MOUSE-TAILED BATS: Rhinopomatidae

PHYSICAL CHARACTERISTICS

Also known as long-tailed bats, the bats in this family have a tail almost as long as their head and body. This slender, long tail is unique among all the bats. These bats are small to medium-sized, about 2 to 3.5 inches (5 to 9 centimeters), not including the tail. Their backs are generally gray-brown to dark brown, and they may be lighter on their underside.

The ears of mouse-tailed bats are rather large and connected by a band of skin across the forehead. The ears extend past the nose when they are laid forward. Their snouts have a small, rounded noseleaf, a horseshoe-shaped flap of skin around the nose.

GEOGRAPHIC RANGE

Mouse-tailed bats are generally found in Africa and Asia, across the Sahara, from western Africa through the Middle East to India and Thailand.

HABITAT

Mouse-tailed bats are usually found in arid, extremely dry, regions. This can range from deserts to extremely dry woodland. They roost, rest or settle, in caves, rock clefts, wells, pyramids, and buildings.

DIET

Mouse-tailed bats eat insects, including flying ants, termites, beetles, and moths.

As the months turn cooler the bat begins store fat, especially in the abdominal, stomach, region. These fat deposits can equal the bat's normal body weight. During the winter months when insects are in short supply some species of mouse-tailed bats go into a type of deep sleep called torpor, and they absorb the fat deposits. During this period the bat is able to survive for several weeks without food and water. In some areas, some species migrate between summer and winter roosts.

BEHAVIOR AND REPRODUCTION

When mouse-tailed bats roost they often hang by the thumbs as well as the feet. They emerge from their roosts at dark and begin their search for food. The small mouse-tailed bat has an unusual flight in that it rises and falls, much like some small birds. This species travels by a series of glides, some of great length, and occasionally it flutters, about 20 to 30 feet (6 to 9 meters) above the ground.

Like all bats, mouse-tailed bats are nocturnal, active at night. They use echolocation (eck-oh-loh-KAY-shun) to pinpoint, identify, and capture their prey, the animals they hunt for food. In echolocation, the bats call out a high-frequency sound in the ultrasonic ranges, which is above the sounds humans can hear. These sound waves bounce off of objects and echoes or bounces back to the bat. The bat can then determines the location, size, distance, and speed of the object.

Mouse-tailed bats generally hunt in the open air high above ground. With small prey distributed throughout a large space, the bats must cover a large search area to find an insect. Mouse-tailed bats can travel up to 12 miles (20 kilometers) from their roost sites in a single night.

Female bats give birth to one young annually. The young are fully grown and weaned in about six weeks. Reproduction periods of these bats depends upon where they live and their species.

TUNING TO BATS

Bats are difficult to study because they fly and are only active at night. Radio tagging, the marking of bats with a radio transmitter, is one technology that researchers are using to study bats. Transmitters are typically 5 percent of the bat's body weight and can be glued to the bat's back or put on a collar. Results from these studies show that long-tailed bats are highly selective in choosing nest sites and sites are usually used for only one day.

MOUSE-TAILED BATS AND PEOPLE

Mouse-tailed bats are indirectly helpful to humans because they eat many insects that humans consider pests.

CONSERVATION STATUS

One species, MacInnes' mouse-tailed bat, is categorized as Vulnerable, facing a high risk of extinction in the wild due to the destruction the bat's natural habitat. The other three species are not listed as threatened with extinction.

HARDWICKE'S LESSER MOUSE-TAILED BAT (Rhinopoma hardwickei): SPECIES ACCOUNT

Physical characteristics: Hardwicke's lesser mouse-tailed bats are also called long-tailed bats, referring to their long, thin mouse-like tail. The tail can be as long to the length of the head and body combined.

These bats are relatively smaller than other species in the family. They have a body length of about 2.5 inches (5.5 centimeters), and their forearms range in length from 2 to 2.5 inches (5.2 to 6.4 centimeters). They weigh about 0.4 to 0.5 ounces (11 to 14 grams).

