Aerial mammals are perched on the state’s conservation radar
By Bob Conrad
This article originally appeared in RLIFE Magazine, November 2006.
It’s furry, hungry and the victim of stereotypes. The Brazilian free-tailed bat, Tadarida brasiliensis, is one of Nevada’s 23 bat species and has a part-time home in the Truckee Meadows. The small, flying mammal plays an important ecological role, one that has the interest of wildlife biologists and conservationists who are trying to spread the word about one of the state’s most misunderstood creatures.
The Brazilian free-tailed bat lives for about half the year, from June through September, in the East McCarran Boulevard bridge. More than 80,000 roost in the bridge’s concrete crevices above the Truckee River. By October, the bat has left northern Nevada to spend the winter in warmer climates.
“The Brazilian free-tailed bats may migrate as far south as Mexico or as close as Sacramento for the winter,” says Jennifer Newmark, biologist with the Nevada Natural Heritage Program, a division within the Nevada Department of Conservation and Natural Resources. The Natural Heritage Program maintains data on Nevada’s plants and animals at risk of becoming threatened or endangered.
Newmark, a bat expert, helps lead the Nevada Bat Working Group, a group that supports conservation and management efforts for Nevada bats. The group recently revised the state’s bat conservation plan, a document that offers maps, habitat information, conservation goals and the state’s bat history.
Bats are native to the state, Newmark says. The 1858 mining boom left a legacy of abandoned mines which provide the potential for bat habitats. Typical roosting sites for Nevada’s night creatures are the state’s many abandoned mines, natural caves and trees.
The 1946 publication of “Mammals of Nevada,” by biologist Raymond Hall, said that the state’s bat populations are constrained by naturally low birth rates—female bats generally give birth to about one new pup a year. Adding to their minimal rate of reproduction, habitat threats are common, Newmark says. Mine closures for example can threaten habitats because bat species tend to live in large groups. The loss of a single roosting site, such as an abandoned mine or a natural cave, could have a significant effect on a particular bat species.
It’s only recently that wildlife managers started to actively conserve bats, and in 2004 protection for eight species of Nevada’s bats was added to the Nevada administrative code, making nine out of the state’s 23 species protected. Newmark says that public misunderstanding of bats is another concern facing bats. Rabies, which is commonly associated with bats, contributes to misperceptions.
“It is estimated that less than one percent of all bats get infected by the rabies virus, and contracting rabies from bats is easily avoided by not handling or touching bats,” Newmark says. “When bats become infected with the rabies virus, they typically become paralyzed and passive. That’s why you see them on the ground.”
Bats rarely become aggressive but will bite in self defense if handled. Newmark cautions that “any mammal can contract the rabies virus. Any animal bite, even if it’s not a bat, should be reported immediately even if no symptoms are present, so that life saving, post-exposure treatment can be administered.”
Despite misconceptions, Newmark says that bats are highly beneficial for a number of reasons. Bat vocal sounds, which are undetectable to humans, have been researched to create aids for the blind. And the amount of insects they eat is a significant benefit to the Truckee Meadows. A nursing female bat can consume its body weight in insects each night and “it’s estimated that the 80,000 bats roosting under the McCarran bridge eat up to 75 metric tons of insects each summer,” Newmark says. “To help put that in perspective, that’s equivalent to about 55,000 large pizzas.”
Roosting in the McCarran bridge gives the Brazilian free-tails ample food in the summer—mosquitoes near the river and potential pests near agricultural lands. “Without the benefit of insect-eating bats, farmers would have to apply more pesticides to protect their crops and more insecticides would need to be used to protect the public from disease-carrying mosquitoes,” according to the Nevada Department of Wildlife.
On a global scale, the non-profit Bat Conservation International documented more than 450 commercial products in the tropics that come from plants that depend on bats for pollination or seed dispersal. Bat guano is used for fertilizer and in antibiotics. Here at home, bats are often seen in the summer flying above Reno’s skies hunting for insects that circle casino lights, but the best bat show takes place at the East McCarran bridge.
“People can watch the bats leave the bridge each night to forage just after sundown,” Newmark says.
For information on Nevada’s bats, visit the Western Bat Working Group online.