Forest Frogs

Skyrail Nature Diary: May 2007

Despite accounting for only 0.01% of Australia's landmass, Australia's Tropical Rainforests support a quarter of the country's 212 frog species, many of which are not found anywhere else.

From the ubiquitous White-lipped Treefrog, to the beautiful Orange-thighed Treefrog and the elusive Northern Barred Frog, representatives from all five of Australia's frog families occur in Australia's Tropical Rainforests.

One of the most commonly sighted frogs is the White-lipped Treefrog (Litoria infrarenata), which reaches over 130mm in length and is easily identified with its green body, white bottom lip and almost glowing white underbelly.

Found throughout North Queensland and Papua New Guinea, the White-lipped Treefrog is also known to be a frequent visitor to window sills and toilet seats in suburbia, only fully retreating to the rainforest during especially dry periods.

The mating calls of many frogs feature subtle differences, undistinguishable to the human ear. However, this is not the case with the White-lipped Treefrog, whose distinctive call can sometimes be mistaken for a dog's bark!

When hiking near rainforest watercourses during summer, you’re likely to hear the mating call of the endemic Northern Barred Frog (Mixophyes schevilli). Spending most of its time on the rainforest floor or in forest streams, the Northern Barred Frog’s skin is light brown in colour, with dark spots helping to provide camouflage from predators.

This frog can reach up to 110mm in length, but it is the tadpoles of this species that are most impressive; some reaching up to 150mm in length (including the tail). It’s little wonder that these tadpoles take two years to reach maturity as a frog, making them Australia's biggest and longest-living tadpoles.

While most frogs are more likely to be heard than seen in Australia’s Tropical Rainforests, the smaller Orange-thighed Treefrog (Litoria xanthomera) puts on an impressive visual display, for those lucky enough to spot it. In addition to its bright red-orange eyes and deep orange flanks and lower limbs, this frog’s yellow vocal sac inflates when making mating calls, creating a characteristic noisy chorus used to attract potential mates.

Restricted to Australia’s Tropical Rainforests, the Orange-thighed Treefrog was previously known as the Red-eyed Treefrog, and was thought to survive as far south as central New South Wales. However, scientists discovered that the population found in North Queensland was a separate species, and reclassified it as such in 1986.