and July days, the Myoti s population began its return flight 110-107 minutes before sunrise, whereas 122-130 minutes before dawn on the colder August mornings. According to my notes, the morning return took about 70-80 minutes, and was already finished about an entire hour before sunrise. The precise establishment of the and of the return flight was rather difficult due to the presence of the other species. KOLB (8) found that the occupation of the daytime shelter lasted for 60-75 minutes.. This period is probably dependent also on the individual number of the population, but this number is less significant in the case of a larger opening than in cases when the bats have to return through smaller crevices, Miniopterus schrelbers i was found almost invariably in the presence of other species, and this made exact observations difficult.
