Plecotus townsendii is a medium-sized bat with forearms measuring 39 to 48 millimeters (mm) long and weighing 7 to 12 grams. Total body length is 98 mm, the tail is 46 mm, and the hind foot is 11 mm long. This bat's long ears (over 2.5 centimeters) and facial glands on either side of the snout are quite distinctive. Fur is light to dark brown depending upon the age of the individual and the subspecies. The only other eastern bat that resembles the Ozark or the Virginia big-eared bat is P. rafinesquii (Rafinesque's big-eared bat). Rafinesque's big-eared bat has toe hairs that extend beyond the end of the toes and the dorsal fur is gray rather than brown. The belly fur of Rafinesque's big-eared bat is white or whitish rather than light brown or buff (Schmidly 1991, Barbour and Davis 1969). The Ozark and Virginia big-eared bats do not have overlapping ranges. Copulation occurs in the fall and winter and the females store the sperm until ovulation in late winter or spring. Gestation takes about 3 months and a single pup is born in May or June. Development is fairly rapid and the young are on their own within 2 months (Barbour and Davis 1969, Schmidly 1991, Kunz and Martin 1982).