David De Angelis, "NEROC to now", Mar 2019
"NEROC to now: historic and current distribution of frogs in the middle Yarra catchment" David De Angelis is a zoological consultant with an interest in frogs and reptiles. David will be talking about frogs historically recorded in the middle Yarra catchment, species still commonly encountered there and a couple that have recently established outside of their natural range.
If you enjoy a laugh, I recommend watching it with YouTube’s subtitles, to see Eden Angeles Willis, a graduate of a True Beauty, talk about The Distribution of Frogs in the Middle Ear…
What’s better than knowing the current distribution of frog species in Victoria? Knowing the current distribution of frog species in Victoria and the historical distribution of frog species in Victoria! Well-known in herpy circles, David De Angelis pulled in more than 30 people to the Elgin Inn this month to listen to what he had to say about it.
David, Patron Murray Littlejohn and Angus Martin joined the committee for dinner in the dipping sunlight. With $15 parmas of various persuasions available for nourishment, a few attendees were keen to arrive at the Elgin Inn early, to socialise and make the most of the two-hour long happy hour… my favourite kind.
At 7:30, we moved into the function room. Very much unlike the last time we were there, there was even spare chairs! Only a few though, it wouldn’t do to upset the status quo too much.
David De Angelis graduated from La Trobe University with a degree in Biological Sciences with honours research on skinks. Despite his background in reptile research, David was welcomed by the audience with his talk “NEROC to now: historic and current distribution of frogs in the middle Yarra catchment”.
David began by thanking his mentors – Craig Cleland, who was present, Brian Malone, Geoff Heard and Graeme Gillespie, the latter of whom appeared in a photograph in the presentation! Matt Clancy, Marion Anstis, Murray Littlejohn, Angus Martin and Nick Clemann were also thanked for photographs and/or information they had provided.
David finally explained NEROC. I had thought that it must be an Australian name for a geological era that I should have known about, but not so (phew!) – it stands for the North East Regional Organisation of Councils. A paper was prepared for NEROC by Cam Beardsell in the 1990s and it was one of the most comprehensive reports on the frogs of the middle Yarra catchment that runs roughly from Yarra Glen (in the Yarra Valley) to Dights Falls (Yarra Bend Park). David noted that most of the frog distribution data for the area are incidental. Despite how many people live in the Yarra catchment, we know so little about its amphibian residents. Opportunistic records of frog encounters from the Victorian Biodiversity Atlas and the Atlas of Living Australia may not necessarily be reliable but are useful because often that is all we have.
The Common Froglet (Crinia signifera) has likely declined in the area relative to its historical abundance, like so many of our local species. This species is resistant to Chytrid fungus but may act as a vector, passing pathogens around endangered species like the Corroboree Frogs.
The Victorian Smooth Froglet (Geocrinia Victoriana) is hanging on in a few localities and often found along with the Southern Toadlet (Pseudophryne semimarmorata) which as Murray Littlejohn discovered often has its call suppressed by the former. This might go some way to explain why the Southern Toadlet is not detected as much and therefore appears sparse in the records. That and the fact that it spends a lot of its life hiding from people performing frog surveys. Climate change might also be playing a role as its breeding habits aren’t helping it. The Southern Toadlet tadpoles take six months to mature (some other species metamorphose within a matter of weeks). That means that enough water needs to stay in the breeding grounds for all that time and since I have trouble keeping my tomato plants alive because of the lack of rain, I can only imagine how the tadpoles are feeling. Some sites the species was known from in the past have been totally destroyed by development and no rain or groundwater could have saved them. In their favour though, is the length of time this species has to spend trying to replace itself – a lifespan of up to ten years (even up to 20 years in captivity!).
Bibron’s Toadlet (Pseudophryne bibroni) got a mention, but only a controversial one. It seems that it’s now quite unlikely that Bibron’s Toadlets are in the middle Yarra catchment. A combination of confusing morphology and hybridisation has led to a bit of misidentification in some places in the Melbourne area.
The Spotted Marsh Frog (Limnodynastes tasmaniensis) is still reasonably abundant in the area, but it’s an interesting case – it seems that the species has been victim to being moved around by people leading to a very difficult distribution to understand. When found in the northern part of its range, the species sounds slightly different than the southern race. But the species can sometimes be heard with the “wrong accent” suggesting that some individuals have been moved fair distances from their home sites. Further research may tell us, but we do know that it’s happened with other species in the area. Sometimes confused with them are the Striped Marsh Frogs (Limnodynastes peronii), which can also have a pale dorsal stripe (and both species sometimes do not have the stripe), but has stripes instead of spots (as their names might suggest) and is found in slightly deeper and/or more permanent water.
Familiar to many, the Eastern Banjo Frog, or Pobblebonk (Limnodynastes dumerilii dumerilii) is doing fairly well and regularly found throughout in the area. They sometimes seem to disappear, because they can burrow or hide in compost or soil. Funnily enough, I was having a conversation with a friend about accidentally digging up frogs the other day! Southern Banjo Frogs (Limnodynastes dumerilii insularis) (also called Pobblebonks, but a different subspecies) are also found in the region every so often, but are better known from the coastal south of the state.
The Common Spadefoot Toad (Neobatrachus sudellae) has a somewhat scattered distribution. It used to be known throughout the area and probably used to live on the Yarra floodplain. Perhaps more interestingly, similar, closely related species can aestivate for over a year and a half! Obviously, that makes them harder to spot, but what a spectacular adaptation to drought! Southern Toadlets could learn a thing or two from the spadefoots!
David explains the difference between Southern Brown Tree Frogs and Whistling Tree Frogs. Photo by Teisha Sloane-Lay
Southern Brown Treefrogs (Litoria ewingii) are known to many people as common garden frogs. The very closely related Whistling Tree Frog (Litoria verreauxi) looks very similar, VERY SIMILAR. Only really different by the marbling in the groin, width of the digits and the width of the snout. Good luck if you can tell the difference! David explains the differences at 33:10 in the video if you want a better explanation! They do have slightly different calls (video at 34:44), but the hybrid confuses things too – with a call that’s intermediate between the two species.
Lesueur’s Frog (Litoria lesueuri) turns up occasionally in the records. A report from Lilydale proved controversial – even on the night, as a Frogs Victoria event witnessed its first ever heckle! It was a respectful and friendly heckle though, just the way we like them. The species does seem to show up in rocky habitats – where you’d expect it to live – and has been seen in the upper Yarra catchment, so maybe they are still around.
Sadly, the Growling Grass Frog (Litoria raniformis) is not thought to be anywhere in the middle Yarra catchment any more. Development of known sites has sealed the fate of the species for good since about 2004 and David showed us a stark difference in the range over time.
A few species have been introduced to the Melbourne area – including Emerald Spotted Tree Frogs (Litoria peronii) and the Eastern Dwarf Tree Frogs (Litoria fallax). These species, unlike many of their native counterparts are expanding instead of contracting. We don’t really know how they got here and what their impact is, there’s still so much to learn!
David finished with more acknowledgements – we are all so lucky to be surrounded by so many passionate and accomplished herpetologists in Victoria! Everyone in the room had learnt something about the changes in distribution and abundance of frogs in our local area. David’s talk was very informative. I learnt much and find the continued moving of amphibians around the state and the replacement of frogs by human development both fascinating and worrisome. David handled the matters sincerely and comprehensively and despite the apparent broader picture of loss and reduction, most species are hanging on in gardens, parks and reserves and many are still familiar to us.
For the frogs,
Chair, Frogs Victoria.