Green and Golden Bell Frog

A combination of pressures acting together caused a species that was once extremely common across coastal southeastern Australia to vanish from around 90 percent of its historic range within a few decades. The single most damaging factor is generally considered to be the amphibian chytrid fungus, a disease that spread through Australian frog populations from the late 20th century and that attacks the skin frogs depend on for breathing and regulating water and salt balance. On top of this, extensive draining and filling of coastal wetlands removed breeding habitat, and the introduction of predatory fish such as the eastern mosquitofish into remaining ponds greatly increased mortality of eggs and tadpoles.

It initially seems paradoxical that a threatened frog does best in degraded, human-made landscapes, but several features of these sites appear to work in the frog's favour. Disused brick pits, quarries, and constructed ponds are often newly created water bodies that predatory fish have not yet colonised, they frequently have hard, bare, sun-exposed banks and shallow warm water rather than shaded forest streams, and the warmer, sunnier conditions may suppress the chytrid fungus, which does poorly at higher temperatures, and give the frogs, which bask heavily, a way to raise their body temperature and fight infection. As a result, some of the largest surviving populations are in exactly the kind of sites conservationists once would have overlooked.

Most frogs avoid prolonged sun exposure because their permeable skin loses water quickly, but the green and golden bell frog regularly spends long periods sitting fully exposed on rocks, logs, reeds, and pond edges in bright sunshine. This basking behaviour raises the frog's body temperature well above that of a shaded frog, which speeds digestion and growth, and researchers believe it also serves as a defence against the chytrid fungus, since the fungus cannot tolerate the elevated skin temperatures that a basking frog can reach and sustain, effectively allowing the frog to bake off or hold back an infection.

Yes. Although it is no longer as close to complete collapse as it appeared in the 1990s, and a number of populations are now stable or actively managed and protected, the species remains classified as Vulnerable with an overall declining trend. Its surviving populations are small, scattered, and often isolated from one another, which makes them vulnerable to local extinction from disease outbreaks, drought, pollution, or development, with little chance of natural recolonisation. Conservation efforts focus on protecting and creating suitable fish-free, sunny water bodies, managing the chytrid threat, and in some cases captive breeding and reintroduction.