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.
stop, or the entire activity "became unduly protracted in time. However, the animals were hardly, or less, alarmed when I placed a suitable thickness of red paper on the glass of the torch, and thus I used red light after the technique of KOLB (8). At dawn, the light of the lamps had perceptibly never disturbed the returning bats. One of the chief purposes of my studies was the establishment of the number of the given population, as well as to find a relationship between the population number and the intensity of activity measured at different points of time. The establishment of the numbers had in certain cases made possible the drawing of inferences within a single locality on the differing behaviour of the diverse species. If the changes in time of the activity be plotted on a graph (cf. Table 1 and 2), there are often definitely devided curves received. The counting of such relatively not too large, maximum 3500, populations was not technically difficult, because it is seldom that more than a hundred animals pass through in a minute. However, solitary work proved to be insufficient. At first, I noted the time that elapsed (see Figure 2, 8 Aug., 1955) during the emergence or return of a given amount (e.g. 100) of bats, but considerably more adequate and precise results were received if the number of animals passing through the entrance of the shelter was established during a minute. This necessitated an assistant who measured time and signalled the passing of a minute, whereas I gave him the number of animals counted during this period and he noted it down. + I should like to thank also here the help of J. TOPÁI, M. EŐRY, E. SCHMIDT, and I. SZABÓ, as rendered in the technical phase of the work.
