Tell me about frog calls - why do frogs call?

In most frogs, males signal to females that they want to mate; - this is the famous frog call.

Most people think of the cliched ‘croak’, but in the Australian tropical rainforest there is a wonderful variety of low croaks, wails, chirps and whistles.

These calls are specific to each species.

They allow for species identification and location, (both for the female frog and the herpetologist!)

Many frogs have evolved large vocal sacs that are blown up when calling (pictured).

Others may take advantage of the acoustics within piles of rocks or pipes to amplify their call; many of the more common, well adapted urban frogs (such as the Green Tree Frog and the Red Tree Frog) do this.

Often, many individual males will call from the same area, their combined calling perhaps attracting females from some distance.

While rain is often associated with these calls, the exact cues of many species to call are complex, and may be a combination of factors such as rainfall, temperature, humidity and social signals.

These calls can be recorded and displayed as an oscillogram, which displays signal amplitude in volts/millivolts, or a sonogram, which display frequency (pitch).

The female frog often has hearing which is tuned into the frequencies of which the male of its own species calls, eliminating confusion with all the other frog calls.

For more about the frog life cycle

For much more about frogs and the different species of the Australian tropical rainforest, refer to the book: "Ecosystem Guides: Rainforest of tropical Australia"