NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. The Alpine Tree Frog Litoria verreauxii alpina (Fry 1915), is a sub-species of the broadly distributed Whistling Tree Frog L. verreauxii. Litoria verreauxii alpina is distinguished from L. v. verreauxii by the presence of dorsal green or olive markings, extensive dorsal warting, and by its greater size. The Alpine Tree Frog is listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
2. The Alpine Tree Frog is the only tree frog known to occur above the winter snowline on mainland Australia. Formerly, the sub-species occurred throughout the alpine and sub-alpine high-country of NSW and Victoria (Green and Osborne 1994), where it was known to utilise a large variety of habitats for breeding, including bog pools, wet grassland, fens, streamside pools and artificial dams (Hunter et al. 1997).
3. During spring and summer of 1996 to 1997, surveys were undertaken that targeted historical Alpine Tree Frog locations in the Bimberi Range and Snowy Mountains, as well as sites in Victoria on the Buffalo Plateau, Bogong High Plains and Davies Plain (Hunter et al. 1997, Osborne et al. 1999). These surveys demonstrated that the Alpine Tree Frog had undergone a dramatic decline throughout its range, had apparently disappeared from the alpine zone and was extremely rare in sub-alpine areas.
4. In NSW, the Alpine Tree Frog is currently known from two man-made ponds and five natural ponds, all within Kosciuszko National Park. Alpine Tree Frogs were last recorded at an alpine site in 1998 through identification of two calling males, although subsequent investigations have not been able to relocate the sub-species at this site (D. Hunter, W. Osborne and K. Green, pers. comm.).
5. As for many Australian frog species, a strong altitudinal relationship is evident in the decline of the Alpine Tree Frog. Increased exposure to ultra-violet (UV) radiation at high altitude, resulting from atmospheric ozone depletion, has been implicated as a likely contributing factor. The Alpine Tree Frog appears to be more susceptible to UV radiation than the sympatric Common Eastern Froglet, Crinia signifera (Broomhall 1997). Species-specific differences in the impact of exposure to UV radiation on hatching success and development have also been demonstrated in North American amphibians (Blaustein et al. 1995).
6. Stochastic events may lead to the extinction of the Alpine Tree Frog at the seven remaining breeding locations. The two man-made ponds are susceptible to pollution by run-off from nearby busy roads. The five natural ponds are subject to drying during drought years. Moreover, all breeding locations are vulnerable to trampling by feral horses and livestock.
7. In view of the above points, the Scientific Committee is of the opinion that the Alpine Tree Frog Litoria verreauxii alpina, is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.
Proposed Gazettal date: 15/03/02
Exhibition period: 15/03/02 - 19/04/02
References:
Blaustein, A.R., Edmond, B., Kiesecker, J.M., Beatty, J.J. and Hokit, D.G. (1995). Ambient ultraviolet radiation causes mortality in salamander eggs. Ecological Applications 5, 740-743.
Broomhall, S.D. (1997). Comparative effects of ultraviolet-b (UV-B) radiation on two sympatric species of Australian anurans, Litoria verreauxii alpina and Crinia signifera. Hon. Thesis, University of Canberra, Canberra.
Green, K. Osborne, W.S. (1994). 'Wildlife of the Australian Snow Country'. (Reed: Chatswood, New South Wales.)
Hunter, D., Osborne, W.S. and Smith, M.J. (1997). Distribution and Abundance of the Alpine Tree Frog (Litoria verreauxii alpina) in the Australian Alps National Parks: Report on the First Seasons Survey (1996-97). (New South Wales National Parks and Wildlife Service: Hurstville.)
Osborne, W.S., Hunter, D. and Hollis, G. (1999). Population declines and range contraction in Australian alpine frogs. In 'Declines and Disappearances of Australian Frogs'. (Ed. A. Campbell.) pp. 145-157. (Environment Australia: Canberra.)