Common sheath-tailed bat (Taphozous georgianus)
|Also known as:||common sheathtail bat, common sheath-tail bat, sharp-nosed bat, sharp-nosed tomb bat, unpouched freetail bat|
|Size||Forearm length: 6.6 - 7.4 cm (2)|
Adult weight: 19 - 41 g (2)
Weight at birth: 7 - 8 g (3)
- The common sheath-tailed bat belongs to a group known as the ‘tomb bats’.
- When roosting, the common sheath-tailed bat clings to rock surfaces with a characteristic spider-like stance, its forearms outstretched.
- Like other tomb bat species, the common sheath-tailed bat has a prominent tail.
- Common sheath-tailed bats give birth to one young per breeding season.
- Only the right ovary of the female common sheath-tailed bat is functional.
The common sheath-tailed bat is classified as Least Concern (LC) on the IUCN Red List (1).
The common sheath-tailed bat (Taphozous georgianus) is a large Australian bat that can often be seen in a characteristic roosting position, clinging close to rock surfaces in a spider-like manner, with outstretched forearms (2).
The upperparts of the common sheath-tailed bat are covered in dark brown fur, with the individual hairs having a creamy-brown base. The underparts are a lighter shade, and fine, gingery-grey hairs run along the under surface of the arm (2).
As in other sheath-tailed bat species, also known as tomb bats (4), the common sheath-tailed bat has a short but quite prominent tail (2), which actually pierces through the tail membrane, making the tip clearly visible (4). Female common sheath-tailed bats have two mammae (5), and unlike similar species, such as Hill’s sheath-tailed bat (Taphozous hilli), males of the common sheath-tailed bat do not possess neck pouches (2).
Bats are the only mammals to possess true, flapping wings, which consist of a wing membrane that provides the animal with a high degree of manoeuvrability in flight. The wing membrane is formed from a double layer of skin which stretches out between the body and the four elongated fingers on each hand, with blood vessels and nerves running between the two layers (6).
The common sheath-tailed bat occurs in parts of northern and western Australia (2) (7), including Western Australia, Queensland and the Northern Territory (3).
The preferred habitats of the common sheath-tailed bat are areas with steep, rugged, rocky slopes, such as escarpments (8). This species roosts in caves and rock shelters (2), as well as in old mines (9), and is usually found at high elevations, with cool minimum temperatures and low annual rainfall. However, the common sheath-tailed bat is also found in riparian and woodland areas (8).
Various rock types are used as maternity sites by the common sheath-tailed bat, with limestone caves frequently being chosen (10).
A strong flier, the common sheath-tailed bat is an agile and active species (3), flying high up in open areas in search of food (11).
This species is an insectivore (3) (12) (13) and hunts its prey on the wing (9) (13). Beetles form the bulk of the common sheath-tailed bat’s diet, but other insects are also eaten. Hunting alone, a common sheath-tailed bat finds food by flying slowly in a straight line over the feeding grounds at night, following a grid pattern over bushes and water (9) and detecting insects in mid-air using echolocation (6). During a feeding session, the common sheath-tailed bat may periodically rest on rocks next to cracks and fissures, which it will squeeze into if it is disturbed (9).
Groups of common sheath-tailed bats at roost sites are relatively small, with many consisting of fewer than 20 individuals (14), usually hanging more than 50 centimetres away from each other (9). The common sheath-tailed bat is reported to regularly relocate its roosting site (14), and can be found clinging in a spider-like manner to walls and ceilings in a variety of caves, from small cracks to large limestone caverns (10).
The common sheath-tailed bat has one breeding season per year (3) (15) (16). In central Queensland, mating occurs between late August and early September (3) (14), with young being born in late November or early December (3) (5) (14). However, the timing of breeding varies depending on the location, and in other areas young are reported to be born as early as October (5) (16), or as late as April (3). Interestingly, only the right ovary of the female common sheath-tailed bat is functional (16).
