Western Banjo Frog

Limnodynastes dorsalis (Gray 1841)

Species Info Card | Updated 1 decade ago

A large robust ground-dwelling frog, up to 7.5 cm. The back is grey or dark green with numerous, irregular dark brown blotches and a thin pale yellow line running along the centre of the back from nose to rump (where the specific name dorsalis comes from). Bright orange to red patches are present in the groin. Other distinguishing features are a glandular ridge at the corner of the mouth and large glands on the upper side of the calves. Male Western Banjo Frogs have thicker, more powerful arms than females and develop a dark throat as well as nuptial pads during the breeding season.

Breeding Biology

A winter and spring breeder. Calling begins as early as May in the northern part of the range, and from July-August around Perth. Breeding continues through to early December.

During mating, the female beats the surface of the water to produce a white foamy mass. The eggs are laid into the base of this foam 'raft' which is usually hidden beneath overhanging vegetation. The foam nest floating in open water is unique among south-western frogs (although several species have foam nests but concealed in burrows).

Tadpoles are relatively large, growing up to 8 cm in length. The back is dark brown, almost black, sometimes with scattered black spots, while the underneath is dark with a blue hue. Tail fins are high, and lack pigment. Tadpoles are usually found in deep, permanent water, and may be present all year round, as development can be slow. Tadpoles metamorphose into froglets from early summer to April.

Habitat

Permanent and temporary water including farm dams, swamps, wetlands and streams.

Etymology

dorsalis likely refers to the back pattern of this species.

General

Adult and juvenile Western Banjo Frogs are often encountered a considerable distance from permanent water. They are adept at burrowing and spend much of the year buried in sandy soils away from breeding sites.

Found over a large area of the south-west from Kalbarri, throughout the wheatbelt and south-west forests and east to Cape Arid. In the metropolitan region they are most abundant in coastal plain wetlands.

A single, explosive 'bonk' repeated at intervals and answered by other males. Males call from dense overhanging vegetation such as grass and sedges around the water's edge. Calls can be heard from a considerable distance.