The Herpetological Journal

pp.175-186

Authors: Jean-marc Hero And Clare Morrison

Abstract: Amphibian declines have been reported from around the world. H ere we examine life history and distributional characteristics of Australian frogs listed as threatened under the IUCN Global Amphibian Assessment guidelines, and compare these results to available information on threatened amphibians around the world. Forty of 213 Australian frog species (18.8%) are currently recognised as threatened. While eight species are listed as Vulnerable due to small or restricted populations alone (VU D2), the remaining 32 species are associated with population declines. Threatened species are concentrated in upland areas (41% of all upland species are threatened, while only 8% of lowland species are threatened). Twenty-eight of the 40 threatened species (70%) primarily occur in upland areas while only 42 of the 1 73 non-threatened species (24.3%) occur in upland areas. Restricted geographic range is characteristic of 31 of 40 threatened/declining species (77.5%). However, 41 non-threatened species (23.7%) also have restricted geographic ranges. Latitudinal position is not strongly associated with the degree of threat. Threatened species are strongly associated with specific reproductive habitats: 80% of species occurring in montane wetlands and 58% of species breeding in wet forest streams are threatened. For 22 of the 40 (55%) threatened species, known threats do not adequately explain the extent of decline. Habitat modification is the foremost threatening process associated with declines in 20 of the 40 threatened species (50%), including 11 of 12 threatened lowland species (91.7%). Chytrid fungus is notably associated with declines for five species and a potential contributor for an additional nine species (35% of threatened species). However, the chytrid has also been detected in an additional 33 non-threatened species (19%). Minor threats associated with threatened species include fire and global changes in weather patterns. Phylogenetic relationships of Australian frogs are poorly resolved, and there are no strong associations between phylogeny and declines within knovn1 taxonomic groups. A notable exception are frogs of the myobatrachid genus Taudactylus where five of the six species are threatened. Global patterns are difficult to assess, however, as declines are strongly associated with species that are primarily distributed in upland areas. Chytrid fungus has been found in both declining and non-declining species throughout Australia, and while its role as an emerging infectious disease is currently under investigation (in Australia, New Zealand, Spain, South Africa, Costa Rica, Ecuador and the USA), little is known about its distribution and prevalence in other countries.

Keywords: altitude, amphibians, geographic range, IUCN, life history, status