|Eptesicus fuscus (Beauvois)|
Big Brown Bat
Don Linzey & Christy Brecht
Wytheville Community College
Wytheville, Virginia 24382
Last updated: 26 November, 2005
- Adult total length:
3 3/4 - 5 1/8 in. (94 - 130 mm)
1 3/8 - 2 1/8 in. (35 - 52 mm)
- Hind foot:
3/8 - 1/2 in. (10 - 11.5 mm)
6/10 - 7/10 oz. (14 - 21 g)
Bats are unique among mammals because their forelimbs are specialized for
true flight. Flight membranes, which are actually extensions of the skin
of the back and belly, connect the body with the wings, legs, and tail.
Unlike birds, bats use both legs and wings during flight. Other modifications
for flight include greatly elongated fingers to provide support for the
wing membrane, a keeled sternum for the attachment of the enlarged flight
muscles, and fusion of some vertebrae. The membrane extending from the tail
to the hind legs is known as the interfemoral membrane. The big brown bat
is one of the largest bats in the park. It has a wingspan of approximately
12 inches (305 mm). Along with its size, it can be distinquished from all
bats in the park by its long, uniformly dark brown fur. The fur of the
undersurface is paler. The blackish ears are short, broad, and rounded and
barely reach the nostrils when laid forward. The top of the blackish
interfemoral membrane is naked except for a sprinkling of hairs on the basal
left lateral view of
skull and mandible
dorsal view of skull
ventral view of skull
The big brown bat ranges from northern South America throughout Central America, Mexico,
and the United States into Canada.
All of the park's caves provide critically important habitats for bats. During the summer,
these bats are usually found in attics, barns, and bridges. During the coldest weather,
these bats move into caves and mines. Big brown bats usually hang alone while hibernating,
although small clusters of fewer than 20 bats also occur (Kurta, 1999).
The big brown bat mainly hibernates in buildings with only a few individuals overwintering
Great Smoky Mountains National Park:
The big brown bat has been recorded from ten localities within
the park ranging in elevation from 1,460 feet to 6,300 feet.
- Blount Co.:
Blowhole Cave; Saltpeter Cave; Gregory Cave.
- Cocke Co.:
Cosby Ranger Station (1,750 feet).
- Sevier Co.:
Park headquarters (1,460 feet); Greenbrier
(1,900 feet and 2,000 feet); LeConte Lodge
- Haywood Co.:
- Swain Co.:
Hazel Creek Ranger Station; Smokemont.
Maternity colonies of the big brown bat containing up to several
hundred individuals form during the summer (Harvey
et al., 1999). Females store sperm in their reproductive tracts
during the winter and ovulate in early spring, at the time of arousal
from hibernation. Following a gestation period of 60 days, breech
birth occurs. Eighty percent or more of females in eastern North
America produce twin pups, but litter size in the West is generally
one. Young are born weighing an average of 3.3 g and learn to fly at
18-35 days of age.
There are numerous records of these bats living 10 years or more.
The oldest recorded age for any big brown bat was at least 19 years
(Paradiso and Greenhall, 1967;
- Terrestrial Ecology
The senses of sight and hearing are well developed in bats.
Since most bats become active near dusk and are active much of the
night, sight is of little importance in navigation and in the
capture of prey. Instead, they use echolocation, a system somewhat
similar to radar. They emit ultrasonic calls far above the range of
human hearing that are reflected from objects ahead of them. They
hear the echoes and are able to avoid obstacles and find food in total
darkness. Different species can be distinguished by differences in the
structure of their echolocation calls (Fenton and Bell, 1981).
The large size and steady flight serve as good field identification
characteristics. During feeding maneuvers, the tail and wing membranes
are used to capture and restrain prey. Some insects are captured by the
tail membrane, which forms a pouch-like compartment. The bat must bend
its head forward in order to grasp the insect with its teeth and take
it into its mouth. Sometimes the bat may use its mouth to capture an
insect from its wing.
Eleven species of bats have been recorded in the park and all feed exclusively
on insects. During the colder months when flying insects are unavailable,
bats must either hibernate or migrate to warmer areas. Eight of our bats
are known to hibernate. Only three - the red bat, hoary bat, and the
silver-haired bat - are migratory. Bats have been seen flying over the
park during every month of the year. When flying during the winter, however,
they do not feed.
- Predators and Defense
No predators recorded from the park.
None recorded from the park.
- Transmittable Diseases
Bats are capable of transmitting two diseases to humans - rabies
and histoplasmosis. Histoplasmosis is a disease caused by inhaling
dust that contains contaminated spores. Tuttle (1988)
stated: "Less than a half of 1 percent of bats contract rabies, a frequency no
higher than that seen in many other animals. Like others, they die
quickly, but unlike even dogs and cats, rabid bats seldom become
aggressive." Bats do not attack when they get rabies; they just lie in
one place. Although it is rare for humans to contract rabies from
infected bats, persons handling them should be aware of this possibility.
Links to Other Sites
- Special Protection Status
- In Park:
All plants and animals are protected within
Great Smoky Mountains National Park.
Collection requires a permit which is usually
granted only for research or educational purposes.
- Map development
- Web page design & coding
- Denise Lim, University of Georgia, Athens
- John Pickering, University of Georgia, Athens
Barbour, R.W. and W. H. Davis. 1969.
Bats of America. Lexington: The University Press of Kentucky.
Fenton, M.B., and G.P. Bell. 1981.
Recognition of insectivorous bats by their
echolocation calls. Journal of Mammalogy 62 (2): 233-243.
Harvey, M.J., J.S. Altenbach, and T.L. Best. 1999.
Bats of the United States. Little Rock: Arkansas game and
Kunz, T. H. (ed). 1982.
Ecology of Bats. New York: Plenum Press.
Kurta, A. 1999.
Big brown bat. Pages 115-116. In: D. E. Wilson, and
S. Ruff (editors.). The Smithsonian Book of North
American Mammals. Washington, D.C.: Smithsonian
Kurta, T. H. and R. H. Baker. 1990.
Eptesicus fuscus. Mammalian Species No. 356: 1-10. American Society of Mammalogists.
Linzey, D. W. 1995a.
Mammals of Great Smoky Mountains National Park.
The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.
Linzey, D. W. 1995b.
Mammals of Great Smoky Mountains National Park-1995 Update.
Journal of the Elisha Mitchell Scientific Society 111(1):1-81.
Linzey, D. W. 1998.
The Mammals of Virginia. Blacksburg, Virginia:
The McDonald & Woodward Publishing Company, Inc
Paradiso, J. L., and A. M. Greenhall. 1967.
Longevity records for American bats. American Midland
Naturalist 78 (1): 251-252.
Tuttle, M.D. 1988.
America's Neighborhood Bats. Austin: University of Texas Press.
Last modified: 8 April, 2002