Natural History

The big brown bat is one of the most misunderstood bats.The big brown bat eats enormous amounts of harmful insects like mosquitoes. They are really shy and not that aggressive. Most brown bats like the big brown bat are known to carry rabies, but the incidence of this disease in bats is very low. There is a much better chance of animals like raccoons, foxes, skunks, or even house pets like cats or dogs to get sick with rabies.

Many bats all around the world are in danger of extinction because of loss of shelter and bat habitats. The big brown bat is legally protected and cannot be hurt or killed without a special permit. Many people are now learning about the good things to know about this shy, shy mammal .

Habitat

Big brown bats spend most of the daytime asleep in dark places like hollow trees or caves. The big brown bats roost in man-made things like barns, old buildings, and under window shutters mostly during the summer months. Some of the big brown bat’s threats are barn owls, horned owls, and black snakes.

Like a lot of the bats today , the big brown bat is nocturnal, which means it is active right before dark and all through the night. Bats fly through the night sky using echolocation. Bats can’t see well so they send out ultrasonic sounds through their mouths or nose that are bounced off objects in the bat's path . The big brown bat uses its echolocation to find food and to find its way around at night.

The big brown bat hibernates during the winter months, most of the time in different places from where they did their summer roosts. Some winter roosts are in caves and underground mines where temperatures stay the same all year. Scientists are still not sure, however, where a large group of big brown bats spend the winter. Mating time for the big brown bats comes in November through March. After mating season, pregnant females divide up into maternity colonies. The big brown bat gives birth in late May and early June. The big brown bat is called one of the “ long -lived bats” because it lives longer than most bats and birds. The normal life span for a big brown bat is 18-20 years.

Present Status

Species of Concern in Maine 

Physical Description

The big brown bat is pretty big in size. It is 4 to 5 inches in length and weighs 1/2 to 5/8 of an ounce.

The fur on the big brown bat is mostly long and shiny brown. The body is brown on its back and lighter on its belly. The wings, ears, feet, and face are dark brown to blackish colored and bare of hair. There are seven other kinds of bats that look a lot like the big brown bat in appearance, but which are a lot smaller in size.

The big brown bat uses its wings to wrap up in when it sleeps to keep warm or when it makes its “night roost.” A night roost is when the bat roosts itself upside down to let its food digest.

Diet

The big brown bat is a carnivore and eats only bugs. Some of the bugs it eats are beetles, stone flies, cockroaches, moths, wasps, flying ants, and dragon flies. The big brown bat usually feeds the most in the warmer months . They have to accumulate enough fat in the warmer months to last them through the winter . Sometimes they can gain up to a 1/3 of their weight in the warmer months.

A newborn baby bat can eat up to 1.4 grams of insects per hour. The average bat can eat up to 2.7 grams per hour. The big brown bat does not feed when it is raining or when it is below 10 degrees. After they eat they do something called a “night roost,” which means they find a safe cool place and hang themselves upside down for the night and let their food digest.

Causes of Animal's Present status

Some of the reasons the big brown bat is a species of concern is because of the loss of habitat. Places for bats to live are becoming one of their top problems because the places they are living are getting rebuilt and cut down. The big brown bat likes to live in old run down buildings and in people’s homes. Now that people are making new buildings out of old, the bats are getting run out of their homes.

Food is also one of the many reasons the big brown bat species is becoming so low. The big brown bat feeds in the warmer months so when winter comes around they have less food and fewer places to live. When this happens, they try to find other places to live that are not their habitat.

When the big brown bat has its babies in places where humans live or are building, they often have the bat babies taken away and most do not live.

Bibliography

Big Brown Bats. March 3, 2002. http://wildwnc.org/af/brownbat.html. (March 19, 2003.)

Eptesicus fusses. Feb. 8, 2002. http://www.batcon.org/discover/species/efuscus.html.
(Feb. 28, 2003.)