Little Brown Bat

Myotis lucifugus


• Mating: Polygamous

• Peak Breeding Activity: September and October

• Gestation Period: 50-60 days

• Young are Born: May and June

• Number of Litters per Year: 1. Young bats are called pups and they are dependent on their mothers.

• Migration Pattern: Both year-round resident and migrant. Little brown bats live in colonies. They home in on site specific locations to live. Little is known about the dispersal of young.

• Feeding Periods: One hour or two after sunset and before sunrise

• Typical Foods: Insects, especially small-bodied aquatic insects (caddis-flies and mayflies), moths, leaf hoppers, and plant hoppers.


Its name goes a long way toward describing its appearance. Its fur is uniformly dark brown on the upper parts, with slightly paler, grayish under parts. The wing membranes are dark brown. The bats are between 4.6 to 5.6 inches long and weigh 0.19 to 0.34 ounces. Their total wingspan is 8.7 to 10.6 inches wide.

Habitat and Habits

There are two primary types of habitats for many bats: hibernation sites used during the winter (e.g., caves, mines) and roosting sites for reproduction (e.g., tree cavities) during the summer.

Reproduction and Care of the Young

Breeding takes place during the late summer and early fall during a behavioral phenomenon known as “swarming.” At this time, large numbers of bats visit and congregate in a succession of caves just prior to hibernation. Although sperm is transferred to the female during copulation that occurs in the fall, ovulation and fertilization of the egg are delayed until the females arouse from hibernation the following spring.

During the summer, females form maternity colonies, mostly in man-made structures, although some will roost in tree cavities or under the peeling bark of dead trees. Summer roosts are typically warm and relatively dark.