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Tadarida australiswhite-striped free-tailed bat

By Nathaniel Minnick

Geographic Range

Tadarida australis (white-striped free-tailed bats) occurs naturally in Australia. These bats range through the entire continent, excluding the northern coastal area. (Hall and Richards, 1972; Hall and Richards, 1972; Strahan, 1995)

During Australia's coldest months (June through August), these bats migrate north to areas with warmer nighttime temperatures and, therefore, higher insect populations. (Bullen and McKenzie, 2005)

Habitat

White-striped free-tailed bats can be found in lowland, tropical and scrub forests. They roost in dead, hollow trees or tree stumps and in attics of buildings, barns, and silos in human-dominated landscapes. (Lumsden and Bennett, 1995; Strahan, 1995)

Physical Description

Considered the largest Australian molossid, T. australis individuals weigh up to 40 g and have a maximum length of 100 mm. Forearm length ranges from 57mm to 63mm and the tail extends 55mm from the body. The large, forward pointed ears can be 25mm in length. A short tragus is present. The upper lip is deeply wrinkled, and these bats have single incisors on each premaxilla. Both sexes have a throat pouch. (Menkhorst and Knight, 2001; Strahan, 1995)

Fur color varies from chocolate brown to dark brown dorsally and lighter ventrally. The common name, white-striped free-tailed bat, refers to a characteristic symmetrical pattern of white fur on the body. This runs from the front to the back where the wings fold against the torso. As a member of the family Molossidae, T. australis has a free tail extending through a well-formed tail membrane (uropatagium). (Strahan, 1995)

  • Sexual Dimorphism
  • male larger
  • Range mass
    25 to 40 g
    0.88 to 1.41 oz
  • Range length
    85 to 100 mm
    3.35 to 3.94 in

Reproduction

Social behavior in this species has not been reported. They are considered mainly solitary, but they may roost together in small groups of up to ten. Maternity roosts can reach numbers up to one hundred. Ellis (1993) suggested that these bats may fly into each other as some type of courtship. (Ellis, 1993; Strahan, 1995)

Female white-striped free-tailed bats synchronize copulation and ovulation. Mating occurs in August, as females are monoestrous, and birth occurs in December or January. Females give birth to a solitary offspring. Males attain sexual maturity after one and a half years, whereas females reach maturity at nine months. (Kitchener and Hudson, 1982)

  • Breeding interval
    White-striped free-tailed bats breed once per year.
  • Breeding season
    Breeding occurs in August.
  • Range number of offspring
    1 to 1
  • Range gestation period
    4 to 6 months
  • Range weaning age
    4 to 5 months
  • Range age at sexual or reproductive maturity (female)
    8 to 9 months
  • Range age at sexual or reproductive maturity (male)
    16 to 22 months

Parental investment is not well documented, however, as in most bat species, females are likely to be the sole caregivers for their offspring. (Kitchener and Hudson, 1982)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

No information on the lifespan of this species was found. In Tadarida brasiliensis, a related species, female lifespans have been documented at about seven years. (Walton and Richardson, 1989)

Behavior

White-striped free-tailed bats fly fast and high above tree canopies as they forage and travel. Their high and fast flight makes them difficult to capture and study. They are nocturnal, hunting at night and roosting during the day. Unlike some other bats, T. australis has adequate ground mobility and doesn’t seem to have difficulty “running." Considered mainly solitary, T. australis may be found in small groups of ten. White-striped free-tailed bats do not hibernate, but do enter torpor. (Bullen and McKenzie, 2005; Herr, 1998; Menkhorst and Knight, 2001; Strahan, 1995)

Home Range

The home range size of T. australis has not been documented.

