Frog Blog

This is an example of the wonders of the internet.

I posted the following two pictures  of a frog on Flickr, with the attached comment (in green):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Helen and I came across this pretty little tree frog, about 15mm long, while hunting for caterpillars. Helen, whose main area of expertise centres around butterflies and other invertebrates, identified its genus as litoria, but didn't know which one. When I looked it up, I could see why: there are about 150 different species, with new species being discovered each year.

Litoria, apparently, is a genus of Australasian tree frogs distinguishable from other tree frogs by the presence of horizontal irises, and no pigmentation of the eyelid. So far so good.

I was able to discount the Red-eyed Tree Frog, the Green-eyed Tree Frog, the Spotted-thighed Tree Frog, the Orange-thighed Tree Frog and the Sharp-snouted Tree Frog.

As we were at Woodford, near Brisbane, I was able to eliminate the Northern New Guinea Tree Frog, the Cape Melville Tree Frog and several others. In the absence of any sound while we were watching, I tentatively dismissed the Bleating Tree Frog, the Buzzing Tree Frog, the Whirring Tree Frog, the Growling Grass Frog and the Maniacal Cackle Frog. This only left over a hundred others.

After looking at pictures of tree frogs (something I've never really done much ) I've decided it might be a Pearson's Green Tree Frog (Litoria pearsoniana) for the following reasons:

Distribution: Rainforest creeks from north of Lismore, New South Wales to Kenilworth, Queensland.

Physical description:
Size: Small, up to about 40mm.
Colour: Green, with a head and shoulder stripe.
Groin Colouration: None present.
Tympanum: Distinct, brown in colour. (I have learnt a new word! This is the hearing organ of a frog, beside its eye. Just to put you off the scent, a tympanum can also be an architectural element located within an arch or pediment, or a circular, drum-like rack on which victims can be tortured.)
Head stripe: Light brown with a thicker brown underline, passes through the tympanum.
Belly: White or off-white.

I would be grateful to know if this is the correct identification.

After a few days, I received the following reply from ecologist Evan Pickett, currently based in Newcastle, NSW.  Evan has given his permission for me to quote his reply here.  I was surprised and a bit sad to learn that female frogs don’t get to make any of the bleating, buzzing, whirring, growling or maniacal cackling noises described above.  But at least I now know that what we saw was not a Pearson’s Tree Frog, but an EASTERN DWARF TREE FROG.  Thank you Evan!

You are close with your ID, but not quite. This is an eastern dwarf tree frog (Litoria fallax). The major difference is the colouring on the lateral section and it has a more triangular head. (Litoria pearsoniana is more box shaped). L. pearsoniana is also a stream dwelling frog, whilst L. fallax inhabits ponds (and occasionally slow flowing streams with pools).

I also noticed that you dismissed a few species because you didn't hear it making the call described in their common name. All Australian frogs call to attract mates; common names are often arbitrary and should generally be ignored. The call is a very good way of identifying frogs, but a lack of call just means it is either the wrong time or conditions to call or it is a female.

Thanks,

Evan.