Habitat selection and activity patterns in the greater mouse-eared bat Myotis myotis

Abstract

The habitat preferences and activity of greater mouse-eared bats were investigated by means of radio-telemetry in two regions in Upper Franconia (Bavaria, Germany) that are characterized by a mosaic of deciduous forests, coniferous forests and woodless areas. In one case bats roosted in a maternity colony from which they visited foraging habitats up to 10.8 km away; in the second, the bats started in a cave which served as a night roost. These bats foraged around the cave up to 2.5 km away. Mean size of foraging areas was 13.1 ± 4.6 ha. Most of the bats used several foraging areas per night (mean 5.1, range 1-10). Hunting time per foraging site ranged from 5 to 224 (median 25) minutes. Foraging habitats in some individuals remained constant over two consecutive years. The bats hunted almost exclusively in woodland (98% of the hunting time) with a significant preference for deciduous forests as opposed to coniferous forests. The preference for deciduous forests as foraging habitats is likely to be caused by: (1) a higher density of suitable prey animals and (2) a better accessibility of the ground-dwelling prey due to the lack of ground vegetation. The mean time span between emergence from the roost and return lasted about 5.5 hours. On average, 79.9 ± 9.0% of that time the bats spent flying. They behaved like other gleaning bats and did not show distinct activity peaks. The proportion of commuting flights (between roost and foraging area and between different foraging sites) added up to about 19% of the flight activity whereas the rest of the time in flight was spent hunting. Interruptions in the hunting activity occurred regularly, about five times per night and bat. These breaks lasted 1 to 130 (median 10) minutes and were spent in temporarily used night roosts and on perches. The bats hunted mainly during slow flight, but we also found evidence for hunting from perches on tree trunks as an additional foraging strategy. © Museum and Institute of Zoology PAS.