Communication and Perception

Tadarida australis uses echolocation to detect flying insects, and is one of the few bat species with calls audible to human ears. They mainly use constant frequency echolocation but some frequency modulated components have been recorded as well. The constant frequency calls range in bandwidth from 10.5 to 15 kHz. Tactile sense has developed to detect when prey come into contact with the uropatagium, which is an important feature for capturing insects. Molossidae species reflexively close their mouths when insect prey brush the hairs near their jaws. Although T. australis uses its uropatagium when capturing ground and aerial prey, it is also likely to use the same reflexive jaw-shutting behavior as other Molossidae. (Bullen and McKenzie, 2005; Herr, 1998; Menkhorst and Knight, 2001; Strahan, 1995; Walton and Richardson, 1989)

Little research has been done on communication in white-striped free-tailed bats. As in most mammals, chemical and auditory communication is likely to be important.

Food Habits

Tadarida australis is insectivorous. These bats mainly capture insects in flight but may also walk on the ground and foliage to capture insects on surfaces. (Strahan, 1995; Strahan, 1995)

  • Animal Foods
  • insects

Predation

Macroderma gigas, Australian false vampire bats, may prey on T. australis and the remains of T. australis have been found in pellets of Ninox strenua, powerful owls. (Bullen and McKenzie, 2005; Bullen and McKenzie, 2005)

Ecosystem Roles

Tadarida australis plays a crucial role in regulating insect populations.

Commensal/Parasitic Species
  • Flies in the family Nycteribiidae are an ectoparasite of many microchiropterans.

Economic Importance for Humans: Positive

Insectivorous bats, such as white-striped free-tailed bats, can limit populations of agricultural insect pests. Bat guano is also valuable as fertilizer.

  • Positive Impacts
  • produces fertilizer
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of T. australis on humans.

  • Negative Impacts
  • household pest

Conservation Status

The IUCN lists T. australis as at lower risk for endangerment. Deforestation results in loss of roosting and foraging sites. Also, pesticides can accumulate in the bodies of these insectivorous bats and threaten many species of bats.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Nathaniel Minnick (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

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

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

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

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight 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

Bernard, R., G. Cumming. 1997. African bats: Evolution of reproductive patterns and delays. The Quarterly Review of Biology, 72/3: 253-274.

Bullen, R., N. McKenzie. 2005. Seasonal range variation of Tadarida australis (Chiroptera: Molossidae) in Western Australia: the impact of enthalpy. Australian Journal of Zoology, 53: 145-156.

Ellis, M. 1993. Unexplained behaviour in the white-striped mastiff-bat Tadarida australis. Australian Zoologist, 29/1-2: 103-104.

Hall, L., G. Richards. 1972. Notes on Tadarida-Australis Chiroptera Molossidae. Australian Mammalogy, 1: 46-47.

Herr, A. 1998. "Aspects of the ecology of insectivorous forest-dwelling bats (Microchiroptera) in the western slopes of the Australian alps" (On-line pdf). Accessed March 21, 2006 at http://csusap.csu.edu.au/~aherr/thesis/thesis.pdf.

Kitchener, D., C. Hudson. 1982. Reproduction in the Female White-Striped Mastiff Bat, Tadarida australis (Gray). Australian Journal of Zoology, 30: 1-14.

Lumsden, L., A. Bennett. 1995. Bats of a semi-arid environment in South-eastern Australia: Biogeography, ecology and conservation. Wildlife Reserve, 22: 217-240.

Lumsden, L., A. Bennett. 2005. Scattered trees in rural landscapes: foraging habitat for insectivorous bats in south-eastern Australia. Biological Conservation, 122/2: 205-222.

Menkhorst, P., F. Knight. 2001. A Field Guide to the Mammals of Australia. Oxford: Oxford University Press.

Strahan, R. 1995. The Mammals of Australia. Australia: Reed Books.

Tidemann, C., S. Flavel. 1987. Factors affecting choice of diurnal roost site by tree-hole bats (Microchiroptera) in South-Eastern Australia. Australian Wildlife Reserve, 14: 489-73.

Tilley, S. 1982. The diet of the powerful Owl, Ninon strenua, in Victoria. Australian Wildlife Reserve, 9: 157-175.

Walton, D., B. Richardson. 1989. Fauna of Australia Volume 1B: Mammalia. Canberra: Australian Government Publishing Service.

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