Use of habitat and foraging time by females of Eptesicus nilssonii (Chiroptera, Vespertilionidae)

(Uploaded by Plazi for the Bat Literature Project) Characteristic features of summer habitat and foraging time used by female E. nilssonii of differing reproductive status have been investigated. The research was carried out in the north of Samarskaya Luka in May and July 2012–2018. Sixteen bats were captured and tagged with transmitters. Research revealed that tree hollows serve as main roosts for bats. Regular roost switching is characteristic for pregnant and post-lactating female colonies, while lactating females utilize the same roost for nearly the entire lactation period. Evening emergence of bats is highly light dependent and occurs 40 minutes after sunset on average. Female home range size is similar in spring and summer, and averages 430.7 and 401.8 ha, respectively. Regardless of the season, their main foraging sites are forest edges, clearings, and spaces along the vertical tree and shrubbery vegetation structure of the riverbank area. Pregnant and post-lactating females not caring for offspring exhibit similar duration of nocturnal activity. Lactating females forage less and in phases. In late spring, females often hunt in places located over 3 km away from daytime roosts, while in summer they usually forage within 1 km of the roost. The revealed differences in behavior of pregnant, lactating, and post-lactating females are discussed in relation to insect resources and the energy costs of foraging and feeding non-flying offsprings.