The little brown bat is a member of the genus Myotis, which is represented by three species in Wisconsin. This bat weighs between 5.5 and 12.5 g (0.19-0.44 oz), and individual bats' weights vary seasonally and are least in the spring as bats emerge from hibernation (WI Bat Program unpublished data). Adult forearm lengths range from 36 to 40 mm (1.4-1.6 in), and total body length is 8.0-9.5 cm (3.1-3.7 in) (Kurta 1995). Adult little brown bat wingspan is 222-269 mm (8.75-10.5 in; Barbour and Davis 1969). Body color ranges from pale tan to reddish to dark brown, and is lighter on the ventral side. Feet have long toe hairs that extend to the tips of the toes.
Little Brown Bat (Myotis lucifugus) Species Guidance
Wisconsin Department of Natural Resources (2013). Little Brown Bat (Myotis lucifugus) Species Guidance. pp 11.