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 the results, with regard to fluctuations in the intensity of light could, in want of instrumental readings, still he somewhat comparable, I used as the basis of calculations the official sunrise and sunset data according to the Central European Mean Time given for Budapest. I have accordingly converted my data obtained before 1958 (recorded during the Daylight Saving Time in use at that period). The differences inherent in the diverse geographical and cardinal location of the diverse localities of observations, as well as those referring to the plant cover of their environment, are, as well as possible, given in the defiled description of the localities. Concerning the meteorological factors, I have several times noted my subjective observations on the clouded or unclouded state of the sky. Temperature, and air motion had also been recorded. Different tables give the main data of the evening (Table l) and morning (Table 2) surveys. Description of the daytime shelters and their populations Pisznice Cave (18

o?0» E, 47°42' N; 500 m a.s.l.). The opening is in a rocky slope covered with sparse woods, inclined towards the SW. In a circle of about a 5 km radius, and also in the further neighbourhood, it is largely covered by forests.A larger body of water is the Danube to the N-ÏTW, about 7-8 km away. The cave proved to be excellently suitable for observations of this kind, since standing at the 180 cm high and hardly narrower entrance, one can take a position so that the bats pass at eye-level when departing from their daytime shelter or returning to it. Hence the immediate nearness of the observer allows not only the noting of their movements but the differences in size can also be excellently observed.