Nature’s insect zappers now threatened by a new bug
Bats. Just the word makes some people cringe. Despite what movies, television and literature would have us believe, bats are not terrors of the night. One of the most misunderstood and maligned animals, they are incredibly important to our ecosystem and economy.
As primary predators of night-flying insects, bats help to control many of our most annoying pests. One bat eats as many as 3,000 flying insects a night during the summer months. Some bats consume such crop pests as cucumber beetles, June beetles, leafhoppers, cutworm moths and corn earworm moths.
There's no animal similar to a bat, our only flying mammal. The elongated fingers in a bat's hand are connected by skin to form a wing. Like all mammals, bats have hair and their young are born live and feed on milk.
Bats are not blind. Those that hunt in the dark have developed a system to help detect objects. These bats produce sounds at high frequencies, then listen to the echoes to discern objects. Using the reflected sounds, they form pictures in their brains just like we do by interpreting reflected light with our eyes. This is known as echolocation.
Bats are often associated with rabies. Like all mammals, they can contract the disease, but less than 1 percent of bats carry it. Bats with rabies are not very aggressive and die quickly.
Like most wild animals, bats will only try to bite when being handled. The infamous vampire bat of Mexico and South America is the only species to feed on blood, mainly that of cattle or other domestic animals.
While tropical bats are active year-round, those in temperate regions either migrate or hibernate in the winter. Many bats hibernate in caves in winter and move to trees and buildings in the summer. Some bats reside in caves all year but have different summer and winter roosts.
During hibernation, a bat's metabolism slows so that it uses very little of its stored fat. Heart rates fall drastically and body temperatures drop to 40-60 Fahrenheit. To control body temperature, bats often roost together in great numbers.
Disturbance by people is a major cause of the decline of many bat species. Disturbing a maternity colony can cause mothers to drop their young or move them to a less suitable site. Waking bats during hibernation causes them to burn precious fat reserves they have stored for the winter.
Bats are also threatened by the loss of feeding or roosting habitat, usually wooded areas near water sources. As traditional roosts in trees and caves have been destroyed, many bats seek shelter in man-made structures.
Scientists have studied the roosting requirements of bats to create artificial homes. Some bats use these bat houses and condos quite successfully.
Two endangered bat species live in the Chesapeake Bay watershed: Indiana bats and Virginia big-eared bats.
Indiana bats roost under tree bark along wooded streams in the summer. During the winter, they hibernate in caves in dense clusters, averaging 300 bats per square foot. Females usually bear only one young in June.
The Virginia big-eared bat, another endangered species, occupies caves in both the summer and winter. They, too, bear only one pup each year.
Protecting habitat is crucial to saving these species. Wooded streamside areas need to be protected for roosting.
It is also critical that people are prevented from entering maternity caves and winter hibernation caves. Because bats use these caves seasonally, entry may only have to be restricted during certain months. A cave entrance can be gated or fenced, preventing people from entering yet allowing bats to fly in and out.
Recently, a new threat has emerged: white-nose syndrome. Thousands of hibernating bats died this winter in the Northeast. In and around caves and mines in eastern and upstate New York, Vermont, western Massachusetts and northwestern Connecticut, biologists found sick, dying and dead bats in unprecedented numbers. These bats often have a white fungus on their muzzles and other parts of their bodies.
Affected dead and dying bats are generally emaciated, and those found outside are often severely dehydrated. The cause of these deaths is a mystery.
Biologists are not certain whether the bats are transmitting the disease among themselves; people are spreading it; or both bats and people are involved.
Because females produce just one pup a year, these deaths could create a crisis in bat populations in those states.
The bat conservation community is researching this disease as well as raising money to fund the research.
National and regional caving organizations are coordinating with state biologists to provide the most current information to their constituents regarding advisories. They are also documenting cave visitations to determine if cavers could be spreading the white-nose syndrome.
For information about white-nose syndrome, visit the U.S. Fish and Wildlife Service Northeast Region's website at www.fws.gov/northeast/white_nose.html.
Members of the public should report occurrences of white-nose syndrome to their state wildlife agency or local U.S. Fish and Wildlife Service office or email WhiteNoseBats@fws.gov
For information about bats, bat houses and how to protect these animals, contact Bat Conservation International, www.batcon.org, P.O. Box 162603, Austin, Texas, 78716; or 800-538-2287.
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