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.
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.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; ultrasound ; echolocation ; chemical
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of T. australis on humans.
Negative Impacts: household pest
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
Tadarida australis plays a crucial role in regulating insect populations.
Commensal/Parasitic Species:
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.
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Tadarida australis (white-striped free-tailed bats) occurs naturally in Australia. These bats range through the entire continent, excluding the northern coastal area.
During Australia's coldest months (June through August), these bats migrate north to areas with warmer nighttime temperatures and, therefore, higher insect populations.
Biogeographic Regions: australian (Native )
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.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest ; scrub forest
Other Habitat Features: urban ; suburban ; agricultural
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.
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.
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).
Range mass: 25 to 40 g.
Range length: 85 to 100 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: male larger
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.
Known Predators:
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.
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.
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.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Parental investment is not well documented, however, as in most bat species, females are likely to be the sole caregivers for their offspring.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Australia's largest molossid, the White-striped Free-tail Bat (Tadarida australis) is found on Kangaroo Island along with other Australian locales. The most notable mammal present is the endemic Kangaroo Island Kangaroo (Macropus fuliginosus fuliginosus), the icon for whom the island was named upon European discovery in 1802. A smaller marsupial present on the island is the Tammar Wallaby (Macropus eugenii). An endemic dasyurid is the Critically Endangered Kangaroo Island Dunnart (Sminthopsis aitkeni), which is found only in the west of the island in Eucalyptus remota/E. cosmophylla open low mallee, E. baxteri low woodland or E. baxteri/E. remota low open woodland. The Common Brush-tailed Possum (Trichosurus vulpecula) is a widespread folivore native to Australia.
Monotremes are also represented on the island. There is also an introduced population of the Duck-billed Platypus (Ornithorhynchus anatinus) in the western part of the island in Flinders Chase National Park. The Short-beaked Echidna (Tachyglossus aculeatus) is also found moderately widespread on Kangaroo Island.
Chiroptera species on Kangaroo Island include the Yellow-bellied Pouched Bat (Saccolaimus flaviventris), which species is rather widespread in Australia and also occurs in Papua New Guinea.Another bat found on the island is the Southern Forest Bat (Eptesicus regulus), a species endemic to southern Australia (including Tasmania).
Several anuran species are found on Kangaroo island: Brown Tree Frog (Litoria ewingii), Spotted Marsh Frog (Limnodynastes tasmaniensis), Painted Spadefoot Frog (Neobatrachus pictus), Brown Toadlet (Pseudophryne bibroni) and Brown Froglet (Crinia signifera).
The Heath Monitor (Varanus rosenbergi ) is a lizard that grows up to a metre in length, preying on smaller reptiles, juvenile birds and eggs; it is frequently observed on warmer days basking in the sunlight or scavenging on roadkill. The Black Tiger Snake (Notechis ater) is found on Kangaroo Island. Another reptile particularly associated with this locale is the Kangaroo Island Copperhead (Austrelaps labialis).
The Glossy Black Cockatoo (Calyptorhynchus lathami) is found on the island, especially in the western part, where its preferred food, fruit of the Drooping Sheoak, is abundant. The Kangaroo Island Emu (Dromaius baudinianus) became extinct during the 1820s from over-hunting and habitat destruction due to burning.
Marine mammals that are observed on the island include the Australian Sea Lion (Neophoca cinerea) and New Zealand Fur Seal (Arctocephalus forsteri), each species of which is native to Kangaroo Island, and abundant at Admiral's Arch as well as at Seal Bay.
Kangaroo Island is not so adversely impacted by alien species grazers as parts of the mainland. No rabbit species are present on the island, and introduced (but escaped) Domestic Goats (Capra hircus) and pigs (Sus scrofa) have generated only minor issues. However, a Koala (Phascolarctos cinereus) population introduced to the island in the 1920s has caused significant damage to certain woodland communities, especially to Manna Gum trees.
