Catastrophic declines of Australian rainforest frogs: Is unusual weather responsible? Original Research Article

In the montane rainforests of eastern Australia, at least 14 species of frogs that breed in, and live near, streams have declined dramatically during the past 15 years. I explored the hypothesis that atypical weather was wholly or partly responsible for these declines, using a computerized weather analysis package and data on 10 rainfall and temperature parameters gathered from 17 strategically located weather stations. Most weather stations exhibited a moderate (≤25%) reduction in annual rainfall in the five years immediately preceding frog declines, usually due to a decline in wet season rainfall, and within-year rainfall variability declined consistently. During the same period nearly half of all stations exhibited a significant increase in the frequency of ‘major drought’ months. There also was an excessive number of months with atypically high average temperatures, especially in summer, although other temperature parameters did not deviate significantly from long-term weather averages. In general, however, the moderate deviations of rainfall and temperature measures from long-term averages at each site appear to be an inadequate explanation for the dramatic declines of montane frogs in Queensland. Other possible factors, especially epidemic disease, should be explored in further detail.