The Grange - Fauna (Frogs)

The Grange Fauna Frogs

Frogs Calling in The Grange

Frogs are the only amphibians native to Australia; elsewhere there are toads, newts and salamandas. The amphibian species known in The Grange are the Striped Marsh Frog, Common Eastern Froglet, Southern-brown Tree-Frog, and the Pobblebonk (Banjo) Frog.

Abundance

The abundance of frog species in Australia has fallen dramatically since European settlement. One of the reasons for their decline is the loss of habitat through the clearing and draining of swamplands. This is because many frogs, as tadpoles, need permanent to semi-permanent water. Marshy places provide them with food such as insects, and shelter from predators.

Habitat

The Grange, especially The Swampy heath community, provides frogs with an environment to live in and grow. During the wetter months and years, this part of The Grange becomes inundated, allowing frogs to breed. The old sand quarry next to, and visible from, the reserve is filled with water all year round, and also provides frog habitat. Frogs are secretive by nature, as they need to hide from their natural predators such as birds and snakes. Frogs are most obvious after rain, and at night when their calls can be heard. This is how male frogs communicate with female frogs during their breeding season.

Life Cycle

The Amphibian nature of frogs means that they have two distinct stages in their lifecycle. One is in water, the other on land.

Water Stage

Most frogs spawn in water, but some spawn on the ground. During mating the male clasps onto the back of the female. He fertilises the eggs as she lays them. These eggs are protected from physical damage or drying out, by a jelly like substance. Usually tadpoles hatch after a few days, but some eggs, which have been laid on the ground, need to be inundated with water, in order to hatch. Tadpoles have gills and feed mostly on algae and rotting plants. This stage of development can last a few weeks or sometimes months. As tadpoles grow, their heads become more distinct from their tails. Then they form limbs and lungs, Eventually tadpoles absorb their tails and become young frogs, sometimes known as metamorphlings.

Land Stage

These metamorphlings can look quite different to adult frogs. They shed their skin, lose their tail stumps and change into frogs. Frogs eat living insects and other invertebrates, and rely on their keen eyesight to catch them. They have sensitive skin, covered in glands, which help to keep it moist. Frogs can breathe through their skin, as well as their lungs.

Different Families

There are just over thirty species of frogs found in Victoria. In general, frogs are hard to find and some are difficult to tell apart. One of the best ways to distinguish frogs is by their call.

The Frog species found in The Grange belong to the two different families found in Victoria: Hylidae and Leptodactylidae.

Hylidae Family

Hylidae is the family of Tree Frogs, although not all Tree Frogs live in trees. They are characterised by their padded toes. Most Tree Frogs eat insects and spiders. Tree Frog species are found across the world. The Grange has one Tree frog, the Southern Brown Tree Frog (Litoria ewingi).

Southern Brown
Tree Frog
Note the pads on its toes

Southern Brown Tree Frog

The Southern Brown Tree Frog (Litoria ewingi) can jump and climb skillfully. It shelters in damp vegetation in The Grange, not just trees. This frog has a distinctive call of rapid and successive “reep reep reep”. It is a small brown to green frog with dark flecks, about 3.5cm long, with the characteristic tree-frog padded toes. It can breed during most times of the year, but it needs water to spawn.

Leptodactylidae Family

The remaining three frog species known in The Grange belong to the Southern Frog family: Leptodactylidae. This is a diverse family, and the frogs belonging to it are usually called lepodactylids.

Eastern Banjo Frog

The call of the Pobblebonk Frog (Limnodynastes dumerili) has a distinctive call like the a banjo string being plucked (bonk bonk), which can be heard at The Grange. The adult is brown to grey in colour, growing up to 7cm in length. It lives in areas permanently inundated with water and eats insects.

Eastern Banjo Frog
(Limnodynastes dumerili)

Striped Marsh Frog	The Striped Marsh Frog This frog, (Limnodynastes peronfl) has dark stripes and spots on a brown body. It grows to about 6.5cm in length and fives in swamps as well as permanent water, where it feeds on small insects. These frogs' calls that sound like a chicken clucking (cluck) can be heard all year round.
The Common Eastern Froglet The Common Eastern Froglet (Ranidelia signifera) is found across most of the state of Victoria. It lives on land, but needs water to breed. The markings on its back can vary so it is best distinguished by the male's cricket-like call of “crick crick crick”.	Common Eastern Froglet