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
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.