Evaluating Transient Habitat use by Migrating Tree-Roosting Bat Species (Hoary Bats and Silver-Haired Bats)
The objective was to document activity by migrating tree bat species at INL caves in order to
identify stopover habitat to be investigated by further study. The two target species were hoary
bat (Lasiurus cinereus) and silver-haired bat (Lasionycteris noctivagans). These two species
comprise the bulk of bats killed by wind turbines, with hoary bats comprising half of known
The 2009 field season resulted in the collection of 42,978 files of bat call sequences from two INL Site caves and a single off-site cave (Crystal Ice Cave) over 93 sampling nights. Data collection during the 2010 field season continued from early September until midwinter; these data are still being analyzed. Environmental Research at the Idaho National Laboratory Site 9.15 The original intent of this work was to focus on two target species (hoary bats and silverhaired bats); however, the methodology employed at cave entrances revealed aspects of INL Site bat communities and bat behavior not previously described. Late summer and fall activity presents a mix of summer resident, transient migrators, and pre-hibernation swarming bats all converging at cave features to obtain resources. Review of call files has revealed the presence of the little brown bat (Myotis lucifugus, a species at risk from white-nose syndrome) as well as several species that may be new records for INL (Yuma myotis, Myotis yumanensis and pallid bat, Antrozous pallidus).