NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. The Grey-headed Flying-fox occurs primarily along the eastern coastal plain from Bundaberg in Queensland, through NSW and south to eastern Victoria. A colony has also established in Melbourne (FFG SAC 2001). Small numbers may occur as far west as Warrnambool (Menkhorst 1995). Regular movements are made over the Great Dividing Range to the western slopes of NSW and Queensland.
2. This species is a canopy-feeding frugivore, blossom-eater and nectarivore of rainforests, open forests, woodlands, Melaleuca swamps and Banksia woodlands. As such, it plays an important ecosystem function by providing a means of seed dispersal and pollination for many indigenous tree species (Eby 1996; Pallin 2000). Grey-headed Flying-foxes also feed on introduced trees including commercial fruit crops.
3. Grey-headed Flying-foxes are relatively long-lived mammals, with the average age of reproductive animals being between six and 10 years. They have a low rate of recruitment as sexual maturity is reached after at least two to three years and generally only one offspring is produced each year (Martin et al. 1996).
4. Grey-headed Flying-foxes congregate in large numbers at roosting sites (camps) that may be found in rainforest patches, Melaleuca stands, mangroves, riparian woodland or modified vegetation in urban areas. Individuals generally exhibit a high fidelity to traditional camps and return annually to give birth and rear offspring (Lunney and Moon 1997; Augee and Ford 1999). They forage opportunistically, often at distances up to 30 km from camps, and occasionally up to 60-70 km per night, in response to patchy food resources (Augee and Ford 1999; Tidemann 1999).
5. Grey-headed Flying-foxes show a regular pattern of seasonal movement. Much of the population concentrates in May and June in northern NSW and Queensland where animals exploit winter-flowering trees such as Swamp Mahogany Eucalyptus robusta, Forest Red Gum E. tereticornis and Paperbark Melaleuca quinquenervia (Eby et al. 1999; P. Birt and L. Hall, pers. comm.). Food availability, particularly nectar flow from flowering gums, varies between places and from year to year.
6. Historically, Grey-headed Flying-foxes had a greater range in Australia and numbers were estimated as being in the "many millions" (Ratcliffe 1932). Counts of flying foxes over the past decade suggest that the national population may have declined by up to 30% (Birt 2000; Richards 2000). Regular visits to flying-fox camps during this period have shown a marked decline in the numbers of animals using several camps (reductions of 31% to 94% have been recorded at five camps, Eby 2000; Hall 2000; Parry-Jones; P. Eby pers. comm.). It has also been estimated that the population will continue to decrease by at least 20% in the next three generations given the continuation of the current rate of habitat loss and culling (Martin 2000).
7. The main threat to Grey-headed Flying-foxes in NSW is clearing or modification of native vegetation. This removes appropriate camp habitat and limits the availability of natural food resources, particularly winter-spring feeding habitat in north-eastern NSW. The urbanisation of the coastal plains of south-eastern Queensland and northern NSW has seen the removal of annually-reliable winter feeding sites, and this threatening process continues (Catterall et al. 1997; Pressey and Griffith 1992; P. Clarke, unpublished data). In N.S.W less than 15% of potentially suitable forest for the Grey-headed Flying-fox occurs in conservation reserves; only 5% of roost sites are similarly reserved (Hall and Richards 2000).
8. The use of non-destructive deterrents, such as netting and noise generators, to limit flying-fox damage to fruit crops is not universal in the horticultural industry. While licences are issued to cull limited numbers of Grey-headed Flying-foxes, uncontrolled culling using destructive methods such as shooting and electrocution occurs and large numbers of bats are culled (Vardon and Tidemann 1995; Richards 2000). The impact of destructive methods has not been measured but is likely to be greatest in those years when natural food is scarce. Also, culling has a disproportionate impact on lactating and pregnant females (Parry-Jones 1993).
9. The species is also threatened by direct harassment via shooting at roosts, the destruction of camps and by being possible carriers for viral pathogens (Lunney and Moon 1997; Tidemann 1999).
10. Grey-headed Flying-foxes face potential competition and hybridisation from Black Flying-foxes, Pteropus alecto, as this species is extending its range south into northern NSW (Webb and Tidemann 1995). Colonisation of northern NSW may be assisted by the flexible reproduction of P. alecto and dispersal from largely intact northern habitats (Vardon and Tidemann 2000) into more fragmented habitat in the south.
11. In view of the above points, the Scientific Committee is of the opinion that the Grey-headed Flying-fox, Pteropus poliocephalus, is likely to become endangered unless the circumstances and factors threatening its survival or evolutionary development cease to operate, and is therefore eligible for listing as a Vulnerable species.
Proposed Gazettal date: 4/05/01
Exhibition period: 4/05/01 - 8/06/01
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