Thursday, 12 January 2012

The Amphibians of Bauple

Mixophyes fasciolatus. Photo: Ryan Pearson
By Ryan Pearson
Last month I was out bush helping with the field work for a PHD student. During this week in the bush (in and around Bauple, QLD, Australia), we encountered many different types of frog and toad. I'm going to use this space to talk a little bit about the amphibians we found, but also the process of identifying these creatures.
Firstly, I mentioned this briefly in my last post, but the amount of cane toad's we came across, and that ended up in the traps was incredibly disturbing. The cane toad is an introduced species which was brought to Australia in an attempt to control the cane beetle. This ploy failed dismally, and the cane toad has become one of the most prolific pests in Queensland, which is also quickly spreading throughout the rest of the country.
Rhinella marina. The Cane Toad. Photo: Ryan Pearson
By far the most common creature we caught was the cane toad. They fell into the pitfall traps, and even jumped into the elliot traps. At one site, we had about 13 cane toads in each of the four pitfall traps. The next most abundant species in my time there would likely have a catch count less than a tenth of the cane toad. Being a toxic species, many of the predators of the cane toad (mostly native species) end up dying from ingesting their poison. This goes to show how important quarantine can be, and how unexpected the outcomes can be when a foreign species is intentionally introduced.

Anyway, with that rant out of the way, we can move onto the frogs (because cane toads were the only toad species we found). I'll start by describing some of the methods used to identify frog species. You see, there are a number of distinguishing features in frogs that tend to remain relatively constant within a given species, and overall colour is not generally one of them. Some of these features include thigh colour, iris direction (horizontal or vertical), amount of webbing between toes, patterning, and even their call. 

Here are some pictures taken to help us try to ID this frog (trying to get as much detail as possible, and cover all aspects commonly used in identification):

Trying to gauge iris direction (vertical). Photo: Ryan Pearson

No webbing on any of the four front toes. Photo:Ryan Pearson

Displaying the patterning on the back and legs. Photo: Ryan Pearson

The thigh colour shows a pinkish tinge. Photo: Ryan Pearson

And one of the face for good measure. Photo: Ryan Pearson
This particular species ended up being Limnodynastes ornatus, or the Ornate Burrowing Frog. As you can see here, the colour of the species is not an indicative feature as an individual can have a 'wide range' of colours.
Limnodynastes ornatus. Ornate Burrowing Frog. Photo: Ryan Pearson

There were two other members of the Limnodynastes genus that ended up in our pitfall traps. The Striped Marsh Frog (Limnodynastes peronii), and the Northern Banjo Frog (or pobblebonk) (Limnodynastes terraereginae).

Limnodynastes peronii. Striped Marsh Frog. Photo: Ryan Pearson
Limnodynastes terraereginae. Northern Banjo Frog. Photo: Ryan Pearson
Limnodynastes terraereginae. Northern Banjo Frog. Photo: Ryan Pearson
There was also the Great Barred Frog (Mixophyes fasciolatus).
Mixophyes fasciolatus. Great Barred Frog. Photo: Ryan Pearson
And the Copper Backed Broodfrog (Pseudophryne raveni)
Pseudophryne raveni. Copper Backed Broodfrog. Photo: Ryan Pearson

Then there were the tree frogs... we found most of these within a 10 minute period in about a 5 square metre area next to a pond where we were staying. But before that, while searching for the frogs we saw something quite unique... a water beetle holding onto, and swimming around with a dead frog. I can only assume it was eating it.

Photo: Ryan Pearson

Photo: Ryan Pearson

The tree frogs were incredibly numerous, we were often woken by their calls, and had ventured out on this night to find one whose call sounded just like a lamb. It turned out to be this guy...
Roths Tree Frog caught mid call. Litoria rothii. Photo: Ryan Pearson
Other tree frogs included the Desert Tree Frog, the Broad Palmed Frog, the Eastern Sedge Frog, and lastly the Common Green Tree Frog.
Desert Tree Frog. Litoria rubella. Photo: Ryan Pearson
Broad Palmed Frog. Litoria latopalmata. Photo: Ryan Pearson
Eastern Sedge Frog. Litoria fallax. Photo: Ryan Pearson
Common Green Tree Frog. Litoria caerulea. Photo: Ryan Pearson

No comments: