Daintree Rainforest - Wet Tropics Frogs

(Photo: Mike Trenerry)

As a region known for its extraordinary biodiversity, the species richness of frog species in the Wet Tropics is consistent with other animal groups. However, Australia does not have any representatives of two of the world's three types of amphibians - nor does it have a naturally occurring toad. Amphibians consist of frogs and toads (called anurans), salamanders and caecilians (which resemble worms).

Nationwide, we have at least 212 species of frogs but new ones are awaiting description and perhaps even discovery. About 54 frog species occur in the Wet Tropics region as well as the introduced pest, the Cane Toad (Bufo marinus). Australia lacks salamanders and caecilians.

Amphibians get their name from their unique life cycle where they spend part of their life under water and another part of their life on land. The process by which they change from one type of animal (an aquatic one with gills) to another type (a terrestrial animal with lungs) is called metamorphosis. Children especially have always been fascinated with collecting tadpoles and watching them change into frogs.

In north Queensland, we have a range of frog types including tree frogs, burrowing frogs, water-holding frogs which encase themselves in a 'plastic bag' during the dry season - even frogs which do not have any aquatic tadpoles! Some frogs prefer the cooler climates of the highest mountain tops in the World Heritage Area while others can easily be found in humid lowland habitats such as wetlands, melaleuca (paperbark) swamps, flooded grasslands and cane fields and fast flowing, rocky creeks. Some frogs don't mind suburbia and often take advantage of our use of electricity. You'll find these frogs clinging to illuminated house windows while they lie in wait to ambush insects attracted to the light.

Frogs are a hot topic worldwide as many of them are in the process of becoming extinct. Fortunately, we have some species which are still relatively common and can be easily found in our suburbs or other spots close by. If you want to know what frogs are in your yard, there are two ways to find out. One is to identify the frog by its call and the other is to find the frog and identify it by sight.

A male frog uses a vocal sac to make sounds when he wants to advertise that he's ready to mate. These sounds enable the female to find him when she's ready. (Frog calls create a risk for the male as well because the calls attract the sort of animals that would like to eat the frog such as snakes). Each species has a totally unique call and only the females of that species will respond to it. Even when the calls of two different species sound alike to us, they are actually at slightly different frequencies or pitches. Scientists use electronic testing equipment to create a 'sonogram' of the calls and these sonograms show graphically the minute differences that are too subtle for our ears to distinguish.

If you want to learn the frog calls and identify your backyard frogs yourself, you can buy a frog call tape. It's not hard to learn the frog calls - it's just like learning bird calls - only there are fewer to remember!

Frog calls are a good way to identify the species but it's more fun to look for and find the frogs themselves! They are generally endearing animals which fascinate young and old alike. Some are tree dwellers, others burrow under ground or in leaf litter, some hide under tree bark and others prefer to hang around sedges at the edges of dams - some are as close as your outdoor loo (bathroom) or drainpipe!

Information cortesy of the Wet Tropics Management Authority.