The white-striped free-tailed bat (Austronomus australis) is a species of bat in the family Molossidae. Its echolocation calls are audible to humans, which is a characteristic found in only a few microbat species.[3] The species was formerly classified as Tadarida australis.[4]
The first description of the species was published in 1838 by John Edward Gray, in a review of material at the British Museum of Natural History. The author noted the source of the specimen, a skin and skull, as New South Wales and placed it with the genus Molossus. When providing a description in Furred Animals of Australia, Ellis Troughton suggested that the specimen examined by Gray was obtained at Camden, a property owned by John Macarthur. Troughton first proposed the species be distinguished as a monotypic genus Austronomus, this arrangement was eventually resurrected when the taxon was separated from the previously accepted alliance with the widespread genus Tadarida.[5][6]
Gregorin and Cirranello in their work found that Koopman[7] treated T. kuboriensis, as a subspecies of T. australis, and formed a clade with T. australis.[8] These two species display eight characteristics that make them distinctly morphologically from the other Tadarida. The most significant characteristic is a keel present between the nostrils, a synapomorphy combining this clade.[8] Likewise, T. kuboriensis and T. australis lack hair on the tragus and do not have thorn-like hairs on the face. The presence of hair on the tragus is a synapomorphy for non-Australian Tadarida.[8] With the relationship between T. kuboriensis and T. australis and their morphological uniqueness acknowledged, when compared with other species of Tadarida, both species should be recognized under the established generic name Austronomus Troughton 1943 (type species Austronomus australis) Gray, 1834.[8]
There has been much consideration given to the seniority of what genus name to use for the white-sided free-tailed bat. The international Commission on Zoological Nomenclature (ICZN) recognises Tadarida (Rafinesque, 1814) as the senior authority before Nyctinomus, (Geoffroy, 1818). Therefore, Tadarida, Rafinesque 1814 has precedence.
The white-striped free-tailed bat is robust in build[6] and the largest of the eleven Australian Molossids. The colour of the pelage is a deep chocolate brown, with well defined white stripes beneath the wing; occasional patches of white may appear at the upper ventral side. Individuals have a mass of 33 to 41 grams, and average of 37 g, and a head and body length of 85 to 100 millimetres.[6] The free tail extends 40 to 55 mm from the body and can be folded during high speed flight to reduce drag.[9][10] The forearm length range is 57-63 mm.[6] It has a condylobasal length of 23–24 mm. The skull is dorso-ventrally flattened. The baculum is divided into three lobes.[11]
This species has a wingtip shaped similarly to the crescent form found on fast-flying birds and on the caudal fins of fast-swimming fish.[12] These tips have leading edges that curve around to chordwise orientation and have trailing edges with aft-sweep or zero-sweep over the outer half of the tip. This bat's wings are considered as having low camber sections with faired humerus and radius bones, typical leading-edge flaps and surface disjunctions and protuberances. This allows this interceptor species to optimise for least drag generation at the expense of maximum lift ability at high speeds.[13] The white-striped free-tailed bat can reach speeds of up to 17 m/s.[10]
The large, forward pointed ears are 20 to 25 mm in length and assist in their aerodynamic lift.[10] The ears are exceptionally broad and noticeably ribbed.[6] A short hairless tragus is present and also points forward. The inner margins of the ears touch, but are not joined where they meet on the head.[8] The upper lip is deeply wrinkled, and this species have single incisor teeth on each of the frontal cranial bones of the upper jaw. Both sexes have a throat pouch.[9] The colour of the skin is very dark, blackish, with a slight pink hue.[6] Fur colour varies with dark brown dorsally and lighter ventrally. A distinctive pattern of white fur on each side of the body progresses from the front to the back where the wings fold against the body, giving this species its common name, white-striped free-tailed bat. This species displays sexual dimorphism with the male being larger.
