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Widespread, Noisy, Amphibians… Australian Frogs

By Keith Hutton on January 26, 2016 in Other

Photo: Dan Hutton

Photo: Dan Hutton

Australia is recognised worldwide for its amazing and unique wildlife, and Sydney remains a haven for a wide variety of species. Randwick and Waverley Councils are aware of the significance of this. In the suburbs east of the city, birds are obvious; mammals, reptiles, spiders and insects often attract attention, and frogs are widespread. All these creatures are included in adaptive environmental management planning, and monitored periodically by local councils. Frogs in the east are the least well known, unlike their relatives in the west, Green and Golden Bell Frogs, which really hit the headlines when they were discovered in Olympic Park at the time of the Sydney Olympic Games. Unfortunately frogs sporting our national colours no longer appear to be present in the Eastern Suburbs.

Adult frogs are generally nocturnal; they have four limbs but no tails, and cold damp skin that may be smooth or rough. They lay eggs that usually develop independently into tadpoles, and then metamorphose into frogs. Most Australian frogs are either tree frogs or ground frogs. Tree frogs have enlarged toe discs and are often brighter coloured than ground frogs; many are green, and spend much time off the ground in trees and other plants. Ground frogs have more slender digits, and smaller toe and finger discs. Both types occur in the Eastern Suburbs.
There are about 240 Australian frog species, with 50 or so in the Sydney region. Frogs are found almost anywhere in the country in urban, rural and bushland situations. As a group they require water to breed and to avoid desiccation, and the best places to find them are suitable breeding sites like ponds, streams and other damp and wet areas, particularly after rain. They can be heard calling, and found at the water’s edge in nearby vegetation, or under rocks and other cover.

Adults are opportunistic predators and eat a variety of live food. Big frogs eat larger prey such as other frogs, small mammals and reptiles, while small frogs eat mostly insects, spiders and worms. They grab prey with a sticky tongue then, with the help of both hands, manipulate it before gulping it down. Tadpoles initially eat plant material, and increase protein intake with animal food as they mature.

Australian frogs, like many around the world, are affected by a variety of things the lead to a decline in a number of species. The main factors are disease, habitat destruction, pollution, increased ultraviolet-B radiation and global climate change. In Australia, predation by exotic fish, increased salinity, and introduced Cane Toads are recognised threats. Locally endangered Green and Golden Bell Frogs have been lost from Malabar Headland within living memory. However, Eastern Dwarf Tree Frogs have established themselves there since 1995, and these pretty little frogs remain common, and of least conservation concern in the Sydney region: they are easy to see in the gardens at Randwick Environment Park. Clearly further research is required to improve understanding of frog populations, and positive action may help to slow the loss of frogs worldwide.