The Tri-colored bat is one of the smallest of the park's bats, and is fairly common. During the summer, these bats roost mostly in trees. Hibernation sites include caves, abandoned mines, and rock crevices with eastern pipistrelles usually hanging singly in warmer parts of the cave (Harvey et al., 1999). Blowhole Cave contains one of the largest known winter colonies of the Tri-colored bat in the United States.

Species Measurements:
- Adult Total Length: 75-95 mm (3-3 3/4 in.)
- Tail: 32-46 mm (1 1/4-1 7/8 in.)
- Hind Foot: 7-9 mm ( 1/4-3/8 in.)
- Weight: 3-6 g (1/10-1/5 oz.)

- Physical Characteristics:
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 Tri-colored bat is one of the smallest of the park's bats and is fairly common. Adults are light reddish-brown above and slightly paler below. The dorsal hairs are tricolored, being darkest at their base, yellowish-brown in the middle, and dark at the tip. Long guard hairs are completely reddish-brown. The skin covering the forearms is reddish, and serves as a distinctive identification characteristic. The ears are longer than broad, and taper to a narrowly rounded tip. When laid forward, the ear reaches slightly beyond the tip of the nostrils. The dorsal third of the interfemoral membrane (uropatagium) is lightly furred.

Habitat:
All of the park's caves provide critically important habitats for bats. During the summer, these bats roost mostly in trees. Hibernation sites include caves, abandoned mines, and rock crevices, with eastern pipistrelles usually hanging singly in warmer parts of the cave (Harvey et al., 1999). A bat may shift from one spot to another in the cave during the winter. Blowhole Cave contains one of the largest known winter colonies of the eastern pipistrelle in the United States. Rabinowitz (1979) reported that eastern pipistrelles selected hibernating roosts in relatively remote areas of Park caves containing little or no air flow. Over 80% of the bats in these areas hibernated in places where the ambient temperature was 8-11? C. Most bats avoided both highest and lowest temperature extremes.

Reproduction:
Mating occurs during autumn. 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, twin pups are born during June. Each weighs about 20% of its mother's weight. Tri-colored bat pups grow rapidly, and begin to fly between the ages of 14-21 days. Young Tri-colored bats are weaned at 4 weeks of age.

Longevity:
The oldest recorded age for any Tri-colored bat is 14.8 years (Walley and Jarvis, 1971).

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).

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 the species found in the park are known to hibernate. Only three - the red bat, hoary bat, and the silver-haired bat - are migratory. Bats are seen flying over the park during every month of the year. However, when flying during the winter, they do not feed.

Predators and Defense:
No predators recorded from the park.

Parasites:
None recorded from the park.

The eastern pipistrelle ranges throughout the eastern United States west to central Minnesota, western Oklahoma, and central Texas. The range extends south through eastern Mexico to Guatemala and Belize.

Eastern pipistrelles have been recorded in the park and along the Foothills Parkway at elevations ranging from 1,530 feet to 2,700 feet.

References:

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.

Fujita, M.S. and T.H. Kunz. 1984. Pipistrellus subflavus. Mammalian Species No. 228: 1-6. American Society of Mammalogists.

Harvey, M.J., J.S. Altenbach, and T.L. Best. 1999. Bats of the United States. Little Rock: Arkansas Game and Fish Commission.

Kunz, T.H. 1999. Eastern Pipistrelle. Pages 114-115. In: D.E. Wilson, and S. Ruff (eds.). The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.

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

Rabinowitz, A.R., and B. Nottingham. 1979. Human Visitation and Fall-Winter Cave Usage by Bats in Great Smoky Mountains National Park. National Park Service. Final rep. on contract #PX-5000-90281.

Tuttle, M.D. 1988. America's Neighborhood Bats. Austin: University of Texas Press.

Walley, H.D., and W.L. Jarvis. 1971. Longevity Record for Pipistrellus subflavus. Transactions of the Illinois Academy of Science 64(3): 305.