Bats’ reputations aren’t deserved
Nature: Bats’ reputations aren’t deserved
Published 5:30 am, Friday, May 22, 2009
Bats are among the most beneficial animals to humans and yet among the most feared.
The fear is because of the word rabies. But in the past 40 to 50 years, only about 40 people in the U.S. have died from probable bat-induced rabies. Far more people have died from lightning strikes, bee stings and even dog maulings than from rabid bats.
In fact, only one-half of 1 percent of bats carries rabies. Many other wild animals — particularly skunks, raccoons and coyotes — are more likely to carry rabies. Fortunately, the virus has been virtually eliminated from domestic dogs by aggressive pet vaccinations.
But back to bats. We have hundreds of millions of bats in the U.S., and the largest colony — more than 20 million Mexican free-tailed bats — breeds during the summer at Bracken Cave near San Antonio. Another 250,000 breed at Waugh Street Bridge over Buffalo Bayou in Houston.
So if rabies were common in bats, we’d have a huge outbreak of the virus in Texas. We don’t because rabies is exceedingly rare in bats. Moreover, a 2007 study by a group of European scientists discovered that when rabies hits a bat colony, the bats can produce antibodies to the virus resulting in immunity for up to 12 months. We need to learn how bats do it.
Despite superstitions about bats — they don’t get in your hair, they don’t suck your blood, they’re not blind — the nocturnal mammals are about the best critters humans could have around because they gobble up flying insects such as crop-destroying cutworm and corn borer moths as well as disease-carrying mosquitoes.
Bats emerge from daytime roosts just before or right after sunset and take flight in huge squadrons that look like smoke billowing up and across the sky. They are the only mammals that can fly. (Flying squirrels don’t fly, but rather glide from a higher to lower spot.)
Rather than flying on feathered wings like birds, bats fly by means of a flexible membrane stretching from their arm bones to their leg bones. They flap the membrane rapidly, and because it’s flexible, they can make rapid twists and turns in flight. But they cannot glide.
They detect insects with echolocation by emitting high-frequency sound from their mouths and noses.