THE first cicadas of summer have begun to emerge on trees around the Hawkesbury, and the next few weeks will decide whether we’re in for a loud, or a relatively sombre, season on the cicada front.
If you think back to last year in the Hawkesbury, cicadas were so loud they were almost deafening in some suburbs, including Bowen Mountain and Kurrajong.
High numbers of some of the noisiest species had come out for mating - a ‘bumper season’ the likes of which we hadn’t seen since 2013.
But according to Dr Nathan Emery, cicada enthusiast and scientific officer at the Australian Botanic Gardens at Mount Annan, we’re unlikely to experience that sort of activity - and sound - again this year.
“Last year was an absolute mass emergence, and it usually gets a bit quieter for a couple of years after that,” Dr Emery said.
“The important thing to note is that if there’s going to be a decent number of cicadas [this year], they’ll come out over the next week or two, leading up to Christmas.
“But all over the other areas [surrounding the Hawkesbury] it’s looking like it will be a good year, so I would be surprised if we didn’t start to see them in numbers over the next week or two.”
So far this year at Windsor Downs, Dr Emery has recorded a high number of a smaller species called the Sandstone Squeaker (around 2cm long), as well as the Southern Red-eyed Squeaker.
“When it starts to get warmer across Sydney, we start to get the early emergers like the Silver Princess, Zipping Ambertail, and Southern Red-eyed Squeaker - they come out from mid-October and can still go through until December,” he said.
“December and January are the peak of cicada season, that’s when we get the Black Prince, Floury Baker, Cherrynose, Redeye - the larger ones who are more noticeable.
“[In the Hawkesbury] we’ve started hearing the Black Prince, and we’ll hopefully start hearing Floury Bakers over the next week or two. I have heard reports of Green Grocers out in the Hawkesbury as well, but nowhere near the numbers as last year.”
He’s also seen some Double Drummers and Cherrynoses around Windsor Downs, and has heard reports of Redeyes around the lower Blue Mountains.
“It could well be that a lot of the larger ones like Cherrynoses and Redeyes [that we’re seeing emerge now] are leftovers from last season, who didn’t emerge and are delayed until this year. It could be a long tailing-off but across a subsequent season,” Dr Emery said.
The truth is, not a lot is known about cicadas and their patterns, so asking someone like Dr Emery to forecast which species will come out on any given year is fraught with difficulty.
The invertebrates provide the soundtrack for many a Sydney summer, and yet there has been limited research on them over the years, mostly due to limited funding.
Experts like Dr Emery are self-taught, and dedicate hours of their own time researching local cicadas, their habitats and their patterns, all for the love of it.
He and his team are now in their fourth year of tracking cicadas at Windsor Downs and Castlereagh, and on many fronts they still have more questions than answers.
Based on their research, there is a potential for a seven-year cycle that the critters spend underground in their shells as nymphs, however it could also be ten years - no one knows for sure.
“We’re now at the point where we’re starting to analyse and look into that data and look at trends,” he said.
For instance, they have ascertained what looks to be different diversities of cicada species populating certain vegetation communities.
“Some species are more generalised and will emerge in multiple communities, but a handful are more specific and confined,” Dr Emery said.
“Potentially, it plays to that idea that having these reserves in isolation is important because there may not be that movement - travelling between reserves - if you don’t have those corridors.”
Dr Emery is the author of a book called A photo guide to the common cicadas of the Greater Sydney Region, designed as a companion to identifying backyard varieties.
He is appealing to Hawkesbury residents to get involved with a citizen science project called The Great Cicada Blitz at inaturalist.org. People can upload photos and sound files of cicadas they find, helping Dr Emery and his team track their emergence around Sydney.
“We’re also encouraging people to [upload photos of] the plant species that they observed the cicada on, giving us an idea of whether some species prefer particular plant species, and whether they’re adapting to more exotic plants like camphor laurel and plane trees,” he said.