OLD WORLD LEAF-NOSED BATS: Hipposideridae

PHYSICAL CHARACTERISTICS

Also called roundleaf bats, Old World leaf-nosed bats vary greatly in size. They have a combined head and body length that ranges from 1.1 to 4.3 inches (2.8 to 11 centimeters). One species, Commerson's leaf-nosed bat, is one of the largest insect-eating bats of all the microchiroptera (my-kro-keer-OPter-ah; one of two bat categories that includes most of the bats in the world), with a wingspan of about 2 feet (0.6 meters). These bats are closely related to and share many of the features of horseshoe bats. They have a fleshy fold of skin around their nostrils called a noseleaf, which is leaf-like in appearance. The lower part of the noseleaf is shaped like a horseshoe or U-shape, with leaf-like flaps of skin above that protrude outwards.

The ears of these bats vary in size. They do not have a tragus (TRAY-gus), a flap of skin in front of the ear opening, which is common in many bats. These bats have only two bones in each toe. Their tail length ranges from nothing to approximately 2.4 inches (6 centimeters). Fur color ranges widely among the species, from reddish and yellowish to brown and cream. In several species, males and females have different fur colors, as well as different body and noseleaf sizes.

GEOGRAPHIC RANGE

Old World leaf-nosed bats are found in tropical (hot and humid weather) and subtropical areas of the Old World, meaning the part of the world made up of Australia, Africa, Asia, and Europe. They are found in Africa and southern Asia, east to the Philippine Islands, the Solomon Islands, and Australia.

HABITAT

These bats live in a range of habitats that include deserts and rainforests. They roost (settle or rest) in caves, underground openings, buildings, and hollow trees. One species, the fulvous (FUL-vus) leaf-nosed bat, has been found in burrows of a large porcupine in Africa.

DIET

Old World leaf-nosed bats eat insects, although little is known about the specific insects that make up their diet.

BEHAVIOR AND REPRODUCTION

There is little information on the behavior and reproduction habits of many Old World leaf-nosed bat species. Most roost in groups that range widely in size: from about twelve to groups of hundreds, to approximately 5,000. Some species appear to roost singly. The primary roosting sites of these bats are caves and tunnels, yet many roost in tree hollows and buildings.

Old World leaf-nosed bats are nocturnal, or active at night, as are all bats. When they emerge from their roosts at night, they use echolocation (eck-oh-loh-KAY-shun) to forage, search, for food. Echolocation is the process of detecting objects by sending out sounds and listening to the sounds that bounce back from the objects. Old World leaf-nosed bats fly with their mouth closed and send out sounds through their nose, as opposed to most bats that use their mouths. These bats can send out sound in one frequency and listen to the sounds bounced back on another frequency.

Observations show they catch their prey in flight. Many hunt close to the ground, such as the Old World leaf-nosed bat of the Congo.

TO GROUP OR NOT TO GROUP

The first accounts of Old World leaf-nosed bats came in 1831, and the family's classification still remains uncertain. Some scientists consider Old World leaf-nosed bats a subfamily of horseshoe bats. Other researchers maintain that both groups are distinct families, as they are in this reference.

These bats mate during the fall and females do not become fertilized until the following year. Females generally give birth to a single offspring each year. When the offspring become independent and sexually mature depends upon the species and where they live.

OLD WORLD LEAF-NOSED BATS AND PEOPLE

These bats eat many insects that are considered pests to people. Some species have been harmed by humans destroying their habitat.

CONSERVATION STATUS

Some of the species in this family are common and others are rare and vulnerable to threats. Since little is known about many species in this family, the vulnerability of these bats is not fully understood. Out of the species that the IUCN lists, two are classified as Critically Endangered, facing an extremely high risk of extinction, dying out, in the wild; fifteen as Vulnerable facing a high risk of extinction, and twenty-three as Near Threatened, not currently threatened, but could become so.

TRIDENT LEAF-NOSED BAT (Asellia tridens): SPECIES ACCOUNT

Physical characteristics: These bats have a feature on their nose that resembles a trident, which is a spear with three prongs. The noseleaf is made up of the horseshoe-shaped lower part, the triangle-shaped central part, and three spear-like projections. The nostrils are located in the front, and there is a frontal sac behind the noseleaf. The ears are large and nearly hairless. Fur color ranges and includes grayish, pale yellow, and orange-brown. Some trident leaf-nosed bats in Egypt have medium- to dark tan-colored fur. These bats have large ears and pale faces.

Geographic range: These bats are found in Morocco, Algeria, Egypt, Libya, Sudan, the Arabian Peninsula, and Pakistan.

Habitat: These bats live in arid (extremely dry) environments. They have often been observed roosting in caves and artificial structures, such as tunnels and old temples. Species have also been spotted roosting in underground tunnels and under the iron roof of a shed in Iraq in June, when the temperature inside the shed was an estimated 100.4°F (38°C).

Diet: Trident leaf-nosed bats eat beetles, bees, ants, and wasps.

Behavior and reproduction: Trident leaf nosed bats catch their prey (animals hunted for food) primarily while they are flying. They also may snatch up prey from the ground and other surfaces. These bats forage in vegetated areas and can travel far across desert areas for food.

Roosts of several hundred individuals have been observed. One researcher in 1980 discovered a roost of about 5,000 individuals. When exiting and entering roosts, these bats have been observed flying in small groups and low to the ground. In Iraq, these bats travel to cellars and tombs when they hibernate, from mid-September to mid-November. They then return to their summer roosts in April.

Trident leaf-nosed bats and people: By destroying their local habitats, there is some evidence that humans have caused a decrease in the bats' population.

Conservation status: The trident leaf-nosed bat is not considered to be threatened. ∎

FOR MORE INFORMATION

Books:

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

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

Nowak, Ronald M. "Old World Leaf-nosed Bats." Walker's Mammals of the World 5.1 Online. Baltimore: Johns Hopkins University Press, 1997. http://www.press.jhu.edu/books/walkers_mammals_of_the_world/chiroptera/chiroptera.hipposideridae.html (accessed on July 5, 2004).

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:

Barr, Brady, and Margaret Zackowitz. "Going Batty." National Geographic World (October 2001): 12.

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

Web sites:

"Bat." World Almanac for Kids. http://www.worldalmanacforkids.com/explore/animals/bat.html (accessed on July 5, 2004).

Van Ryckegham, Alain. "How Do Bats Echolocate and How Are They Adapted to This Activity?" ScientificAmerican.com. http://www.sciam.com/askexpert_question.cfm?articleID=000D349B-6752-1C72-9EB7809EC588F2D7 (accessed on July 5, 2004).

"Jungle: Virtual Jungle Survival." BBC Science and Nature. http://www.bbc.co.uk/nature/programmes/tv/jungle/vjsurvival.shtml (accessed on July 5, 2004).