Bat species richness and activity over an elevation gradient in mediterranean shrublands of Crete

Abstract

The effect of elevation on bat species richness and activity was investigated in shrublands of central Crete (Greece) using broad-band acoustic surveys. Recordings of echolocation calls were made in 15 transects equally distributed in three distinct elevation zones (500, 1000 and 1500 m a.s.l.) during spring and autumn 2007-2008. Time-expanded calls were subsequently identified with the use of quadratic discriminant functions. Out of 13 species recorded, Hypsugo savii, Pipistrellus kuhlii and Tadarida teniotis were the most common and abundant. Many Rhinolophus hipposideros were also recorded in all elevation zones. Thirteen species were recorded in the lower elevation zone, 7 species in the mid one and 8 species in the 1500 m a.s.l. sites. Species richness, the number of bat passes of the most abundant species, as well as the total number of bat passes were not sig- nificantly affected by elevation. In spring both species richness and bat activity were higher than in autumn, although the corresponding difference in temperature was not significant. The high variability in both bat activity and the number of species found per transect in each elevation zone probably depended on the presence of other habitat types in the close vicinity, while roost availability and location might also have played an important role. We suggest that the ability of bats to perform regular movements along the elevational gra- dient has to be taken in account when assessing elevational patterns in bat diversity and activity. The geology of the study area is also of considerable importance through its effect on foraging and roosting opportunities for bats.