The Action Plan for Australian Frogs
By
Michael J. Tyler
with the assistance of the Editorial Advisory Committee
Wildlife Australia, April 1997
ISBN 0 642 21400 X
Recovery Outline No. 1: Green and Golden Bell Frog
1. Family
Hylidae
2. Scientific Name
Litoria aurea
3. English Name
Green and Golden Bell Frog
4. Intraspecific taxa:
None
5. Species survival status
Endangered. (Extinct in the ACT except Jervis Bay National Park, endangered in NSW but apparently secure in eastern Victoria). There are numerous reports of decline in NSW and the ACT. Interpretation is complicated by confusion of identification between this species and the closely-related L. raniformis. Morphological differences between these two taxa can be subtle and variable, and are often obscured or lost in preserved museum specimens. Further, Sherwin (1978 unpublished in Gillespie 1996) points out that there is a contact zone between the two species in eastern Victoria in which intermediate forms (hybrids?) occur. Consequently public reports of declines of "Bell Frogs" may refer to either of these species or to
L. castanea. If the decline of L. aurea is to be accurately documented, the geographic limits for both species need to be clearly defined, through a more careful examination of museum specimens and a genetic study of the remaining populations. Nevertheless, the species is estimated to have disappeared from 90% of its former range in NSW, and appears to have disappeared entirely from all non-coastal sites.
6. Former distribution
North coastal NSW to eastern Victoria (south of the Great Dividing Range) including the Hunter Valley, southern highlands and Monaro districts of NSW and the ACT.
7. Current distribution
The species has almost entirely disappeared from the southern highlands and southern slopes and the ACT, and has a patchy distribution along the NSW coast. White and Pyke (1996) list 21 known occupied sites outside and 21 within the Greater Sydney Region (post 1990). The species is apparently secure in Victoria and has an almost continuous distribution along eastern Victoria (south of the Great Dividing Range) down to the Gippsland Lakes district.
8. Habitat
The species appears to have originally been associated with semi-permanent or permanent water including marshes, dams and stream-sides. These waterways frequently contained bullrushes (Typha sp.) or spikerushes (Eleocharis sp.). Bell frogs seem to have disappeared from many of these habitats in NSW, and, in the Greater Sydney Region, are most frequently found in disturbed sites, often extremely so, such as disused industrial sites, brick pits, mines, recently cleared bushland or council tips.
9. Reasons for decline
Various reasons are apparent including destruction of wetland areas. A summary of existing knowledge of the declines and general biology and ecology of the species can be found in Pyke and Osborne (1996). There is also a growing amount of indirect and direct (Morgan and Buttemer 1996) evidence that the introduced mosquito fish (Gambusia holbrooki) is a predator of the eggs and tadpoles of these frogs. As the fish has become widespread throughout the waterways of NSW there has been a corresponding decline in Bell Frogs in these areas. Gambusia is spreading down the NSW coast towards the Victorian border and the impact of this species on the Victorian population of Bell Frogs needs to be monitored.
10. Conservation reserves on which species occurs
NSW: Yuraygir, Botany Bay, and Seven Mile Beach National Parks, Nadgee Nature Reserve; ACT: Jervis Bay National Park; Vic: Croajingalong and Cupracambra National Parks, Ewings Marsh Flora Reserve, Cape Conran State Park.
11. Other public lands on which species occurs
NSW: Cox's Creek Reserve, Greenacre, Eastlakes, Kogarah, New Brighton, and East Hills Golf Courses, Lake Woolumboola Foreshore, Lt. Cantello Reserve, McGuire's Crossing, Meroo Lake Foreshore, Beecroft Peninsula, Termeil State Forest; Vic: State Forests in East Gippsland (unnamed).
12. Other lands on which species occurs
Various industrial sites in Sydney Metropolitan Area such as Homebush Bay Brick Pit, Rosebery State Super Site, Newington Armaments Depot, Enfield Railway Yards and Brick Pit at Strathfield and several sites on the Kurnell Peninsula. All other sites are on private land around Sydney. Occurs near pasture land around Shoalhaven River.
13. Is knowledge about species adequate for objectives and actions to be defined accurately?
No. Previously it had been assumed that the ecological requirements of L. aurea would be similar to those of L. raniformis. The apparent ability of L. aurea to colonise, or at least persist, in highly disturbed sites unlike its traditional habitat (and its disappearance from localities where there is no apparent cause) makes comparisons with closely related species more difficult to interpret. L. raniformis is also able to persist in highly disturbed sites, for example, several populations occur in industrial areas of metropolitan Melbourne (G. Gillespie pers. comm.).
14. Recovery Plan objectives
14.1. To determine the current status of the species.
14.2. To recommend actions that may halt the declines and aid the recovery of the species.
15. Management actions completed or under way
15.1. A management plan is being prepared for translocation of L. aurea from the Rosebery site.
15.2. An intensive study of the Homebush Bay populations undertaken by G. Pyke and A. White has the long-term aim of habitat restoration and species reintroduction into areas it previously occupied.
15.3. A preliminary captive management and frog breeding program has been successfully conducted by Taronga Zoological Park in Sydney.
15.4. Species profiles and draft species management prescriptions have been jointly prepared by State Forests of NSW and NSW National Parks and Wildlife Service for protection of this species within production forest.
16. Management actions required
16.1. Establish base data on NSW/Victorian border populations prior to the entry of the Mosquito fish Gambusia holbrooki into this area.
16.2. Determine the impact of Gambusia on tadpoles and eggs.
16.3. Determine the ecological requirements for sustaining viable populations in the wild.
16.4. Seek the cooperation of amateur herpetological groups to determine the species' existing geographic range and the status of identified populations. State wildlife agencies could coordinate such surveys. The Frog and Tadpole Study Group of NSW Inc. have been extensively involved in survey activities for endangered frogs, with many of the sites listed in 11 and 12 being found and monitored by them.
17. Organisations responsible for conservation of species
NSW National Parks and Wildlife Service, Vic. Department of Natural Resources and Environment, ACT Parks and Conservation Service.
18. Other organisations involved
Department of Defence (in relation to Beecroft Peninsula), Frog and Tadpole Study Group of NSW Inc., University of Newcastle, G. Pyke and A. White, Taronga Zoological Park, State Forests of NSW.
19. Can recovery be carried out with existing resources?
No.
Work required needs to be spread across several State organisations. Museum study to clarify information on former distribution $2K; field studies in the ACT, eastern Victoria (south of the Great Dividing Range), southern NSW, central coastal NSW and northern coastal NSW ($20K each location).
Total $102K
References:
Gillespie, G. R. 1996. Distribution, habitat and conservation status of the Green and Golden Bell Frog Litoria aurea (Lesson 1829) (Anura: Hylidae) in Victoria. Australian Zoologist 30(2): 199-207.
Morgan, L. A. and Buttemer, W. 1996. Predation by the non-native fish Gambusia holbrooki on small Litoria aurea and L. dentata tadpoles. Australian Zoologist 30(2): 143-149.
Pyke, G. H. and Osborne, W. S. (eds) 1996. The Green and Golden Bell Frog Litoria aurea : Biology and Conservation. Australian Zoologist 30(2): 130-258.
White, A. W. and Pyke, G. H. 1996. Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales. Australian Zoologist 30(2): 177-189.
Herpetological authorities consulted
H.G. Cogger, H. Ehmann, G.R. Gillespie, R. Jenkins, M.J Littlejohn, L.C. Llewellyn, M.J. Mahony,
W.S. Osborne, A.W. White.