The long-fingered bat is an insectivorous species, typically feeding on insects with aquatic larvae such as Diptera and Trichoptera, although some recent evidence suggests that it may feed opportunistically on fish (6) (7). Individuals emit short steep broadband echolocation calls, as is typical of other Myotis species, sweeping from frequencies of 90 kHz down to 35 kHz on average.
The species typically forms colonies from several tens up to several thousand individuals, usually mixed with other cave species, most commonly Miniopterus schreibersii, but also Rhinolophus euryale, R. mehelyi, R. ferrumequinum, Myotis emarginatus, M. myotis and M. blythii, but individuals can occasionally be found roosting singly on cave walls. Very few males are present in maternity colonies, which form in summer, but mixed-sex colonies exist throughout the rest of the year. Because the species is closely associated with water, it preferably roosts near water surfaces, if such locations are available.
Mating starts in August and may continue throughout the winter and possibly early spring. Bats give birth to a single pup between April and May, after a gestation period of between six to eight weeks. They are among the first European species to give birth following winter. The pup is weaned after a period of approximately four to six weeks.