O. G. Dely szerk.: Vertebrata Hungarica 4/1-2. (Budapest, 1962)
Topál, Gy.: A magyarországi denevérek ivararánya 141-163. o.
strikingly small number of males were found /Table III./. And, in the summer populations of Miniopterus schreibers i, the number of males were, in certain localities, always smaller as related to the sex ratio of the hibernating populations /Table VI./. Young males, at the time of bearing, made out 45 per cent of the newly born population of Rhinolophus euryal e, 53-56 per cent of Myotis myoti s, and 39 per cent of Myotis emarginatu s . The number of young males displayed a decrease later,but this decline is not to be explained unequivocally /Table IV./. In a small Fipistrellus pipistrellu s population, 11 per cent of the young animals were males. This can be accounted for by the juvenile males having left sooner the nursing colony. The examination of winterquarters will generally render a correct picture of the sex ratios of a population inhabiting a given larger area. One must take into account ,however , the time of observation and climatical conditions. A larger activity of the males of some species is due to the fact that they retire to their winterquarters in the autumn later than the females, and are also leaving them earlier than the latter ones. This is demonstrated by observations, during several years, of Myotis oxygnathu s , but, probably due to climatic differences ,the phenomenon cannot be shown in every year /Pig. 1/. The decrease in the relative numbers of the males of that species, in the course of the years of study, is a phenomenon unexplained as yet /Pig. 2/.Author also deals with the different mortality ratios of the males and females of Myotis oxygnathu s /Pig. 2/ and Miniopterus schreibers i . The increased mortality of females is seen especially in the first year subsequent to the ringing /the destruction therefore of the younger females/. The percental ratios of the males, computed from the averages of the significant winter populations, are as follows: of 316 Rhinolophus ferrumequinu m 78,5 per cent were
