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Green Tree Frog
(Litoria caerulea)

By Alicia Carter

Most of us are familiar with this delightful resident, but maybe not aware of its decline in numbers throughout the region in recent years. This was to be expected given the increase in cane toads regionally as well as the continued clearing for housing and farm development.

The Green Tree Frog is very bright green with a few white specks on its sides, having a white belly and thick skin folds over its eardrums. It has four long, one third webbed, fingers on its arms and five long, three quarter webbed toes on its legs, with large adhesive discs at the end of each toe and finger that enables it to climb.

This species is classed as an ectothermic vertebrate, meaning they are cold blooded, relying on the outside temperature to maintain body heat, and have a backbone, which is typical of all amphibians. It lays eggs in water that hatch into gilled tadpoles, which later develop legs and lungs and emerge onto land. Most species of frogs require damp conditions or water to breed, and have gills in the larval stage. As adults they breathe air through their lungs, but the skin is also an organ of respiration, used to take in oxygen and eliminate carbon dioxide, this is called cutaneous respiration.

This Green Tree frog makes a deep “crawk…crawk… crawk” sound which you may hear coming from inside your drain pipes, water tanks and hollow branches. It will often hang about around outside lights, catching insects that fly past, a very valuable reason to promote frog habitat in your garden.

You are most likely to see frogs after rain and they can be found around the waters edge or in nearby long grass, under rocks logs or under leaf litter. It is often easier to find frogs at night as you can hear their distinctive mating calls of which I am sure you are all familiar. The chorus that you hear at night is an indication of the health of you local water supply. You can often see foam egg masses in the water edges which are native frog spawn. The cane toad eggs float in spaghetti like strings and it is advisable to remove such clusters if you are certain that these are cane toad eggs.

Only the tree dwelling frogs are bright green, the function of this colour is camouflage, in some instances, however, the colour is to make it so conspicuous, that certain predator animals will assume that it would not be palatable. Most frogs are able to darken or lighten their colour's to match their surroundings, by contracting or expanding the various pigment cells in their skin.

Other tree dwelling species that occur in this area are: the Red-eyed Green Tree Frog, with its distinctive red eyes and smaller body size, the Green Leaf Tree Frog, which is much lighter in colour and the Dainty Tree Frog which you will often find on the underside of banana leaves.

Frogs have been around for at least 180 million years and are a valuable nutrient in the food chain as well as an indicator as to the water quality. Scientists all over the world have noted the decline in frog population which they thought was mainly due to human impact on the landscape. They have also found decline in frog populations in relatively pristine environments, which is why frog conservation groups are busily taking note of the frogs of the world. One third of Australia’s frog species occur in our dwindling rainforests, and there are most likely many not yet described.

We can help increase frog populations by not draining breeding sites of water, not introducing new fish species to fish ponds and in fact changing a fish pond into a frog pond. It is also crucial that we ceasing the use of poisons around frog breeding areas. If you notice pools of water drying up that have tadpoles in them you can gently scoop them up with a kitchen drainer and place the eggs in a more suitable body of water near the vegetation on the edge of a creek or dam.
Frogs are preyed upon by all sorts of creatures, wading birds stalk the shallows of water courses, diving birds, fish, freshwater tortoises, larger frogs and of course snakes. The poor frogs are even eaten by aquatic insects in the tadpole stage, one wonders how they manage to survive at all being such tasty morsels, soft and with little or no protection at all.

Images by Alicia Carter & Lib Ruytenberg

Updated January 11, 2017  

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