Mexican free-tailed bat
Sixteen species of nocturnal, insectivorous bats can be found in the counties surrounding San Francisco Bay. Mexican free-tailed bats, also known as Brazilian free-tailed bats, are found throughout most of the southern United States. These are one of the most social of bat species. Colonies of more than one thousand to several million individuals are not uncommon. The largest colony (Bracken Cave, north of San Antonio, Texas) is estimated to have 20 million individuals!
Mexican free-tailed bats catch food on the wing. Their diet consists entirely of flying insects, mostly moths and mosquitoes. The colony at Bracken Cave can eat 250 tons of insects each night.
Bats and Rabies
Rabies is a viral infection of the central nervous system resulting in fatal inflammation of the brain. Bats, like all mammals, are susceptible to the rabies virus. Exposure to the virus is usually from a bite by an infected animal.
The frequency of infections in wild bats is relatively low. Only about one half of one percent of bats is known to be infected. However, a “grounded” bat, most frequently the condition of a bat encountered by people, is sick or injured and so has a higher likelihood of carrying the disease. Because bats can carry rabies, all staff who handle or work with bats are vaccinated against rabies.
Many individuals unnecessarily fear bats, but these fascinating creatures have an essential role in the environment we share with them; without bats and their voracious appetite for disease-carrying insects, people would be at greater risk from disease and agriculture would have many more pests to combat. A recent scientific paper on the economic value of bats to agriculture estimated that bats provided nontoxic pest-control services totaling $3.7 billion to $53 billion per year. This study did not even consider what the indirect costs of “replacing” bats with pesticides would be in terms of potential health and pollution threats from greater levels of toxins in the environment. (Center for Biological Diversity, http://www.biologicaldiversity.org/campaigns/bat_crisis_white-nose_syndrome/bats_economic_value.html.)
The bats at Lindsay Wildlife live in a specially designed, large Plexiglas enclosure. To take bats off-site for school programs and community events, we created unique travel enclosures. These, too, are made of Plexiglas and allow a safe, up-close encounter with a bat.
We currently house three Mexican free-tailed bats, all non-releasable because they cannot fly.
One of our female bats was found in Benicia with a shoulder injury and our male bat in Pittsburg with facial injuries. Both were brought and treated at Lindsay Wildlife Rehabilitation Hospital and because of their injuries, were determined that they could not be released back into the wild.