Living above the treeline: roosting ecology of the alpine bat Plecotus macrobullaris

Abstract

Littleis known about the alpinebat community, but recent studies suggest that the alpine long-eared bat, Plecotus macrobullaris, commonly forages in alpine habitats, although most of its known roosting records are from locations situated below the treeline. Aiming to contribute to resolving this seemingly contradictory pattern of ecological preferences of P. macrobullaris, we carried out a radio-tracking study to (1) identify its roosts and unveil its roosting habitat preferences, (2) determine whether bats found foraging in alpine habitats do actually roost and breed in such high-mountain environ- ments, and (3) test if any elevation-related sexual segregation occurs. We captured 117 alpine long-eared bats and radio- tracked 37 individuals to 54 roosts located at elevations be- tween 1,450 and 2,430 m, 46 of them above the treeline. Bats used rock crevices (30 roosts), scree deposits (21) and build- ings (3) for roosting, and most lactating and pregnant females relied on crevices. Bats selected areas with high meadow availability near the roost, while avoiding densely forested areas. Foraging areas and roosting sites were located at the same elevation, indicating that alpine long-eared bats use alpine areas for both roosting and foraging in the Pyrenees. Breeding females roosted at lower elevations than nulliparous females and males, though they remained above the treeline. Although being considerably different to the ecological pref- erencesdescribedsofar intheAlps,theroostingbehaviour we observed was consistent with some ecological traits, namely foragingand trophic behaviour, ofP. macrobullaris, as well as its distribution pattern linked to mountain regions.