Bats of the United States and Canada

Evening Bat, Nycticeius humeralis

134 bats of the united states and canada EVENING BAT Nycticeius humeralis Weight is 7–14 grams (0.2–0.5 ounce); wingspan is 26–28 centimeters (10–11 inches); distribution is most of the eastern United States and northeastern Mexico. This species usually inhabits tree cavities or buildings in summer. In the Southeast, it may share roosts with the Brazilian free-tailed bat. It almost never enters caves, although it sometimes joins the bats swarming about certain cave openings in late summer. Maternity colonies in buildings sometimes contain hundreds of individuals. Smaller colonies may occur behind loose bark of dead pines and in hollow cypress trees. Winter habitat is almost completely unknown, but evening bats accumulate large reserves of fat in autumn, sufficient for either hibernation or a long migration. This species emerges early and flies a slow and steady course. Heavy rain and cold temperatures retard activity, and females nursing young return to the roost periodically to care for their offspring. The evening bat consumes a variety of small insects. Babies are born in nursery roosts sometime between mid-May and mid-June. The usual litter size is two. As with most other species of bats, birth is by breech presentation (i.e., the tail-end exits the birth canal first). After the babies are born, they grasp a nipple within 5–8 minutes. Newborns are pink, except for slightly darker feet, membranes , ears, and lips; their skin is so transparent that the viscera can be seen. Lifespan is greater than 5 years. Although less common through most of its range, it is one of the most common bats throughout the southern coastal states. recto runninghead 135 ...