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Miniopterus australislittle long-fingered bat

By Casey Wilke

Geographic Range

Miniopterus australis inhabits the subtropical coastal regions of Indonesia, Philippines, New Guinea, and Australia. In Australia, its range does not exceed the north-eastern coast. Miniopterus australis has a southern range limit in north-eastern New South Wales with a latitude of 31°15' S. The southern limit may be due to the close relationship M. australis has with Miniopterus schreibersii (common bent-wing bat). (Dwyer, 1968; Dwyer, 1983; Kithener and Suyanto, 2002)

Habitat

Most M. australis roost in caves, but it is also known to roost in abandoned mines, tunnels, water drains, buildings, and tree hollows. The nursery sites are usually located in limestone caves. They appear to forage in environments at the edges of forests. (Dwyer, 1968; Rhodes and Hall, 1997; Schulz, 1997)

It appears that M. australis is reproductively dependent on M. schreibersii for warmth in these caves. Miniopterus schreibersii is almost twice the size of M. australis, and heat the cave nicely for the young of both species. This could be why the range of M. australis is concurrent with the southern range of M. schreibersii. Miniopterus australis does not migrate to a winter roost. (Dwyer, 1968; Schulz, 1997)

  • Other Habitat Features
  • caves

Physical Description

Miniopterus australis lacks a nose leaf. It appears grayish-black, but changes color during the year to a fawnish-brown. A closer look reveals a coat with pale brown under-fur topped with a chocolate brown color. Both males and females molt. However, females tend to molt later than males because they may be lactating during the normal time of molting. (Dwyer, 1968; Dwyer, 1983)

Miniopterus australis is closely related to and looks much like M. schreibersii, but is slightly smaller. It weighs 7 to 8 g and has a total length of 86 to 96 mm. Males and females do not exhibit any type of dimorphism; they are relatively the same size and weight, except for pregnant females who will gain 2 to 3 g. The tail is just as long as the head and body together (43 to 48 mm), and the haired patagium covers most of the tail. The forearm of this species is a total of 36 to 40 mm long. (Dwyer, 1968; Dwyer, 1983)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    7 to 8 g
    0.25 to 0.28 oz
  • Range length
    86 to 96 mm
    3.39 to 3.78 in

Reproduction

No information was found on the mating systems of M. australis. (Dwyer, 1968; Dwyer, 1983)

Miniopterus australis start to reproduce after 21 months of age. Copulation activity occurs during the winter months of June and July. Once mated, the females do not store the sperm; fertilization takes place right away in August. Although there is no delayed implantation, retarded embryonic development is experienced. The retarded development lasts from August to mid-September, when normal development resumes. (Dwyer, 1968; Dwyer, 1983)

Miniopterus australis, like M. schreibersii, chooses specific sites for nurseries in which to rear young. These nurseries are used year after year, with both species often together in one site. Miniopterus australis gives birth in the summer month of December after a gestation period of about four months. (Dwyer, 1968; Dwyer, 1983)

Although no reports were found for M. australis, newborn M. schreibersii weigh between 2 nd 3 g. Weaning of M. schreibersii occurs at about 2 months of age. Miniopterus australis is probably similar. (Nowak, 1999)

  • Breeding interval
    These bats appear to breed annually.
  • Breeding season
    Breeding occurs in June and July.
  • Range number of offspring
    1 to 1
  • Range gestation period
    180 to 195 days
  • Average age at sexual or reproductive maturity (female)
    21 months
  • Average age at sexual or reproductive maturity (male)
    21 months

Miniopterus australis is considered a juvenile up to 9 months, a yearling between 9 and 21 months, and an adult after 21 months of age. Mothers tend to the young, nursing and grooming them, but sometimes find that the cave becomes too warm. To cool themselves off, the mothers will leave the young hanging alone in the cave amd exit to the cool outdoors. Male parental care has not been described in this species. (Dwyer, 1983)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

The oldest recorded age of M. australis is five and a half years. This is based on an individual that was captured, marked, and recaptured. It is quite possible that they do live longer, but it has never been recorded. (Dwyer, 1968; Dwyer, 1983)

  • Range lifespan
    Status: wild
    5.5 (high) years

Behavior

Miniopterus australis is a nocturnal animal, found living in colonies. A study done on ultrasonic detection of M. australis revealed that these bats fly in open areas as well as in forested areas. This is an indication that M. australis reside in edge habitats. It has been recorded flying up to 59.5 kilometers from the nursery site, but no more than that. In essence, this species tend to stay in the locality of their nursery roost.

