Grey-headed Flying Fox

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Grey-headed flying fox

Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Pteropodidae
Genus: Pteropus
Species: P. poliocephalus
Binomial name
Pteropus poliocephalus
(Temminck, 1825)
Distribution of P. poliocephalus
Distribution of P. poliocephalus

The grey-headed flying fox, Pteropus poliocephalus, is a fruitbat native to Australia. Members of the genus Pteropus include the largest bats in the world. The Pteropus genus has currently about 57 recognised species. Pteropus is primarily an island taxon, with 55 species having some or all of their distribution on islands. Only nine species are found in continental ares (five in Asia and four in Australia), and only two (Lyle's flying fox Pteropus lylei and the grey-headed flying fox) are restricted to continents.

Contents

[edit] Physical Characteristics

Adult grey-headed flying foxes have an average wingspan of over 1m and can weigh up to 1 kg. They are brown, with varying shades of grey on their head and back, and have an orange/brown mantle that fully encircles their neck.

[edit] Distribution

The Australian mainland is home to 56 species of bat. Of these, four species belong to the genus Pteropus: the little red flying fox, Pteropus scapulatus, the spectacled flying-fox, Pteropus conspicillatus, the black flying-fox, Pteropus alecto and the grey-headed flying-fox.

The grey-headed flying fox is endemic to the south-eastern forested areas of Australia, principally east of the Great Dividing Range. It extends from Bundaberg in southern Queensland to Geelong, Victoria, where it occupies a more extreme latitude than any other Pteropus species.

[edit] Roosting habits

During the day individuals reside in large roosts (colonies or 'camps') consisting of hundreds to tens of thousands of individuals. Colonies are formed in seemingly arbitrary locations. Roost vegetation includes rainforest patches, stands of Melaleuca, mangroves and riparian vegetation, but roosts also occupy highly modified vegetation in urban areas.

Grey-headed flying foxes exhibit a high seasonal fidelity to traditional roosts and return annually to the same locations. When undisturbed, roost locations can be stable for several decades and fidelity to some sites may even have pre-dated human settlement. An important determinant of roost size is food available within nightly foraging distances, commonly within 20 kilometres but up to 50 km. Another important determinant is the time of year, with the largest aggregations of individuals occurring during the mating season.

[edit] Reproduction

Matings are generally observed between March and May but the most likely time of conception is April. The majority of females reproduce once a year and give birth to a single young. Gestation is about 27 weeks and pregnant females give birth in September or October. The young are born altricial and are dependent on their mothers for food and protection. Females carry their young for the first three weeks during their nightly foraging trips and after this time young are left in the roost at night. Young are capable of independent flight in January at which time they commence foraging outside the colony. Young are weaned between February-April.

[edit] Life-span

The grey-headed flying fox is very long-lived for a mammal of its size. There are reports of individuals surviving in captivity for up to 23 years, and a maximum age of up to 15 years seems possible in the wild. Sometimes a bat in the wild can survive longer if it is not attacked during its lifespan.

[edit] Diet

Around dusk, grey-headed flying foxes leave the roost and travel up to 50 km a night to feed on pollen, nectar and fruit. The food sources utilised by the species include pollen and nectar from trees belonging to the genera Eucalyptus, Angophora, Melaleuca and Banksia, and fruits from a wide range of rainforest trees, including members of the Ficus genus. Grey-headed flying foxes, along with the three other Australian flying fox species, fulfill a very important ecological role by dispersing the pollen and seeds of a wide range of native Australian plants. The grey-headed flying fox is the only mammalian pollenivore, nectarivore and frugivore to occupy substantial areas of subtropical rainforests and so is of key importance to those forests.

Most vegetation communities used by the grey-headed flying fox produce foraging resources in seasonal but annually irregular superabundant pulses, and the grey-headed flying fox has adopted complex migration traits in response to such ephemeral and patchy food resources. However, there are some temporally and spatially reliable resources restricted to a small number of coastal vegetation communities in northern New South Wales and Queensland that may support smaller resident populations.

[edit] Conservation

The grey-headed flying fox is now a prominent federal conservation problem in Australia. Early last century the species was considered abundant with numbers estimated in the many millions. However, in recent years, direct evidence has been accumulating that the species is in serious decline. Current estimates for the species are about 300,000 and it has been suggested that the national population may have declined by as much as 30% in the last decade alone.

