Rainforest frogs of the Australian Wet Tropics: guild classification and the ecological similarity of declining species

Rainforest frogs are classified into nine ecological guilds based on features of reproduction, habitat use, temporal activity, microhabitat and body size. The largest ecological differences are between the microhylid frogs and the rest of the frog species. Within the non-microhylids, there are two primary groups consisting of (i) regionally endemic rainforest specialists, and (ii) a more ecologically diverse group of species that are less specialized in their habitat requirements. Most of the regionally endemic rainforest specialists, which includes species in three ecological guilds, have declined or gone missing in recent years. Multivariate analyses of the ecological characteristics of these species show that it is not a single characteristic that isolates those species that have declined from those which have not. The guilds that have undergone significant population declines in the Wet Tropics are all characterized by the combination of low fecundity, a high degree of habitat specialization and reproduction in flowing streams. These results have important implications for the determination of the causal factors in the unexplained global decline of many amphibian species.