Absence of winter records, known long distance movements of parti-coloured bats ringed in North-eastern (NE) Europe, and some observations of seasonal concentrations of migrating animals had enabled to consider Vespertilio murinus, until quite recently, as a migratory species wintering outside Ukraine and NE Europe as a whole. During the last years the species had been found in the winter season (November - middle March) in Ukraine in 14 provinces and in the AR Crimea: contact records in 7 provinces, observations of autumn display song in 9 provinces and in the AR Crimea. Analysis of the data allows to assert that at present the whole territory of Ukraine belongs to the winter range of V. murinus. New winter records of V. murinus from Ukraine and other countries of NE Europe should probably be considered as an evidence of the expansion of the species’ winter range, that may be conditioned by the appearance of big massifs of rock-like structures (= multi-storey buildings) in plain regions.
We analysed the sex and age composition of a large colony of Nyctalus noctula (605 specimens), wintering in Kyiv, Ukraine. Age was identified in 113 individuals using the method of counting growth layer groups in dentine. Males contained ca. 70 % both in the colony and in the sample of animals with the estimated ages. Males and females of all ages were in good body condition. There were bats from 0+ to 7+ years old in the sample. In males, 0+ age class was represented by 38 %; 1+ class, by 20 % of individuals. In females, 0+ and 1+ year old individuals were found in similar numbers: 29 % and 32 % correspondingly. The observed sex ratio and proportions of males and females across age classes cannot be explained only by demography. The data are interpreted in terms of migratory behaviour and mating strategy of the species: the unusual female age structure is possibly due to age-specific preferences in wintering habitat selection and search for potential mating partners.