Bat activity above 3000 m in the Austrian Alps (Hoher Sonnblick, 3106 m)
Karin Widerin, KFFÖ - Austrian Coordination Centre for Bat Conservation and Research, Leonding (AT)
During the last few years (2013 to 2015) we investigated the migratory behaviour of bats throughout the Alpine Arch. A rather surprising result was that a large number of bats crosses the Alps up to an altitude of 2500 m. Subsequently, we wanted to know up to which altitude bats can be detected in the Central Alps. Thus, we investigated bat activity on top of Mt. Sonnblick at an altitude of 3106 m.a.s.l. in the years of 2014 and 2015. This mountain top is situated in the South of the province of Salzburg and it is part of the main Alpine Arch. Extreme weather conditions, glaciers and rocks with very rare fragments of vegetation characterize the investigated site and hence, this habitat seemed totally unsuitable for bats. Bat activity was monitored by automated recording of bat calls (batcorder, ecoObs, Nuremberg) during September and October 2014 and permanently from March to November 2015. Contrary to our expectations we found bat activity from mid-April to mid-September. There was a little peak of activity in spring, however, the main activity was detectable during August and September. Among the recorded species were all long-distance migrants of Europe, namely Kleiner Abendsegler (Nyctalus leisleri), Großer Abendsegler (Nyctalus noctula), Rauhautfledermaus (Pipistrellus nathusii) and Zweifarbfledermaus (Vespertilio murinus), but also sedentary species like Nordfledermaus (Eptesicus nilssonii) and species with more or less unknown migratory behaviour like Mückenfledermaus (Pipistrellus pygmaeus ) were found. Bat activity was strongly linked to milder weather conditions, but activity was still found at relatively high wind speeds and temperatures as low as -2,5°C.