California
Eptesicus fuscus   1-U.S. Geological Survey; 2-Ronald Gonzales, California Department of Fish and Game | |
| Type of Animal: | Mammals |
|---|---|
| Class: | Mammalia |
| Order: | Chiroptera |
| Family: | Vespertilionidae |
| Federal Status: | |
| State Status: | |
| Occurrence: | |
| Habitat: | Caves,Farmland,Urban,Forest |
| Description: | Bats are the only true flying mammals, and they occur in almost all areas around the world. There are 1000 species of bats, 46 of which occur in the United States. Bats make up 25% of all mammals. Unfortunately there are many myths about bats. They are not blind and do not become entangled in human hair. Some bats may carry rabies, but not all. In fact, less than 1% of the population carries rabies. The best way to avoid contracting rabies from them is to not handle them. Bats typically only bite in self-defense and will leave humans alone unless provoked. Like all bats, big brown bats are a very important component of our ecosystem. Bats are nocturnal and begin flying soon after sunset. During this time they forage for flying insects such as moths, beetles, flying ants, and mosquitoes. During the winter and on rainy or cold evenings, this species does not feed and instead depends on fat reserves to survive. They depend on echolocation to locate their prey. The bats emit short, high-pitched sounds that echo. By listening to the echo they are able to figure out where obstacles are located, even obstacles as thin as a piece of thread! Bats are natural predators of the insects that are considered to be agricultural pests. Without bats, farmers would be forced to increase their use of chemical pesticides, which could increase the price of our produce and cause negative effects on other wildlife that live in and around agricultural areas. In desert habitats, bats are the primary pollinators of giant cacti. Big brown bats are one the most commonly seen bat species throughout California, especially in urban areas. Most bats are seen in colonies of 100 or more, but these bats may also live alone or in small groups. During the spring and summer months, male big brown bats are solitary and females form maternity colonies of up to 75 individuals. The maternity colonies are often found in snags, barns, and caves. The females usually return to the same maternity site every spring. In California, female big brown bats usually give birth to one young between May and July. The pups learn to fly by the age of 35 days, and by September the adults and young leave the maternity colony in search of wintering quarters. The bat population is in steady decline due to numerous factors. The main reason for the decline is human interference, such as habitat destruction and alteration. Bats live in natural structures like caves, but they also live in manmade structures such as bridges and abandoned mines. Vandalism in these areas drives the bats away and kills many of them. Activities such as building bonfires under bridges can also cause them to die from smoke inhalation. Many bridges and mines also contain maternity dens, so these detrimental activities not only kill the adults but the new generations as well. You can help protect bat populations by avoiding areas that may contain bats. If you must enter a bat roost area, be careful to leave the area as you found it. The big brown bat is one of the most common bats found in homes. Unfortunately, many homeowners kill the bats. A kinder solution, however, is to wait for the bats to leave in the evening to forage and block off the entrance. The best time of year to do this is either late in the year or early in the year. Blocking entrance holes during the spring, summer, and fall may trap pups that are too young to fly. |
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| References: | Jameson et al. 1988. California Mammals. Wilson et al. (editors). 1999. The Smithsonian Book of North American Mammals. Whitaker (editor). 1998. National Audubon Society Field Guide to North American Mammals, Revised Edition. Zeiner et al. (editors). 1990. California’s Wildlife, Volume III, Mammals. |
| Other Sites: | |
| Field Office(s): | Bakersfield; Barstow; Eagle Lake; Mother Lode; Palm Springs; Redding; Ridgecrest; Ukiah |