Little Brown Bat: Myotis Lucifigus

The Little Brown Bat, Myotis lucifigus, is a small bat, as its name implies. It is a mammal and, like all bats, it is the only mammal that can fly. Fossil records indicate that bats have been in existence for 50 million years. Little Brown Bats are between 4 ½ and 5 ½ inches long and have a total wingspan between 8.7 and 10.6 inches wide. Little Brown Bats weigh only between 0.19 and 0.34 ounces. The upper part of its fur is dark brown, and the lower parts are a light gray color. The wing membranes of the Little Brown Bat are dark brown.

They are nocturnal animals, so they are more active at night. Little Brown Bats use echolocation, or biosonar, to “see” at night. They send out signals, and use the echoes of the signals to locate objects, including food. They use the echoes to navigate, so they don’t run into things. Little Brown Bats have large ears and very sensitive hearing.

Little Brown Bat Habitat
Little Brown Bats live in the north from Canada to Alaska, and as far south as the Appalachians. They are located in most states, with the exception of Texas, California, and Florida. Little Brown Bats prefer to live over wetlands, where the water is still and the insects are plentiful. Trails, streams, and rivers provide Little Brown Bats with corridors that make navigation easier for them. They often follow the same flight plan each night for hunting. Female Little Brown Bats roost in attics, sheds, and barns during the summer as part of a large maternity colony. The heat helps the babies stay healthy.

Males form much smaller colonies, and they tend to roost in the cavities of trees rather than buildings. The males and the females do not roost together; bats found in houses and buildings are almost always part of a maternity colony of females. Little Brown Bats hibernate for the winter. They usually hibernate in mines or caves in areas such as New Hampshire, New York, Massachusetts, and Vermont. They need to hibernate in very humid areas because of the loss of moisture they experience during hibernation. Ideally, the cave should be a constant 40 degrees Fahrenheit throughout their hibernation period. Little Brown Bats that live in the southernmost states may not hibernate during the winter; they can stay in their roost year round.

What Do These Bats Eat
Little Brown Bats eat insects, including mosquitoes, beetles, wasps, and mayflies. They can eat up to 50% of their bodyweight each day. Females who are pregnant or nursing will eat more than ½ their bodyweight in insects per day. It is because of the amount of insects they eat that Little Brown Bats are considered beneficial because they eat beetles and other insects that lay larvae that can ruin crops. Little Brown Bats eat twice a day; an hour or two before dawn and an hour or two after dusk.

Little Brown Bats use echolocation to find insects to eat. They are not blind, they can see fine, but his helps. They send out signals and listen to the echoes to locate the insects. Although they may swoop towards an animal on occasion, they are only after the insects that are buzzing around the animal. They also use echolocation to locate ponds and other areas of still water. Still water is preferable to running water because there are more areas of stagnant water that draw insects.

Mating Habits
Little Brown Bats are polygamous, and they reach maturity between 6 and 9 months old. They mate in the late summer to early fall, prior to hibernation. The mating, or swarming as it is called, occurs in caves and involves large numbers of bats. However, the female bats store the sperm until they wake from hibernation, and they use the sperm to fertilize an egg in the spring. Each female Little Brown Bat has one baby, or pup, per year. The pregnant females form maternity colonies, and they find a hot, dark place to spend the maternity season. The Little Brown Bat babies are born in mid-June through early July.

The mother bats will nurse the babies while they are young. For the first month or so, the babies are unable to fly. The mother Little Brown Bats fly out each night and hunt for food, and then they return and feed the babies. By the end of August, the babies are able to fly, and they can go out with the mothers and hunt. During the maternity season, it is illegal to perform any kind of removal of Little Brown Bats from a home or building. Because the babies can’t fly, they are dependent upon their mothers for food. If exclusion devices are used to rid a home or building of adult bats, preventing them from returning, then the baby Little Brown Bats will starve. Bat removals can be performed when the maternity season is over.

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