The fur of lesser mouse-tailed bats is soft. It is generally a gray-brown color on the upper side of and a paler color of the same shade on its underside. These bats appear to be furless on their faces and backsides. These bats feature large ears that are connected by a band of skin across the forehead. The snout has a small, rounded noseleaf. Directly above the nostrils are slits that they can open and close.

Geographic range: Lesser mouse-tailed bats extend from northern Africa to southern Asia. They are found in Morocco, Senegal, Egypt, Israel, Syria, Jordan, Lebanon, Saudi Arabia, Yemen, Afghanistan, India, Socotra Island, and Pakistan.

Habitat: Lesser mouse-tailed bats typically live in extremely dry or arid regions, They are found in mostly treeless areas ranging from deserts to grasslands and dry woodland.

Diet: Lesser mouse-tailed bats feed on flying insects, such as moths and beetles. These bats build up a large fat reserve in their lower abdomen and can go without feeding for two months.

Behavior and reproduction: Lesser mouse-tailed bats have unique adaptations, changes in body structures and functions, for life in dry regions. They can close valves in the nostrils to keep from breathing in dust. They can also control their kidneys to reduce water loss. In extremely hot weather these bats move into a shelter.

Lesser mouse-tailed bats find their food using echolocation. Studies have found that when several of these bats forage for food together, each uses an echolocation call of a different sound frequency.

Lesser mouse-tailed bats roost in caves, rock clefts, wells, pyramids, palaces, and houses. They gather in both large and small colonies. Colonies can number in the thousands, or range from one to ten individuals. They often hang by their thumbs as well as feet. Studies have found that roosting sites are generally used for only one day, and then they will select another site.

Studies indicate that lesser mouse-tailed bats are polygamous (puh-LIH-guh-mus), having more than one mate. Female lesser mouse-tailed bats produce one offspring annually. They gestate, are pregnant, for a period of 90 to 100 days. In a field study of lesser mouse-tailed bats, birth occurred over ten days in mid-December. The young began flying at five to six weeks.

Lesser mouse-tailed bats and people: Lesser mouse-tailed bats eat insects that many humans consider pests. There are indications that these bats may be declining in population, due to human activities. Reasons for the population decline include clearing these bats' forest habitats, disturbing their roosting sites, and introducing animals into an area that are predators of these bats, animals that hunt them for food.

Conservation status: Lesser mouse-tailed bats are not currently in danger of extinction. There is some evidence that long-tailed bats are now rare or absent at many sites where formerly they were common. ∎

FOR MORE INFORMATION

Books:

Fenton, Brock M. Bats. New York: Checkmark Press, 2001.

Fenton, Brock M. The Bat: Wings in the Night Sky. Buffalo, NY: Firefly Books, 1998.

Richardson, Phil. Bats. London: Whittet Books, 1985.

Ruff, Sue, and Don E. Wilson. Bats. New York: Benchmark Books, 2001.

Schober, Wilfried, and Eckard Grimmberger. The Bats of Europe and North America. Neptune City, NJ: T.F.H. Publications, Inc., 1997.

Periodicals:

Schnitzler, Hans-Ulrich and Elisabeth K.V. Kalko. "Echolocation by Insect-Eating Bats." BioScience (July, 2001): 557–569.

Web sites:

"Bat Information." The Bat Conservation Trust. http://www.bats.org.uk/bat_info.htm (accessed on July 2, 2004).

Hester, L., and P. Myers. "Rhinopomatidae." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Rhinopomatidae.html (accessed on July 2, 2004).

Simmons, Nancy B. and Tenley Conway. "Rhinopomatoidea." Tree of Life Web Project. http://tolweb.org/tree?group=Rhinopomatoidea&contgroup=Microchiroptera (accessed on July 2, 2004).