Foraging ecology of long-legged myotis (Myotis volans) in North-Central Idaho

Limited information exists on the foraging ecology of the long-legged myotis (Myotis volans), especially with regard to use of available foraging habitats in large, relatively contiguous forested landscapes. During the summers of 2004 and 2005, we radiotagged adult long-legged myotis (n = 70) in north-central Idaho to estimate the size of home ranges and to evaluate use of available foraging habitats. Size of home range and core areas was measured for individuals with ≥31 locations (n = 30) using the adaptive kernel method, and selection among available foraging habitats was evaluated using Euclidean distance analysis. Home-range estimates did not differ among males, pregnant females, and lactating females (P = 0.52). Core-area estimates also did not differ among males, pregnant females, and lactating females (P = 0.62). Second-order habitat analysis, based on vegetation, showed that home ranges of males (P = 0.01), pregnant females (P = 0.001), and lactating females (P = 0.001) all were closest to stands of medium-diameter trees, that is, trees predominantly 12.7-38.0 cm diameter at breast height (dbh), that also contained larger snags typically used as roosts (X̄ = 54.0 cm dbh; n = 100). Second-order habitat analysis, based on slope position, showed that home ranges of males (P = 0.0001), pregnant females (P = 0.001), and lactating females (P = 0.001) were closest to mid-slope positions. Third-order habitat analysis, based on either vegetation or slope position, did not differ from random use for males, pregnant females, and lactating females. More lepidopterans were captured in black-light traps at mid-slope positions than either upper or lower slope positions. Fecal pellets (n = 171) from 62 long-legged myotis revealed a diet primarily composed of Lepidoptera (49.2% volume, 100% frequency) and Coleoptera (31.1% volume, 100% frequency). Examination of our data demonstrates the importance of forest stand structure, topographic position, and abundance of moths in foraging habitat for long-legged myotis.