Just the word makes some people cringe. However, bats are probably the most misunderstood animals. Despite what movies, television and literature would have you believe, bats don’t terrorize the night.
Bats are incredibly important not only to our natural world but to our economy. As primary predators of night-flying insects, bats help to control many of our most annoying pests. A single little brown bat can catch 1,200 mosquito-sized insects in an hour. Big brown bats consume costly crop pests including cucumber beetles, June beetles, leafhoppers, cutworm moths and corn earworm moths.
Little Brown Bat. Don Pfritzer photo
Virginia Big-eared Bats, USFWS photo
While tropical bats are active year-round, those in temperate regions either hibernate or migrate during the winter. Many bats hibernate in caves in winter and move to trees and buildings during 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 slow drastically and body temperatures drop to 40 to 60 Fahrenheit. To control body temperature, bats often roost together in great numbers.
What’s Happening to Bats?
Disturbance by people is a major cause of decline in many bat populations. They are also threatened by loss of feeding or roosting habitat, usually wooded areas near water sources. Disturbing a maternity colony can cause mothers to drop their young or move them to a less suitable site. Disturbance during hibernation wakes bats, causing them to burn the precious fat reserves they have stored for the winter. Even responsible cave explorers can inadvertently disturb bats at critical times of the year.
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 in order to provide artificial homes. Some bats use these bat houses quite successfully.
Bats in the Chesapeake Bay Watershed
Two endangered species of bats live in the Chesapeake Bay watershed, Indiana bats and Virginia big-eared bats. During summer, Indiana bats roost under tree bark along wooded streams. During the winter, Indiana bats hibernate in caves in dense clusters, averaging 300 bats per square foot. Because they mass together in winter, disturbance to one wintering cave can lead to high fatalities.
The Virginia big-eared bat, another endangered species, occupies caves during both the summer and winter. They too and suffer many of the same threats as Indiana bats.
Protecting habitat is crucial to saving these species. Wooded streamside areas need to be protected for roosting. Preventing people from entering maternity caves and winter hibernation caves is critical. Since bats use these caves seasonally, entry may only have to be restricted during certain months. Cave entrances can be gated or fenced, preventing people from entering while allowing bats to fly in and out.
For more information :
U.S. Fish & Wildlife Service Endangered Bats
Bat Conservation International