Observations made at three church bat (Chiroptera) roosts in central Slovenia

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Church buildings in Slovenia have long been known as suitable nursery roosts for several bat (Chiroptera) species (Presetnik et al. 2009), which require a warm environment to raise their young during the summer.Knowing which churches are utilized by bats as roosts is therefore highly important for bat conservation.During late spring and early summer of 2020, we visited three church roosts of lesser horseshoe bat (Rhinolophus hipposideros) in the Savinjska region, Central Slovenia.These churches were St. Neža at Liboje, St. Magdalena on Hom hill (Matke) and Sts.Mohor and Fortunat on Šmohor hill (Tab.1), which had been inspected in the past (Hercog 2013, own data) and are known to host larger roosts of the species.We decided to inspect these churches to record their present status and to assess the current size of their respective reproductive colonies.
Bats were counted when exiting the roost in the evening.Each roost was inspected twice -initially, a preliminary evening visit was made to assess flight patterns and emergence openings, and later a thorough count of emerging bats was conducted.The count began 5-10 minutes before sunset with bats being counted until 15 minutes after the last confirmed emergence from the roost.
R. hipposideros were identified using a heterodyne ultrasound detector (D200, Petersson Elektronik) at 110 kHz, while additional detectors were used to search for other possible bat species.Since female R. hipposideros near our survey area were noted to give birth from mid-June onwards (Hercog 2013), we assumed all emerging individuals of the species were adults.On 25. 6. 2020 (Tab. 1) we also deployed hand nets at St. Magdalena Church in order to determine one of the species present there, using determination key in Dietz & Kiefer (2016).
Apart from confirming R. hipposideros presence during all our surveys (Tab.1), we recorded two other bat species -the greater horseshoe bat (R. ferrumequinum) and the whiskered bat (Myotis mystacinus).We also noted individual bats which we were unable to distinguish to species or even family level, including an individual of a large bat species at Sts. Mohor and Fortunat (Tab.1).Almost all bats used small windows and other apparent holes for their emergence, except for unidentified Vespertilionidae individuals at St. Neža, which emerged from slits between stone roof tiles of the bell tower.
(Petrinjak 2009, Presetnik 2018)h had only been surveyed once in the past, when the first author of this contribution inspected the roost on 24. 8. 2017, observing 123 R. hipposideros of unknown sex and age, 28 adults, 38 juveniles, 2 adult females and one carcass.These numbers, combined with our recent findings of 217 adults, make this church a nursery roost with a very large maternity colony of the species in Slovenia(Petrinjak 2009, Presetnik 2018).St. Magdalena on Hom hosts an even Site [lat.(°N), long.(°E), m a.s.l.]