The white-striped free-tailed bat typical call has been recorded between 10-15 kHz.[10] The species emits one to two calls per second and unlike the ultrasonic signals of most microchiropterans these are audible to humans. The sounds is described as "pink-pink-pink" or a "metallic ting-ting-ting".[14][6] Research by Herr and Klomp into the white-striped free-tailed bat's calls showed that vocalisation changed at different stages of flight.[15] In the initial stages of flight, after release, this species used steep frequency modulated pulse, from 27 kHz to 13 kHz, changing to a low frequency modulated pulse when flying above a canopy. Once there the call structure changes to the more typical white-striped free-tailed bat call with a constant frequency with a divergence between maximum and minimum frequency of 5 kHz. All echolocating bats use a terminal phase buzz call to locate, close in and capture their prey.[16]
An endemic species to Australia, the white-striped free-tailed bat is widespread and common. They are seasonally migratory but not recorded in the northern third of the continent nor previously known on the southern island of Tasmania.[6][9] However, surveys conducted in Tasmania between 2009 and 2013 indicated the species is present and maybe a periodic visitor or vagrant in Tasmania.[17] In Western Australia this species is restricted south of the 20°S latitude during the breeding season, the austral spring and summer, then extending north in the winter.[18][19] This species can be found in most habitats from closed forest to open flood plain, and occurs in urban areas, in regions across temperate and subtropical Australia.
In the Greater Brisbane Region of South East Queensland the white-striped free-tail bat uses over-mature to dead eucalypt species with large tree diameters (>89 cm) as roost habitats.[20] These trees have developed large trunk cavities, often extending throughout the trunk and major branches.[20] The bats access these cavities through multiple unobstructed branches and/or trunk hollows.[21] This strategy also allows the bats a direct flight path when leaving the roost cavities which may result in energy savings for the bats and reduce the exposure to predators.[22][23]
Although single bats spend most of their daytime in separate day-roosts, they spent an average of one day in every eleven within the communal roost.[20] The bats also visited the communal roost for periods of time during their nocturnal activity, and some individuals were recorded twice as often frequenting the communal roost during the night compared with the day.[24]
This bat species is a highly colonial tree-dweller, so that large internal hallows are an important feature in selecting suitable maternity roost sites as population numbers increase during parturition. Therefore, the quality and size of roost space is more important than the selection of a particular species of tree in maternity roost choice.[20][25]
The white-striped free-tailed bat is a specialized high-altitude, fast-flying interceptor insectivore.[26][27] Their diet consists principally of moths, beetles and bugs.[10]
In South East Queensland, white-striped free-tailed bats demonstrated a significant preference for foraging above flood plain habitat and does not prefer to feed above remnant forests.[28] In northern Australian urban areas, foraging individuals preferred and were in greater concentrations over grassland with few trees, such as golf courses, than over riparian areas, new urban developments, and suburbs that had been established for between 20–50 years.[29] White-striped free-tailed bats once they emerge from their roosts fly rapidly and directly to their foraging area, with individual bats flying up to 20 kilometres (12 mi) to reach their feeding areas. However, some populations have a more localised foraging area. In the greater Brisbane area, foraging areas are usually within 2.5 km (1.6 mi) of day roost and 6.2 km (3.9 mi) of communal roosts.[28] On arrival they reduce their commuting flight speed to a lower sustainable flight speed that allows them to hunt in the foraging area for some hours.[28][11] The species is agile on hard ground or other firm surfaces.[6] Some researchers report that the bat will also scurry around on the ground chasing ground-dwelling insects such as beetles, bugs, grasshoppers and ants. They are able to do this by folding their wings away neatly so that their forearms are free, retracting their tail membrane and scampering around on their thumbs and hind feet.
Males do not have the ability to store sperm in their vesicular follicles during the winter period, therefore breeding commences late in August. Females give birth to one young between mid-December and mid-January, which indicates a gestation period of about 14 weeks.[30]
The white-striped free-tailed bat (Austronomus australis) is a species of bat in the family Molossidae. Its echolocation calls are audible to humans, which is a characteristic found in only a few microbat species. The species was formerly classified as Tadarida australis.
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