Miniopterus australis is most active in spring, summer, and fall (mid-September to February and March to May). During the late winter months (July and August), M. australis enters torpor. There were only two events where clusters of this species appeared sluggish in the fall.

Dwyer (1968) found that active M. australis would leave their roost when disturbed by a human observer. Sluggish bats would leave the roost after ten minutes up on entrance of an observer, and torpid bats remained inactive even a half hour after entrance of an observer.

Miniopterus australis starts to colonize a nursery site in early spring, anywhere from August to September. At that time, the colony consists of adult males and females. Around October and November, most males leave the colony, which will then consist of females, their young, and a few males. The females start to leave their young in February and March. The young leave in April, and the roost is considered abandoned until the following August. Miniopterus australis does colonize in the same roost as M. schreibersii. Juveniles, who are not counted in surveys, may also be located in the nursery site, but will roost in other locations as well. (Dwyer, 1968; Rhodes and Hall, 1997)

Home Range

The home range of M. australis does not exceed 59.5 km from the nursery site. (Dwyer, 1968)

Communication and Perception

Miniopterus australis is an echolocator. These animals use high pitch frequencies to locate their prey and avoid obstacles while flying. Because they are an edge habitat species, they use a mix of FM and CF calls. (Jones and Corben, 1993)

As mammals, it is likely that they use some visual cues to communicate, as well as scent (especially the mother locating her young in the nursury cave). Tactile communication undoubtedly takes place in the somewhat crowded caves, as well as between mothers and their offspring and mates. (Nowak, 1999)

Food Habits

Miniopterus australis emerge in the evening to forage. Using echolocation, they fly between shrub and canopy layers of extremely wooded areas and prey on the small bugs under the canopy. (Dwyer, 1968; Dwyer, 1983)

  • Animal Foods
  • insects

Predation

As individuals of M. australis fly from their shelters, they will sometimes be snatched by pythons or ghost bats (one of the predatory bat species). Other common predators are owls and foxes. Many young may fall to the floor of the nursery roost and be overtaken by beetles that inhabit the area. (Dwyer, 1983)

Ecosystem Roles

The most information that was found on the ecosystem roles of M. australis is that they are predators of small bugs. They probably havve some effect on local insect populations. To the extent that they and are also prey for pythons, owls, ghost bats, foxes, and beetles, they may help provide nourishment for those predatory species.

Economic Importance for Humans: Positive

Miniopterus australis is insectivorous, and likely consumes insect pests.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There was no information found on negative impact of M. australis.

Conservation Status

Miniopterus australis is abundant in Indonesia, New Guinea, and the northeastern coast of Australia. Because they are not a threatened or endangered species, there are no attempts to legally protect them. There is no special status for M. australis on either the IUCN or CITES lists. (Dwyer, 1983)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Casey Wilke (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Australian

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

World Map

acoustic

uses sound to communicate

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.

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.

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.

embryonic diapause

At about the time a female gives birth (e.g. in most kangaroo species), she also becomes receptive and mates. Embryos produced at this mating develop only as far as a hollow ball of cells (the blastocyst) and then become quiescent, entering a state of suspended animation or embryonic diapause. The hormonal signal (prolactin) which blocks further development of the blastocyst is produced in response to the sucking stimulus from the young in the pouch. When sucking decreases as the young begins to eat other food and to leave the pouch, or if the young is lost from the pouch, the quiescent blastocyst resumes development, the embryo is born, and the cycle begins again. (Macdonald 1984)

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

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.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

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).

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

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

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).

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

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

Dwyer, P. 1983. Complete Book of Australian Mammals. Sydney: Angus and Robertson.

Dwyer, P. 1968. The Biology, Origin, and Adaptation of Miniopterus australis (Chiroptera) in New South Wales. Australian Journal of Zoology, 16: 49-68.

Jones, G., C. Corben. 1993. Echolocation Calls from Six Species of Microchiropteran Bats in South-eastern Queensland. Australian - Mammology, 16/1: 35-38.

Kithener, D., A. Suyanto. 2002. Morphological Variation in Miniopterus pusillus and M. australis (sensu Hill 1992) in Southeastern Asia, New Guinea, and Australia. Records of the Western Australian Museum, 21: 9-33.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Rhodes, M., L. Hall. 1997. Bats of Fraser Island. Australian Zoologist, 30: 346-350.

Schulz, M. 1997. The Little Bent-wing Bat Miniopterus australis Roosting in a Tree Hollow. Australian Zoologist, 30: 329.

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