There are about 5,500 species of mammals on the planet. Most live on land, some live underground, some live in trees, some live in oceans but only one mammal can fly – a bat.
Worldwide there are 1,400 species of bats. Forty-five of those species can be found in North America, 25 in California and 18 call the San Luis National Wildlife Refuge Complex home for at least part of the year.
Like many bird species, many bats are migratory – moving back and forth between their winter non-breeding grounds, and their summer breeding grounds. There is evidence, however, that a non-migratory population of Mexican freetail bats may be permanent residents of the San Luis refuge.
Also like their avian neighbors, bats have distinct calls which biologists use to help identify the animals by species. The Passive Acoustic Bat Monitoring program at the San Luis Complex has been instrumental in helping refuge biologists identify specific species of bats on the refuges. Bat activity on the refuge is greatest from February through October.
Mexican freetail bats are the most identified species on the refuge. That species is known as the jet of the bat world because of its speed in flight and maneuverability in the air while pursuing flying insects. The Western red bat on the refuge is unique because it roosts only in broad leafed trees, like willows, in riparian areas.
Like snakes, spiders and things that go bump in the night, bats are feared by many people. Perhaps that is because the animals only come out after dark and are hard to see. It might be folklore about bats getting stuck in women’s hair or stories about them turning into vampires and seeking human blood that makes people quake at the sight of the little mammals.
There are three species of blood-drinking vampire bats but none of them live nearby (nor in a Transylvanian castle). All 18 local species are insect eaters, and they are voracious. Because they choose to dine on six-legged flyers, large flights of bats are usually found near bodies of water or over wetlands where their food source is most plentiful. Some bats are known to eat as many as 600 mosquitoes an hour.
According to the U.S. Department of Agriculture, bats are our most important predators of night-flying insects. Besides eating mosquitoes, bats consume moths, beetles, crickets and other insects that pose serious threats to crops or spread diseases to humans or their livestock. Bats are an ecologically safe and cheap method of pest control.
There are other important things to know about bats. Batman is fictional and bats don’t ride in Batmobiles. Batting an idea around probably has nothing to do with mammalian biology. Baseball bats are real but they don’t eat insects they create them, to wit: the infield fly.
The Merced National Wildlife Refuge which is located at 7430 West Sandy Mush Road, the San Luis National Wildlife Refuge and the San Joaquin River National Wildlife Refuge comprise the San Luis National Wildlife Refuge Complex. Its headquarters and visitor center are located just north of Los Banos off Highway 165 at 7376 South Wolfsen Road.
The refuges are open to visitors daily from one half-hour before sunrise to one half-hour after sunset. The visitor center is open Monday through Friday except federal holidays from 8 a.m. to 4:30 p.m. For more information, call the refuge visitor center at 209-826-3508, ext. 127 or check out the upcoming events on the website at fws.gov/refuge/san-luis.
