|Nycticeius humeralis (Rafinesque)|
Don Linzey & Christy Brecht
Wytheville Community College
Wytheville, Virginia 24382
Last updated: 26 November, 2005
- Adult total length:
3 1/8 - 3 3/4 in. (78 - 93 mm)
1 3/8 - 1 1/2 in. (35 - 37 mm)
- Hind foot:
1/4 - 3/8 in. (7 - 10 mm)
1/4 oz. (5 - 9 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. Evening bats are similar
to big brown bats, but smaller. They can be distinguished by their reddish
to dark brown fur above and tawny color below. The ears are blunt and rounded
and both the ears and membranes are black and generally naked, although in
some individuals hairs may be present on the extreme proximal portion of
the inter femoral membrane.
The evening bat occurs throughout much of the southeastern United States, extending
westward to southeastern Nebraska and northward to central Iowa and southern Michigan;
it is absent from the Allegheny Mountains.
left lateral view of
skull and mandible
dorsal view of skull
ventral view of skull
The evening bat usually inhabits tree cavities or buildings in summer. It almost never
enters caves. Winter habitat is almost completely unknown, but evening bats accumulate
large reserves of fat in autumn, sufficient for either hibernation or a long migration.
Great Smoky Mountains National Park:
This species was first recorded in the Park near Parson's Branch
by Dr. Michael Harvey during the summer of 1999. Two males were
recorded during the summer of 2000.
Mating probably occurs in late summer and early fall, with the sperm being
stored in the uterus of the female during the winter. Ovulation and
fertilization occur in the spring. Females give birth to 1 to 3 pups
(usually twins) during June.
The average life span in the wild is probably about two years, although
there are records of some individuals surviving for over five years
- 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).
Evening bats leave their roost near dusk. Individuals begin flying at a height of
12 to 23 m, but as darkness falls they come much lower to the ground. They have a
slow and steady flight. 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. 1999a.
Evening bat. Pages 117-118. In: D. E. Wilson, and S. Ruff (eds.).
The Smithsonian Book of North American Mammals. Washington,
D.C.: Smithsonian Institution Press.
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
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.
Watkins, L. C. 1972.
Nycticeius humeralis. Mammalian Species
No. 23: 1 - 4. American Society of Mammalogists.
Tuttle, M.D. 1988.
America's Neighborhood Bats. Austin: University of Texas Press.
Last modified: 8 April, 2002