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Cheiromeles torquatushairless bat

By Paul Thomson

Geographic Range

Malay Peninsula, Sumatra, Java, Borneo, Philippines. Also recorded from the islands of Penang, Singapore and Tioman.

Habitat

Naked bats roost in hollow trees, caves, buildings, rock crevices, and holes in the earth.

Physical Description

The naked bat is a striking member of the Molossidae. It is virtually hairless, except for short, fine hairs on the head and tail membrane, and black, bristly hairs around the neck, on the first toe of the hind foot (probably used for grooming) and on the throat sack, which produces a strong-smelling secretion. Males secrete the substance by a series of small pores, females by a single large orifice (Lekagul and McNeely, 1977). Both sexes also possess a pouch along the sides of the body, formed by a fold of skin that runs from the upper arm to the upper part of the leg. The pouches open towards the rear and the wings are pushed into them by the hind feet. In this way, the bat can move about relatively freely on all four limbs. C. torquatus has the thickest jaws, widest face, and some of the broadest-tipped wings in the entire family. The head is relatively large and broad with a well-developed posterior sagittal crest. Unlike most Molossidae, the ears are separate, small and triangular, and the lips are smooth. The muzzle lacks a noseleaf and the snout projects well beyond the bottom jaw. The thick, elastic skin is almost black and contains many wrinkles and folds. The thick tail protrudes well over half its length. The wings are attached to the midpoint of the back. The first toe of each hind foot is opposable and equipped with a flattened nail rather than a claw. The dental formula is 1/1, 1/1, 1/2, 3/3 x 2 = 26. The upper incisors are robust, short and protrude forward. There is a diastema between the upper incisor and canine (Lekagul and McNeely, 1977). Head and body: 132-145 mm; tail: 56-71 mm. Weight: 167-196 grams.

  • Range mass
    167 to 196 g
    5.89 to 6.91 oz
  • Range length
    115 to 145 mm
    4.53 to 5.71 in

Reproduction

C. torquatus usually has two offspring. The mammae are positioned near the opening of the pouch, which is present in both sexes and runs along the sides of the body. It was traditionally thought that the young were carried and nursed in the pouch. However, according to Nowak (1991) the young are probably left in the roost when the parents leave on their evening flights.

  • Average number of offspring
    2

Behavior

C. torquatus is gregarious, as roosts of nearly a thousand are found and a colony in a cave in Borneo totaled 20,000 (Nowak, 1991). They leave their roost early in the evening, and feed quickly and directly, more boldly than smaller bats which move cautiously to avoid predators such as owls and bat hawks. They use echolocation to hunt for food, and clicking sounds are audible during echolocation.

Communication and Perception

Food Habits

C. torquatus is insectivorous. The diet primarily consists of termites and other insects, hunted either over clearings and fields or above the forest canopy. Wastes are eliminated as both feces and oral pellets.

Economic Importance for Humans: Positive

Since C. torquatus live in large numbers they consume vast quantities of insect pests.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Farmers in Malaya believe that C. torquatus feeds on paddy, gathering grain from ripe ears to store in the roost. However, it is more likely that rats, which share this habitat with bats, are responsible for the grain found inside hollow trees (Medway, 1978).

Conservation Status

Listed as Lower Risk/Near Threatened by the International Union of Conservation of Nature and Natural Resources (IUCN).

Other Comments

For excellent photos of C. torquatus, visit Walker's Mammals of the World online at

http://www.press.jhu.edu/books/walker/chiroptera/images/image.chiroptera.molossidae.cheiromeles.html

Contributors

Paul Thomson (author), University of Michigan-Ann Arbor, Ondrej Podlaha (editor), University of Michigan-Ann Arbor.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Forest Department Sarawak, Malaysia, August 15, 2001. "Naked Bat (Cheiromeles torquatus)" (On-line). Accessed October 6, 2001 at http://www.forestry.sarawak.gov.my/forweb/wildlife/mgmt/tpa/nbat.htm.

Freeman, P. March 31, 1981. A Multivariate Study of the Family Molossidae (Mammalia, Chiroptera): Morphology, Ecology, Evolution. FIELDIANA Zoology, New Series, No. 7: 87-88.

Hill, J., J. Smith. 1984. Bats: A Natural History. London: British Museum (Natural History).

Hilton-Taylor, C. 2000. "2000 IUCN Red List of Threatened Species" (On-line). Accessed October 11, 2001 at http://www.redlist.org/search/details.php?species=4601.

Lekagul, B., J. McNeely. 1977. Mammals of Thailand. Bangkok: Sahakarnbhat.

Medway, L. 1978. The Wild Mammals of Malaya (Peninsular Malaysia) and Singapore. Kuala Lumpur: Oxford University Press.

Nowak, R. 1991. Walker's Mammals of the World. Baltimore and London: The Johns Hopkins University Press.

Sarawak Forest Department and WCS, June 23, 2001. "Lords of the Night" (On-line). Accessed October 6, 2001 at http://www.mered.org.uk/saraweb/animals/Bats.htm.

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