The Eastern Sedge Frog (Litoria fallax) is a tiny green hylid found on the east coast of Australia. These frogs were photographed near Mareebra Wetlands Park in Queensland.
These Sedge Frogs were calling from a garden pond in a group of villas we were staying in within the town of Port Douglas. The call consists of a dry upward trilling interspersed with a few clicks.
From my limited experience and research, this species is very similar in size, shape and behavior to the Northern Sedge Frog (Litoria bicolor) and can be very difficult to distinguish in NE Queensland where they overlap. Supposedly there is a difference in their calls, but I am still working on learning that difference. The written descriptions have not been that helpful so far but a CD of the recordings that I bought online has helped me understand the difference a bit better.
Here is a single recording of a Litoria fallax from near Lake Mitchell, QLD -
and here is the spectrogram of that recording -
You can see that the call consists of a longer upward buzzy trill followed by a number of shorter sharp "clicks". The number of clicks following the trill seems to vary from 1 to 3 (or a few more).
I am going back over my Australian recordings to see if I recorded any Litoria bicolor, but for comparison I have created a spectrogram of a single call of a Litoria bicolor from David Stewart's excellent recordings* -
The obvious difference is the series of clicks prior to the upward trill of the call. To the ear, this sections sounds like a quick double click, and upward buzzy trill and a follow-up double click. Once again, the number of clicks after the trill varies but it is the pre-trill clicks that seem to distinguish this species.
* I highly recommend David's excellent frog call CD's to NE and SE Australia (http://www.naturesound.com.au/cd_frogsTNE.htm and http://www.naturesound.com.au/cd_frogsSE.htm) for anyone interested in learning or studying Australian Frog calls. I purchased two CD's from him online and they arrived in the US within a week!