All About the Little Brown Bat

Found across Canada and the US, the little brown bat is a species of bat known for its close association with humans.


Little brown bats can be brown, gold, or yellow in color. The critters typically weigh between seven to fourteen grams. The wingspan of the average little brown bat is between 22 to 27 centimeters. Like other bats, the wings of these critters are made out of a thin membrane that is stretched over their bones.


In the US, the critters are widely found in northern states. Little brown bats are found in small numbers in the southern US states. In Mexico, the critters inhabit high-elevation forests. In Canada, little brown bats are widely distributed. The critters are found in all of the Canadian provinces and territories except Nunavut. Little brown bats are the most widely distributed bats in Canada.


Although the critters are not territorial, they live communally in colonies. A colony of little brown bats can have thousands of the critters. Typically, they do not migrate to very far distances during winter. Little brown bats in Canada, for example, do not migrate out of Canada.


Little brown bats feed on flying insects. Although the critters constitute nuisance wildlife, their presence around homes can be beneficial in terms of insect control. It has been estimated that the critters can feed on 1,000 insects within an hour. They feed on adult insects as well as larval insects. Some of the insects they feed on are mosquitoes, beetles, mayflies, and moths. Because insects make up the diet of the critters, insecticides can be used to control their population. 

little brown bats

Insecticides reduce the population of insects, the food of the bats, and discourage the activity of the bats. It is worth noting that insecticides are also poisonous to the critters. The bats identify their prey through echolocation. They send out a sound that bounces back based on the nature of the environment. Based on the sound of the echo which they get as feedback, the critters evaluate the size and location of the prey.
As nocturnal animals, little brown bats are most active at night. They start their hunting just after dusk. In one night, the critters can consume up to half their weight in insects. The new mothers consume much more food. They can eat more than their weight in insects in one night.

Life cycle

Little brown bats become sexually mature from when they are about a year old. Both the males and females can mate with different partners. The mating activity of the critters is usually highest during the fall when they swarm. The critters are especially known for their promiscuous mating habits. The female bats usually store the sperm till much later when they ovulate for fertilization to occur. Typically, fertilization occurs after ovulation during the spring. Little brown bats have a gestation period of 50 to 60 days. The actual length of the gestation period is dependent on factors such as the age and health condition of the female bat. The young bats are usually born in June or July. At birth and shortly after, the pups are heavily dependent on their mothers. The pups typically feed on insects as well as their mother’s milk. Young little brown bats can fly after about 3 weeks. After the pups are weaned off milk, they prepare for fall, accumulating fat during the period. The average lifespan of the critters is 6 to 7 years. However, there have been cases of bats living for much longer, up to 30 years.


Little brown bats are not exactly blind. These critters have excellent vision which they apply in addition to echolocation. They especially apply their vision when they migrate long distances. The critters are hibernators, and they leave their summer roosts for winter roosts during the winter. The winter roosts, which are known as hibernacula, could be abandoned mines or caves. Usually, the critters make hibernacula out of places that are humid and with good temperatures. The summer roosts, on the other hand, are dark and warm, places such as tree cavities. The summer roosts of the critters are otherwise known as maternity roosts. Little brown bats can travel for distances up to 1,000 km from their summer roosts to their winter roosts.
During winter, little brown bats hibernate completely, slowing their heart rate to about 20 beats per minute. They survive on fat stores during this period. The predators of the critters include raccoons, snakes, and hawks. When looking for suitable roosts, little brown bats typically consider accessibility to predators and security. It is noteworthy that the population of the bats has been on a steady decline. The critters are often killed by diseases.