Cicadas loudest in four years as Sydney experiences a bumper season

Their chorus is so loud in some suburbs (including Bowen Mountain where this journalist lives) that simply being outside amongst the trees, once peaceful, has become a little stressful.

Then, once the sun goes down and the cacophonous chorus calms, the boisterous bugs find other ways to make nuisances of themselves - like flying into the nearest person’s head en route to gather around the glow of the garden light.

Cicadas live for years underground as nymphs, eeking-out existences undetected under the dirt. But once they emerge and shed their shells, boy, do they make their presence known!

The cicada song is actually a mating call sung by the males to attract females, and every species has a particular sound. Cicadas only live between one and four weeks above ground, so procreation is top of their ‘to do’ list.

They’re usually loudest around dusk, and their song tapers off into the evening when they rest. Though if the weather is warm, some species will sing all day, and some individuals will keep going through the night.

According to cicada enthusiast and scientific officer at the Australian Botanic Gardens at Mount Annan, Dr Nathan Emery, cicadas sing in synchrony for mating and survival.

“We call it a ‘cicada chorus’ where one will start and the others will join in. There are two reasons for this: the louder you are, the more attractive you potentially are to mates; and it’s also a better defence against birds because it’s harder for them to find where an individual cicada is calling from,” he told the Gazette.

He said this season is particularly loud not only due to numbers, but also because three of the country’s loudest species have come out to play - the Cherrynose, Double Drummer and Green Grocer.

Hawkesburians can also expect to see Redeyes, Black Princes, Yellowbellies and Razor Grinders, along with some smaller species including the Double-spotted cicada, Alarm Clock Squawker, Sydney Ticking Ambertail and Southern Red-eyed Squeaker.

“When they’re in chorus together they can reach 120 decibels, which is about on par with a chainsaw operating. Anything above about 90 to 100 decibels can be painful to the human ear, and prolonged noise at this level can cause damage,” Dr Emery said.

So how much longer can we expect to hear them? It could be until March or April, according to Dr Emery, though November through to January are typically the loudest months.

Weather has a role to play, too, as long heatwaves and dry spells can kill them off - especially if they don’t have adequate protection against the elements.

The sound of cicadas is synonymous with the childhoods of most Sydneysiders, yet (surprisingly) not much is known about Australia’s species.

Working in plant science as Dr Emery does, knowing a thing or two about cicadas makes sense, however the work he does on the insects is actually a research hobby.

“My dad had an interest in cicadas for the majority of his life, too, and he would take myself and my siblings out to national parks when we were really young and we would catch cicadas,” he said.

He is one of only a handful of cicada researchers in Australia, and unfortunately - like a lot of invertebrate research - there’s not a lot of funding available.

“So the majority of us do it because we’re passionate about it and we fund it out of our own pockets,” Dr Emery said.

He has been tracking cicadas for around seven years now, and recently authored a book called A photo guide to the common cicadas of the Greater Sydney Region, designed as a companion to identifying backyard varieties.

Dr Emery and his pal, Central Coast ecologist Alan Kwok, have been surveying cicadas in Windsor Downs Nature Reserve and the Cumberland Plain Woodlands for three years.

Their research is two-pronged: the first component is taxonomic - classifying different species - and the second is ecological - working out where they like to live and why.

“There are between 700 and 1000 species of cicada in Australia, we think - that’s the most in any country in the world. ‘The cicada capital of the world’, I like to call it. But there’s only 300-350 species that are scientifically described with names,” Dr Emery said.

“We’re trying to understand why we have such a unique diversity here, and also what types of trees they prefer and if they are able to adapt to exotic tree species.

“We’ve been looking at vegetation communities like ironbark forests and scribbly gum woodlands which can be adjacent to each other and - in the short term - we’ve found they have different types of cicadas as well. Even on a local scale there’s a uniqueness from one patch of woodland to the next, and that could be due to things like canopy cover - protection from birds - or they might have a preference to specific trees for their food source.

“But because they’re periodical insects, it makes it very difficult to examine their emerging patterns and distribution shifts, and very hard to tell if one species might be endangered more than another.”

In terms of their cycles, the likes of this summer’s emergence hasn’t been seen since 2013, and before that there was a major emergence in 2010, and before that in 2003.

“There is a potential for a seven-year cycle based on those numbers, but it could also be ten years,” said Dr Emery.

“No one’s been able to put in concrete how long they spend underground, but we think it’s somewhere between five and ten years.”

Dr Emery is appealing to Hawkesbury residents to get involved with a citizen science project he started online - go to inaturalist.org and search for ‘The Great Cicada Blitz’ (or download the free iNaturalist app).

Users can upload photos and audio recordings of cicadas they’ve come across, and submit ‘observations’ for experts to comment on.

“I’d absolutely recommend getting involved. It will help us to look at distribution patterns and emergence over the years, which will allow us to see what effect climate is having on different species,” he said.

“There are a lot of nature reserves and natural bushland in the Hawkesbury, which we think will be very important to cicada diversity in the future.”