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.

finite remarks also on the clouded state of the sky, we soon find the cause of the phenomenon. For instance, observations, 1 !c by an overcast sky on 18 June, 1957, and in clear o

n 20 June, 1957, refer quite clearly to the importance ;î a clouded sky, hence the intensity of light, in • life of Rh. euryal

e. My data derive from a comparatively short period of the annual cycle, hence they are too intermittent to submit, as •vas done by several authors abroad, informations on eventual seasonal deviations. On 20 June, the animals commenced their evening departure 24 minutes after sunset just as, with some truly insignificant differences

,on the two days of observations at the beginning of August, namely 22 and 27 minutes after sunset in slightly cloudy, respectively clear, weather. Concerning morning activity, I obtained data only at the Pisznice Cave (Table 2 and Figure 2). Due to the presence of the other species, the commencement of their return could not be established precisely. A more thorough examination of the activity curves will

, however, give certain implications. At the end of June, when the numbers of the summer populations have not yet

•decreased and the majority of the Rhinolophu

s individuals were gravid (!!), I noted a definite minimum level about 3 a.m., (0300), and then the bats returned again in smarms (cf. Table 2: 19 and 21 June, 1957). On the two completely similar two graphs, this break is obviously coincident with the activity of the last returning bats. At the end of July (22 July, 1958), the separation is not as sharp in the curves, and on the mornings of the first days of August I obtained almost uniformly one-peaked activity graphs. The decrease in numbers of the population in the Pisznice Cave at the beginning of August can be ascribed, aside of the diminishing numbers of Myotis myoti

s, to the autumnal departure of mainly Rh. euryal

e. This species finished the occupation of its daytime shelter 11-24 minutes before sunsrise. Some data would imply