Threatened Species and threatened ecological communities
Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
Pteropus banakrisi (Torresian Flying-fox).
The Torresian Flying-fox is claimed to be the smallest flying-fox known to occur in Australia. Its scientific description was first published in 2002, however there is still ongoing debate among experts over the recognition of this taxon. It is blackish with relatively long ears and a long thumb. The fur on the belly is often tipped grey. Little is known of its ecology, but its teeth suggest that it is a fruit-eating species.
The Torresian Flying-fox is known to occur on only one island - Moa Island, which lies about midway between Cape York Peninsula and Papua New Guinea in the Torres Strait. Moa Island is distinctive in the region for its large areas of tropical rainforests. The species possibly occurs on other islands in Torres Strait.
The Torresian Flying-fox is currently listed as vulnerable under Queensland threatened species legislation as the species Pteropus sp. nov. (A.N.W.C CM5012; Richards & Hall 1994).
The Torresian Flying-fox was classified as data deficient in the 1999 Bat Action Plan (Duncan et al. 1999). At that time, there was little known about the species and its taxonomic status was unresolved - the possibility existed that it was simply a form of the very similar Black Flying-fox P. alecto, a species that migrates seasonally to Moa Island. In addition, there was no formal published description of the Torresian Flying-fox, but it was considered by some experts to be different from the Black Flying-fox on the basis of morphology - being smaller in many characters, significantly different in cranial characters, and having a different shaped baculum. Other experts considered that individuals that were being categorised as Torresian Flying-foxes were either juvenile or neotenous adult (adults that have retained juvenile characteristics) Black Flying-foxes or were examples of island dwarfism of the Black Flying-fox. Preliminary DNA analysis showed the Torresian Flying-fox had a close affinity to the Black Flying-fox.
Since the publication of the Bat Action Plan, the formal scientific description of the species has been published (Richard & Hall 2002).
TSSC judges the species not to be eligible for listing as endangered under the EPBC Act. The justification against the criteria is as follows:
There is little known about the abundance of the Torresian Flying-fox. Usually, estimates of flying-fox numbers are based on either numbers counted at their colonies or fly-out counts as flying-foxes leave their colonies for night feeding. There are no verified colonies for this species. In 1990, a colony of flying-foxes was located on the north side of Moa Island. Although the identity of the species inhabiting the colony was not certain, it was considered most likely to be Torresian Flying-fox. A survey in difficult conditions estimated that this colony contained less than 1000 individuals. There was possibly a second colony site on nearby Iem Islet that would have accommodated 200 individuals. The nomination estimates the population to be less than 2000 individuals. There is no further information on population size and no indication that a reduction in numbers has occurred.
Therefore, the species is not eligible for listing as under this criterion.
The Torresian Flying-fox is known to occur on only one island - Moa Island, which lies about midway between Cape York Peninsula and Papua New Guinea in the Torres Strait. Moa Island is distinctive in the region for its large areas of tropical rainforests. There are also unverified reports of the Torresian Flying-foxes occurring on a very small islet called Iem Islet. It is possible the species occurs on other islands in the region, though many Torres Strait islands have been surveyed for bats and no Torresian Flying-foxes have been found.
There is very little known about the Torresian Flying-fox. On Moa Island, the only colony where the species is thought to occur is difficult to access and appears to have been only surveyed by air in 1990 under difficult survey conditions. At that time, there was some uncertainty regarding the identity of the species of flying-foxes in the colony, and it appears that the identification of species of flying-foxes in the colony has never been verified. If the Torresian Flying-fox does inhabit the colony, it is thought that it would only forage over the rainforest areas of Moa Island, which cover an area of about 20-30 km2.
No threatening processes, other than the possibility of cyclones, have been clearly identified for the Torresian Flying-fox. In 1990, it was considered that this flying-fox was reasonably well protected by the remoteness of its distribution, by the current awareness of the indigenous community resident on Moa Island, and by the presence of crocodiles at the colony site that would restrict human access and human predation. At that time, predation by humans was not considered to be a threat to this flying-fox. If the Torresian Flying-fox is truly restricted to a single colony, stochastic events, such as cyclones, could be a threat to the species.
There is insufficient information to assess whether the Torresian Flying-fox has a restricted or limited geographic distribution that is precarious for the survival of the species. Therefore, the species is not eligible for listing under this criterion.
There is little known about the abundance of the Torresian Flying-fox. Usually, estimates of flying-fox numbers are based on either numbers counted at their colonies or fly-out counts as flying-foxes leave their colonies for night feeding. There are no verified colonies for this species. In 1990, a colony of flying-foxes was located on the north side of Moa Island. Although the identity of the species inhabiting the colony was not certain, it was considered most likely to be the Torresian Flying-fox. A survey in difficult conditions estimated that this colony contained less than 1000 individuals. There was possibly a second colony site on nearby Iem Islet that would have accommodated 200 individuals. The nomination estimates the population to be less than 2000 individuals. There is no further information on population size and, currently, no indication that a reduction in numbers or distribution has occurred.
Therefore, the species is not eligible for listing as under this criterion.
There is little known about the abundance of the Torresian Flying-fox, see Criterion 3.
Therefore, the species is not eligible for listing as under this criterion.
There is no quantitative data available against this criterion.
Therefore, the species is not eligible for listing under this criterion.
Little is known about the Torresian Flying-fox, and there appear to be few verified sightings in the wild. It is known to occur on Moa Island in the Torres Strait, but there are no verified colonies of this species and it may be more widely spread. Its population numbers are not known. There appear to be no known threatening processes impacting on the Torresian Flying-fox, though cyclones may threaten the species if its distribution is found to be truly restricted. It is considered that there is insufficient information at this time to determine the conservation status of the Torresian Flying-fox.
The TCCS conclude that the evidence available does not establish that the Torresian Flying-fox meets the eligibility criteria for listing as threatened.
TSSC recommends that Pteropus banakrisi (Torresian Flying-fox) is not eligible for inclusion in the list referred to in section 178 of the EPBC Act.
Duncan, A., G.B. Baker & N. Montgomery. 1999. The Action Plan for Australian Bats. Environment Australia, Canberra.
Hall, L., & G. Richards. 2000. Flying Foxes - Fruit and Blossom Bats of Australia. Univ. NSW, Sydney.
Richards, G.C. 1990. The Conservation Status of the Torresian Flying Fox. Unpubl. report to the Endangered Species Advisory Committee, Aust. NPWS.
Richards, G.D. 1995. Torresian Flying-fox Pteropus sp. In Strahan, R. (ed). The Mammals of Australia. Aust. Museum, Reed Books.
Richards, G.C & L.S. Hall. 2002. A new flying-fox of the genus Pteropus (Chiroptera: Pteropodidae) from Torres Strait, Australia. Aust. Zool. 32: 69-75.