Northern Dwarf Tree Frog

The Northern Dwarf Tree Frog, (Litoria bicolor) is a small species of tree frog native to northern Australia, from the Kimberly region of Western Australia to Bowen, Queensland and Aru Islands of Indonesia. The population occurring in Indonesia may not be Litoria bicolor and research on call structure or genetics is needed to confirm its taxonomic status.

Physical Description

The Northern Dwarf Tree Frog is small slender tree frog growing up to 30 mm in length. The dorsal surface is green and is bordered by a bronze stripe that runs along the flanks, from the shoulder to the groin. There is a white stripe that runs along the upper lip to the base of the arm and may continue on to the groin. The belly is granular and white or pale yellow. The iris is golden and the tympanum is distinct. There is orange in the groin and thigh. The fingers have a trace of webbing and the toes are half to three-quarters webbed.

Ecology & Behaviour

Most abundant in grassland or marshy areas, but also occurs along permanent or semi-permanent streams, billabongs and floodplains. Breeding starts with summer rains and 10-20 eggs are laid on submerged vegetation in temporary pools. Males call from around the breeding site from elevated positions. The call is a "wree-e-eck pippip" with the second part of the call starting before the first part finishes. Tadpole metamorphosis takes 70 to 80 days.

Similar species

The Northern Dwarf Tree Frog is a member of the Litoria fallax complex, which includes also includes the Eastern Dwarf Tree Frog (Litoria fallax), Cooloola Tree Frog (Litoria cooloolensis) and Olongburra Frog (Litoria olongburensis). All these species are similar in appearance (small <30mm and similar body shape) and have a similar call (ratchet like "wreek"). The Northern Dwarf Tree Frog is most similar to the Eastern Dwarf Tree Frog. They occur together along the east coast of Queensland. Litoria bicolor can be distinguished from Litoria fallax most readily by the presence of a bronze stripe that runs down the flanks and the call. The first phase of the call of Litoria bicolor is twice as long as that of Litoria fallax.

References

• Barker, J.; Grigg, G.C.; Tyler,M.J. (1995). A Field Guide to Australian Frogs. Surrey Beatty & Sons.
• Frogs Australia Network - Litoria bicolor - call available here