Grey-headed flying foxes are exposed to several threatening processes, including loss of foraging and roosting habitat, competition with the black flying fox, and mass die-offs caused by extreme temperature events. When present in urban environments grey-headed flying foxes are sometimes perceived as a nuisance. Cultivated orchard fruits are also taken but apparently only at times when other food items are scarce. Because the roosting and foraging habits of the grey-headed flying fox bring the species into conflict with humans, the species suffers from direct killing of animals in orchards and harassment and destruction of roosts. Negative public perception of the species has intensified with the discovery of three recently emerged zoonotic viruses that are potentially fatal to humans: Hendra virus, Australian bat lyssavirus and Menangle virus. However, only Australian bat lyssavirus is known from two isolated cases to be directly transmissible from bats to humans.

Recent research has shown that since 1994, more than 24,500 grey-headed flying foxes have died from extreme heat events alone. This is of increasing concern for the survival of this species now that climate models predict significant increases in the intensity, duration and frequency of such temperature extremes.

To answer some of the growing threats, roost sites have been legally protected since 1986 in New South Wales and since 1994 in Queensland. In 1999 the species was classified as ‘vulnerable to extinction’ in The Action Plan for Australian Bats[1], and the species is now protected by law across its range.

[edit] Wildlife rescue

Often flying foxes come to the attention of WIRES, the Australian wildlife care and rescue organisation, when reported as injured etc. A very high proportion of flying fox injuries are caused by fruit tree netting or barbed wire fences, both of which can can result in a slow and agonizing death for the animal if not rescued. Young flying foxes also come into the care of WIRES bat carers, who are specially trained to raise and rehabilitate. Although the chance of contracting Australian bat lyssavirus is extremely small, bat carers are inoculated for their own protection.

A baby flying fox usually comes into care after having been separated from its mother; reasons for separation can be wide and varied, including the death of the parent. Most babies are in a dehydrated and distressed state by the time they are rescued, and some are infested with maggots if injured. A young flying fox must be fed every 4 hours up to 6 times a day, and then as it grows it is introduced to blossoms and fruit. When the young flying fox is fully weaned around 10 to 12 weeks of age, it goes into a crèche for rehabilitation and eventual release.

[edit] References

  • Chiroptera Specialist Group (1996). Pteropus poliocephalus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
  • Eby, P. 2000 The results of four synchronous assessments of relative distribution and abundance of Grey-headed Flying-fox Pteropus poliocephalus. In Proceedings of a Workshop to Assess the Status of the Grey-headed Flying Fox. Hall, L. (Ed.): Australasian Bat Society: Canberra.
  • Hall, L. S. & Richards, G. C. 2000 Flying foxes: fruit and blossom bats of Australia. Sydney: University of New South Wales Press.
  • Menkhorst, P. & Knight, F. 2001. A field guide to the mammals of Australia. South Melbourne: Oxford University Press, x+269 pp. ISBN 0-19-5508703.
  • Nelson, J. E. W. 1965 Behavior of Australian Pteropodidae (Megachiroptera). Animal Behaviour 13, 544-557.
  • Simmons, N.B. 2005. Order Chiroptera. Pp. 312-529 in Wilson, D.E. & Reeder, D.M. (eds.). Mammal species of the world: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp. ISBN 0-8018-8221-4.
  • Tidemann, C. R. 1999 Biology and management of the grey-headed flying-fox, Pteropus poliocephalus. Acta Chiropterologica 1, 151-164.
  • Welbergen, J. A. 2006 Timing of the evening emergence from day roosts of the grey-headed flying fox, Pteropus poliocephalus: the effects of predation risk, foraging needs, and social context. Behavioral Ecology and Sociobiology 60, 311-322.
  • Welbergen, J. A., Klose, S. M., Markus, N. & Eby, P. 2007 Climate change and the effects of temperature extremes on Australian flying-foxes. Proceedings of the Royal Society B, 275,419-425 doi:10.1098/rspb.2007.1385

[edit] External links

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Illustration

Grey-headed flying foxs in the Royal Botanic Gardens, Sydney

Maximum wingspan exceeds 1 metre

17 day old female in care of WIRES

Young female in care of WIRES

Young female playing with her WIRES caretaker

Flying fox in captivity