Decline in animal population and biodiversity caused by habitat deterioration is a serious environmental issue in agricultural landscapes. Although studies regarding habitat selection by animals have been conducted, they have often yielded inconsistent results because of differences in their focal spatial scales. We investigated habitat selection by two sympatric Myotis species (M. gracilis and M. daubentonii) at two different spatial extent scales: home-range and the foraging habitat. We radio-tracked ten adult females of each species for an average of four nights during May to September in 2006 and 2007. Bat activities were traced on a GIS-based land cover map that was comprised of seven land cover types (urban, arable, grassland, coniferous forest, deciduous forest, riparian forest, and stream). Their home-range (100% MCP) was also estimated. We compared the amount of each habitat type within the home-range to those within potential home-ranges randomly created using a 95% confidence interval.
Results/Conclusions
There was no inclination to a particular land cover type as a whole for either species, although some bats had many streams within their home-range. While the amount of forests (deciduous and riparian) and streams were strongly related to the foraging habitat of M. gracilis on all grain sizes, the most significant grain size explaining their foraging habitats was 50m. The foraging habitats of M. daubentonii were best explained by applying the grain sizes of 50 and 150m, which were associated with streams and riparian forests. Streams constituted the most important land use type to explain the foraging habitats of M. daubentonii throughout all grain sizes. The different home-range and foraging habitat selections by bats indicate that their habitat selection is scale-dependent. These results suggest that conservation efforts to preserve bat populations could be more focused on the foraging habitat range represented by small grain size, rather than on landscape management of the entire home-range. Furthermore, the two bat species selected stream and riparian forests as essential foraging habitats regardless of the grain size, although the two showed a different preference for other types of foraging habitats. Thus, conservation of the stream and riparian ecosystem is critical for these two bat species.
