Emergence and flight routes of the lesser horseshoe bats Rhinolophus hipposideros (Bechstein, 1800) from a church at Ljubljansko barje, central Slovenia

Abstract

The flight routes from roosts to feeding habitats are important for efficient conservation of bats, but in Slovenia they are poorly known. Emergence and flight routes of the lesser horseshoe bats Rhinolophus hipposideros from the Church of Sveti Duh at Vnanje Gorice, Ljubljansko barje, were monitored on ten different days in August and September 2009. In the beginning of August, 72 lesser horseshoe bats were counted in the attic; the number decreased to 29 in the beginning of September. Individuals of three other bat species were also found in the attic and belfry: the greater mouse eared bats Myotis myotis, serotine bats Eptesicus serotinus and a group of alpine long-eared bats Plecotus macrobullaris. The lesser horseshoe bats emerged only from a single opening in the attic. The first bat flew out on average 16 minutes after the sunset, while the first bat amongst those that did not return to the roost left on average 20 minutes after sunset. The lesser horseshoe bats flew few metres above the ground into the nearby forest Gulč on the northwestern side of the church. We observed flying bats at nine locations in this forest and at three locations on the forest edge, where they probably foraged. Bats flew along a lit road next to houses, close to a major road they had to cross, and next to a railway southwest from the church. The spatial and temporal distribution of observations indicated the flight towards the mixed forest Plešivica, where a lesser horseshoe bat was observed app. 1.7 km bee-line distance SW from the church at Vnanje Gorice. Considering that bats generally follow linear elements in the landscape, and on the basis of our observations at 21 locations and flight behaviour we envisaged the most likely course of their flight route. These data are important for efficient conservation of the lesser horseshoe bats roosting at Vnanje Gorice and maintenance of important landscape elements in the surrounding landscape.Letalne poti iz zatočišč do prehranjevalnih habitatov so pomembne za učinkovito varstvo netopirjev, a so v Sloveniji večinoma slabo poznane. V okviru naše študije smo deset dni v avgustu in septembru 2009 spremljali izletavanje in letalne poti malih podkovnjakov Rhinolophus hipposideros iz cerkve Svetega Duha v Vnanjih Goricah na Ljubljanskem barju. V začetku avgusta je porodniška skupina malih podkovnjakov na podstrešju štela 72 osebkov in se do začetka septembra zmanjšala na 29 osebkov. Na podstrehi in v zvoniku so bili najdeni še navadni netopirji Myotis myotis, pozni netopirji Eptesicus serotinus in skupina usnjebradih uhatih netopirjev Plecotus macrobullaris. Mali podkovnjaki so izletavali le iz ene okrogle line na podstrehi. Prvi netopir je v povprečju izletel 16 minut po sončnem zahodu, medtem ko je prvi izmed tistih, ki se niso vrnili v zatočišče, izletel iz line povprečno 20 minut po sončnem zahodu. Mali podkovnjaki so leteli nekaj metrov nad tlemi v gozd Gulč na severozahodni strani cerkve. Prelete malih podkovnjakov smo zabeležili na devetih lokacijah v gozdu Gulč in na treh lokacijah ob gozdnem robu, kjer so se verjetno prehranjevali. Opazovali smo jih med letom ob osvetljeni cesti blizu hiš, blizu večje ceste, ki so jo morali prečkati, in ob železnici jugozahodno od cerkve. Ob upoštevanju časovne in prostorske razporeditve opažanj kaže na let v smeri mešanega gozda Plešivice, kjer smo zaznali prelet malega podkovnjaka približno 1,7 km jugozahodno od cerkve v Vnanjih Goricah. Na osnovi opažanj na 21 lokacijah in smeri leta ter upoštevajoč ugotovitve, da netopirji v splošnem sledijo linearnim elementom v krajini, smo poskušali ugotoviti  najverjetnejšo letalno pot malih podkovnjakov. Ti podatki so pomembni za učinkovito varstvo malih podkovnjakov v Vnanjih Goricah in za ohranitev ključnih elementov v okoliški krajini.