Adam Woods and Brendan Casey: Bioacoustics double bill Apr 2019
Two speakers, one subject: Adam Woods and Brendan Casey spoke about the dulcet tones of our favourite animals. Wall to wall frog calls for the entire evening!
We met at 6 in Captain Melville – a first for us to grab a pub meal in an establishment different from the presentation venue. As such we hadn’t anticipated many would join us for dinner, but our large table was soon full and chairs were hastily added until we had all but blocked the path from kitchen to dining room.
After dinner, the wind blew us across the unfamiliar habitat of Melbourne CBD to the RMIT Swanston Academic Building. How many guests couldn’t find the room I suppose we will never know, but more than 30 people took their seats, many remarking on the new-fangled technology of a modern classroom. Or maybe that was just me.
Adam Woods, FrogID
Frog ID Project
Our first speaker was Adam Woods, who had travelled all the way from the Australian Museum in Sydney to tell us about the FrogID project. Well I don’t think he came just for us, but nonetheless we were very honoured.
We heard about the background to the Frog ID project and many people in the room were familiar with the FrogID app and use it regularly. But Adam had some really interesting insights – apparently, Victorians are big fans of recording frogs when they travel, but are less inclined to record frogs in their home state. Which means that there are gaps through Victoria – even in places where there are people who have the app.
Adam shared with us some beautiful photographs taken by Stephen Mahony, who was also in the room, despite the best efforts of the technological demons that frequently haunt the modern technology of lecture rooms. Whether you were there or not, I encourage you to look for him and his beautiful work on Instagram (@svmahony) and see what you missed.
The FrogID project has really (literally) put frogs on the map for many Australians. Not just frog-loving types, but also people who didn’t even know they cared. It is a great story of science and outreach for all involved and we look forward to seeing what the project’s future holds.
Bioacoustic Monitoring of Frogs, progress and results so far
Brendan Casey is a research student at RMIT and told us all about his project – the bioacoustic monitoring of frogs. Brendan is about half way through his Ph.D. and began his presentation by thanking his supervisors, volunteers, RMIT, the Ecological Society of Australia and Parks Victoria, all of whom have provided support for the project one way or another and many of which are familiar to researchers as integral to the conduct of research in Australia.
Brendan began his first season searching for locations and candidate species for his research. He had no equipment or plan, which I suppose is how most research starts. He began by choosing a local storm water pond that seemed like a good place to start and put his first recorder there, recording 10 minutes of every hour. Brendan put a second recorder at a pool in the Merri Creek flood plain, a place where he had heard Growling Grass Frogs (GGFs) in the past and as he confessed to being partial to wanting to study the species, he thought it might be fun to see if the GGFS are still there. A third recorder gave Brendan the opportunity to make recordings at an old tip site, where pools are always kept wet in case the water is needed for fire-fighting.
In the first year, Brendan met many challenges that will be familiar to people trying to study frog calls: background noises, frogs calling at the other end of the pond from the recorder, information posing more questions… Brendan also had a problem that a lucky few suffer from in their first season – too many data! Brendan said that he hadn’t expected to record anything initially, but he has over 17,000 frog call files!
The GGFs in the recordings were good at calling at seemingly random times. No one could have predicted the lack of pattern in their call activity. Brendan thinks that the patterns seem to be local to each site – different at all three sites. Mostly, the frogs favoured calling between midnight and 4am at one site. At the other two sites, there was no convincing pattern in the time of day they called. But at all three sites the frogs went quiet mid to late afternoon. Much like myself.
Brendan played us some calls through a “Kaleidoscope” viewer which gave us a visual representation of what we could hear. We were transported to a sunny day by a pool listening to a little grassbird singing away, accompanied by many Growling Grass Frogs. The GGFs complied with everyone’s expectations – they growl, in an unmistakably frog like way. Some call files demonstrated a few, sparsely calling frogs and some files were constant calls from many animals, more than anyone could hazard a guess as to how many there could be!
Unfortunately, one of Brendan’s sites was renovated and he ceased surveys there. One recorder was stolen and the seal broke on the third recorder which was subsequently taken over by termites! There ended his first season.
Brendan’s second season was to be more refined, as most people’s second field seasons are! Brendan decided to concentrate on one site, have a longer recording period, log air and water temperatures, measure water parameters, record all the frog species and use a hydrophone. He also replaced the stolen recorder and put a security case around it!
The hydrophone was used to see if the GGFs calls could be heard under water. Their vocal sacs sit just under the water’s surface when they call and Brendan tested the hypothesis that they communicated through the water. Brendan couldn’t find any evidence for it though, somewhat to the disappointment of the audience! Brendan did manage to record Eastern Froglets, Southern Brown Tree Frogs, Spotted Marsh Frogs Pobblebonks and Peron’s Tree Frogs in addition to GGFs though. He considered that the data for the species other than GGFs seem to be of good quality – as they call less frequently, recording the entirety of their calling season is a lot easier.
The call of Crinia signifera as we’d never seen it before. Photo by Teisha Sloane-Lay
Brendan is also interested in the calls themselves – the calls, notes, pulse, frequency and bandwidth. We listened to recordings of the frogs and saw diagrammatic breakdowns of the call types. Everyone loves a visual aid! We heard and saw all kinds of GGF vocabulary – grunt calls, fast calls, growls and even a combination! We also saw a video of a “squeeze call” (not filmed by Brendan), showing the endearing and somewhat heart-wrenching agonistic call of a GGF.
Frog calls are incredibly complex – not just at the population scale, but Brendan says that each call itself may mean something. Frogs might have conversations just as we do, although as Brendan says, they can likely be classified as either “come here” or “go away”! Maybe we’re not so different after all.
Brendan is also trying to record the calls of the Giant Burrowing Frog (Heleioporus australiacus) but the areas he has been studying have been extremely dry and without any substantial rain, the frogs will likely remain quiet. We of course wish for the sake of both the frogs and Brendan that we have more rain.
Brendan finished by requesting suggestions for his research and answers to many of the questions that his research has posed. The more you know, the more you know you don’t know! But we all know a lot more about the calls of Growling Grass Frogs and the FrogID project than we did at the pub just an hour and a half earlier!
Brendan Casey, "Bioacoustic monitoring of frogs"
More information about the FrogID project can be found here: https://www.frogid.net.au/
To listen to some of Brendan’s recordings go to https://www.nfsa.gov.au/ and type Growling Grass Frog into the search box.
For the frogs,
Chair, Frogs Victoria.