Preliminary observations on a highly-restricted tableland population of Green and Golden Bell frogs on the Upper Molonglo River, NSW

The Green and Golden Bell Frog Litoria aurea disappeared from the Southern Tablelands of New South Wales in the early 1980's and despite many years of opportunistic survey, it was not until 1999 that it was rediscovered near the Upper Molonglo River east of Queanbeyan. The nearest known populations of the species occur at Kioloa, 85 km east of the site. In order to determine the distribution of the population we undertook surveys and monitoring over a two-year period (September 2000 to April 2002) to establish the extent of the population in the region, and to describe the breeding sites that are still occupied. Fieldwork was hampered considerably by extended drought and in some cases by restrictions on access imposed by landholders. All sites surveyed were within 300 m of the Molonglo River. The species was found to occupy 8 of the 10 wetlands (small billabongs) surveyed, 4 of 5 river sites surveyed on the Molonglo River, and at only 1 of 52 farm dams surveyed. It was also heard calling from a small lake on private property. Of the 14 occupied sites surveyed, only three wetland sites supported >10 adult frogs. Additional surveys of the surrounding district, along with a leaflet drop requesting information on any sightings of bell frogs from local landholders, did not reveal any additional populations. Some breeding sites have been affected by cattle grazing and by conversion of native tussock grassland to improved pasture. However, the major threat to this population in the longer term is likely to be the amphibian chytrid fungal pathogen that is present in the population. We speculate that it is possible that the persistence of the species in this area could relate to the historical contamination of the river and floodplain sediments by heavy metals associated with the old mine tailings dam at Captains Flat. It is possible that this pollution has reduced the impact of chytrid on frogs in this region. Management prescriptions, including for livestock activity in and around wetlands, need to be implemented to ensure the ongoing persistence of this important regional population.