A happy Pobblebonk
I know these Pobblebonk frogs really well from their distinctive banjo-like “bonk” call. There are some swamps near Raakajlim which are just full of them calling in the evening. (If you listen carefully to the recording you can hear the moment Phil nearly stepped on a snake!)
Turns out, I’m not that great at picking the key diagnostic features that make it a Pobblebonk (also known as a Southern Bull Frog, Banjo Frog or Limnodynastes dumerilii dumerilii).
“What’s that?” asked my husband, pointing to the big bulgy sac below the eye. “That’s the tibial gland.” I replied confidently, “That’s what makes the Pobblebonk different to the Mallee Spadefoot toads.” He looked at me, eyebrows raised, “But wouldn’t a tibial gland be on the leg, you know like the tibia leg bone?”. I scrabbled through my field guide, “Mmmmm, maybe,” I conceded.
The bulging sac on the back leg is the tibial gland.
And here’s a photo showing the bulgy bit below the eye, actually called a “pale glandular stripe”.
Although the pupil looks round to me, the books describe the pupil as horizontal, again distinguishing it from the Mallee Spadefoot toads which have a vertical pupil.
Okay, so here’s a photo showing the tibial gland which is the warty lump on the back leg. The Spadefoot toads (Neobtrachus pictus and N. sudelli) don’t have a tibial gland.
The stripe below the eye is termed the glandular stripe. Note the round / horizontal pupil.
The genus Limnodynastes means “lord of the swamp”. Oh, and it is, so many and so noisy…
It’s a burrowing frog which explains why I dug it out of my vegie patch, but I have seen them out and about during the rain (when it rains). It’s a common frog in Victoria and is not considered threatened.
First published September 26 2020. Updated 2021.
Finally, a shout out to the free FrogID app from the Australian Museum (https://www.frogid.net.au/).
It has a super-useful predictive field guide for your location, as well as the calls of all the frogs. It’s been developed as a citizen science project to monitor why some frogs are flourishing, whilst others are declining. You can make a recording of the frogs calling in your area, submit it via the app, and you get back a nice email confirming which species of frogs were on the recording. My email came from a real person who added a thank-you note and a smiley face. I was very impressed.
Now is the time to download the app. The Mallee CMA is running a frog monitoring project here and there might be a free head torch for you. It’s Frog ID week soon too - Friday 12 November to Sunday 21 November 2021.