The gestation period of the common sheath-tailed bat is thought to be about four months (3) (16), after which time the female gives birth to a single young which is born with fur and with open eyes (3) (5) (14). The young sheath-tailed bat becomes independent at about three to four weeks old, and is almost full-grown at three months of age (3) (14). Female common sheath-tailed bats first reproduce at 9 months of age, while males do not begin mating until they are 21 months old (3) (5) (14). Breeding colonies of the common sheath-tailed bat are usually relatively small, and even the largest colony rarely exceeds several hundred individuals (10).
In the winter months, the common sheath-tailed bat has been observed in a state of torpor, with its body processes slowed to a fraction of their normal rate. Torpid bats roost in cool, shallow caves or near the entrance of large caves where there is cold air movement. If temperatures are very low, the common sheath-tailed bat may roost in a sunny patch of the cave wall near to the entrance. Torpid bats are still active, and quickly retreat to inner parts of the cave if disturbed (10).
Although there are no major threats currently affecting the common sheath-tailed bat, this species is vulnerable to disturbance from human visitors to its roosting caves, and may also be affected by the destruction of these areas for mining. Land clearance and degradation for agriculture poses a further potential threat to this species, by reducing the amount of feeding habitat available (9).
As the common sheath-tailed bat is not currently at risk of extinction, there are no known conservation measures targeted specifically towards this species at present.
Learn more about bats and their conservation:
Bat Conservation International:
The Bat Conservation Trust:
IUCN/SSC Bat Specialist Group:
Find out more about bat conservation in Australia:
Bat Conservation & Rescue QLD. Inc.:
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- Echolocation: detecting objects by reflected sound. Used by bats and odontocete cetaceans (toothed whales, dolphins and porpoises) for orientation and to detect and locate prey.
- Gestation: the state of being pregnant; the period from conception to birth.
- Insectivore: an organism that feeds mainly on insects.
- Mammae: the organs of females that produce milk. Also known as mammary glands.
- Ovary: the female reproductive organ that produces ova, or eggs.
- Riparian: relating to the banks of rivers and streams.
- Torpid: sluggish and inactive.
- Torpor: a sleep-like state in which the body processes slow to a fraction of their normal rate.
IUCN Red List (August, 2012)
- Parish, S., Richards, G. and Hall, L. (2012) A Natural History of Australian Bats: Working the Night Shift. CSIRO Publishing, Victoria, Australia.
- Nowak, R.M (1999) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
- Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
- Hayssen, V.D., Van Tienhoven, A. and Van Tienhoven, A. (1993) Asdell's Patterns of Mammalian Reproduction: A Compendium of Species-Specific Data. Cornell University Press, New York.
- Burnie, D. (2001) Animal. Dorling Kindersley, London.
- Wilson, D.E. and Reeder, D.M. (2005) Mammal Species of the World. A Taxonomic and Geographic Reference. Volume 1. Johns Hopkins University Press, Baltimore.
- Milne, D.J., Armstrong, M., Fisher, A., Flores, T. and Pavey, C.R. (2005) Structure and environmental relationships of insectivorous bat assemblages in tropical Australian savannas. Austral Ecology, 30: 906-919.
Australian Museum - Common sheathtail bat (August, 2012)
- Hamilton-Smith, E. and Finlayson, B. (Eds.) (2003) Beneath the Surface: A Natural History of Australian Caves. University of New South Wales Press, New South Wales.
- Pavey, C.R. and Burwell, C.J. (2005) Cohabitation and predation by insectivorous bats on eared moths in subterranean roosts. Journal of Zoology, London, 265: 141-146.
- Altringham, J.D. (2011) Bats: From Evolution to Conservation. Oxford University Press, Oxford.
- Findley, J.S. (1993) Bats: A Community Perspective. Cambridge University Press Archive, Cambridge.
- Jolly, S. (1990) The biology of the common sheath-tail bat, Taphozous georgianus (Chiroptera, Emballonuridae), in central Queensland. Australian Journal of Zoology, 38(1): 65-77.
- Kunz, T.H. and Fenton, M.B. (Eds.) (2006) Bat Ecology. University of Chicago Press, Chicago.
- Kitchener, D.J. (1973) Reproduction in the common sheath-tailed bat, Taphozous georgianus (Thomas) (Microchiroptera : Emballonuridae), in Western Australia. Australian Journal of Zoology, 21(3): 375-389.