Ranjena pećina cave – A new important roost site of Mehely’s horseshoe bat Rhinolophus mehelyi in Serbia

Abstract

Mehely’s horseshoe bat, Rhinolophus mehelyi Matschie, 1901, has a discontinuous Mediterranean distribution. It is considered the rarest and the most threatened bat species in Serbia. On the Balkan Peninsula it is a regular faunal element, but it was not found in Macedonia, Montenegro, Bosnia and Herzegovina, and Croatia (where previous findings have been disproved as mistakes in identification). Population in Romania has been in rapid decrease for the last 70 years, while Bulgarian one it is considered as stable and numerous in optimal cave roosts and habitats. It is highly gregarious species, forming small to mediumsized nursery, transitory and hibernation colonies, together with other medium-sized horseshoe bats. Optimal habitats are karstic arid areas. Until recently, population in Serbia was estimated to about 200 individuals, with a decreasing population trend, and the species has been assessed as vulnerable in Serbia. It was recorded at 3 localities in eastern Serbia only. Mixed hibernation colony counting around 3.000 bats of all 3 medium-sized European rhinolophid species has been discovered on 28 October 2016 in the Ranjena Pećina cave (Vratarnica village area) in eastern Serbia. The cave has a pit type entrance followed by few chambers in different horizons, and the colony was located in the second chamber. Dominant species within colony was Rhinolophus euryale with more than 2300 individuals, while rest of the colony counted around 400 specimens of Rh. mehelyi and less than 300 Rh. blasii. During the next survey visit on 4 February 2017, bats were found in the second chamber in a half of previous number, while the rest of them have moved deeper into the cave. In the first chamber of the cave 2 individuals of Rhinolophus ferrumequinum and a single individual of Rh. hipposideros have also been recorded. This record significantly contributes to the knowledge on this rare and vulnerable species in Serbia and its subpopulation(s) on the Balkan Peninsula. Monitoring of the colony, the search for summer roosts, its conservation and protection are necessary activities and important task for our future work.