Bat diversity and activity at subalpine grasslands of Varnous and Triklarion Mountains (NW Greece)

Habitat use by bats at high altitudes and particularly subalpine grasslands, is poorly known. Many bats are killed through collision with wind turbines installed on or near mountain tops, showing the need for bat diversity and activity surveys in high altitude areas, especially where wind farms are installed. We studied bat use of subalpine grasslands and beech forests near the tree line, in and near Prespa National Park, NW Greece, mostly at sites where large-scale wind farms have been, or are planned to be, constructed. We applied acoustic transects, point sampling and mist-netting in 2009, 2010 and 2011 in four areas. Both bat diversity and activity were high; we recorded 14 species: Tadarida teniotis, Miniopterus schreibersii, Pipistrellus pipistrellus, P. nathusii, P. kuhlii, Hypsugo savii, Nyctalus noctula, N. leisleri, Myotis mystacinus, M. nattererii, M. blythii, Rhinolophus hipposideros, R. ferrumequinum and R. blasii. These include species at high risk of collision with wind turbines. More species may be present. Two of the sites are heavily used by commuting and foraging bats in summer; in autumn there is still some activity even on cold nights. Our results show that high altitude areas may support important bat fauna, and suggest that the establishment of wind farms may increase bat mortality, as elsewhere in Europe. To reduce potential impacts on bats, long-term pre and post-construction monitoring surveys are of fundamental importance at sites where wind farms are planned or established. The importance of subalpine grasslands for bats should be further assessed through long-term research studies.