First data on parasites from bats (Chiroptera) in Karelia are presented. Bats were captured at hibernacula in Lahdenpohsky and Sortavalsky Districts of Karelia in March 2010 and February 2011. Partial helminthological dissection was applied to 12 bat individuals of three species: northern bat Eptesicus nilssonii Keyserling & Blasius, 1839 (8 specimens), brown long-eared bat Plecotus auritus (Linnaeus, 1758) (1 spm.), and Brandt's bat Myotis brandtii (Eversmann, 1845) (3spm.). Ectoparasites were collected from the bats captured in March 2010: E. nilssonii -6 individuals (3 from each of Sortavalsky and Lahdenpohsky Districts), P. auritus -1 ind. (Lahdenpohsky District), M. brandtii -1 ind. (Sortavalsky District). The surveys revealed 14 species of parasites from different taxonomic groups. All the parasites were found in Karelia for the first time. Helminthes were represented only by trematodes of 3 families: Plagiorchiidae (Plagiorchis vespertilionis, P. koreanus, P. muelleri), Lecithodendriidae (Lecithodendrium linstowi, Paralecithodendrium chilostomum, P. skrjabini), and Pleurogenidae (Parabascus magnitestis). Ectoparasites in the samples include gamasid mites of the families Spinturnicidae (Spinturnix kolenatii, S. plecotinus) and Macronyssidae (Macronyssus crosbyi, M. cyclaspis), chigger mites of the family Trombiculidae (Leptotrombidium sp.), and fleas of the family Ischnopsyllidae (Ischnopsyllus hexactenus, Ischnopsyllus sp.). All the parasites are bat specialists, known to occur in various parts of Russia and Europe.

The article deals with the least studied systematic group of mammals of Karelia-bats (Chiroptera, Vespertilionidae). The aim of the study was to determine the status of the species in the process of their inventory by traditional and modern research methods. For the first time the comprehensive assessment of the species composition, relative abundance (%) and relative number (ind./km of the route) of bats during the period of hibernation and their summer activity in Karelia is presented. Monitoring of winter underground shelters was carried out in 2009-2018. It was shown that five species of bats winter in Karelia; they are the northern bat, the Brandt's bat, the whiskered bat, the Daubenton's bat, the brown long-eared bat. The northern bat predominates: its relative abundance is 65.3 %. In the summer the common noctule parti-coloured bat, the Natterer's bat and the pond bat were registered in addition to wintering species mentioned above. It was done the road routes in the latitudinal direction using static ultrasound detector Song Meter SM2 Bat+ and Kaleidoscope Pro (ver. 3.1.1.) software on. In the summer surveys the northern bat dominated: its relative abundance is 70.4 %, relative number-0.413 ind./km of the route. It was registered up to 66°11'N. Other species are much less common, the northern boundaries of their registration are located southwards, and their relative number is 0.001-0.028 ind./km of the route. Studies showed the absolute dominance of the northern bat in bat communities, both in wintering and during in summer activity. Northern boundaries of the species registration were determined. It changes the old ideas about their distribution and spread in the European North of Russia.