A strange repetitive sound has led an Aussie gardener to make a fascinating discovery in her backyard. The noise definitely wasn’t a cicada and it was “rougher, with different tones” than an ordinary cricket chirp.
“It was late at night, and coming from a little patch of soil. I just stood there listening and it didn’t stop. Normally, you walk near a cricket and make some noise and it stops,” Melbourne woman Sabina Anderson told Yahoo News.
Anderson was right, the chirping she heard was not being made by an ordinary black cricket — a “boom and bust” species that blanketed her city last summer after unseasonal and persistent rains.
World-renowned expert identifies odd garden sound
The sound was identified by a leading CSIRO entomologist and taxonomist You Ning Su as a more unusual species — a native mole cricket. But its call was slightly different to what he’d ordinarily expect to hear.
“It seems to have been produced either by a newly matured individual or one that was disturbed. Typically, the song consists of either a long, consistent trill or regular chirps,” he told Yahoo.
Rather than being frightened away, it’s often human activities that stimulate calls from the odd-looking creatures.
“Mole crickets are nocturnal and normally start to sing in the evening. Moisture will also stimulate them to sing, so people tend to hear the calling after the rain or the garden irrigation spraying,” Su said.
What’s different about mole crickets?
Mole crickets are brown in colour and much stockier than black crickets. They’re easily identifiable by their shovel-like fore legs which have been described as looking like hands.
Su is the author of ‘A Guide to Australian Grasshoppers and Locusts’ and he was easily able to identify the mole cricket in Anderson’s yard as a native species from the Gryllotalpa genus, and not an introduced Changa mole cricket (Scapteriscus didactylus) which is now found in parts of northern NSW.
Mole crickets are omnivorous and may damage the roots, but they play an important role in the ecosystems as a food source for birds and small mammals, and they play an important role turning composting soil, so they should never be poisoned.
Mole cricket species are well-known for their shovel-like hands. Source: Wikimedia
Because they have a modified chamber to amplify song, their call is at a low frequency of around 1 to 3 kHz, while true crickets are 4 to 10 kHz.
Two weeks after Anderson recorded the cricket in November, she spotted another mole cricket in her garden.
Looking at her images, Su identified it as a female, and not the same individual whose song was recorded.
Major threat to Australia’s diverse cricket populations
While climate change is having a big impact on Australia’s wildlife, Su believes the biggest threat to crickets is urbanisation.
Population booms occur when rains spark sudden growth in feed, but when the natural world is covered in concrete there’s nothing for them to eat.
While there are hundreds of native cricket species in Australia, many of them are picky when it comes to diet. That means even when a garden is planted after developments are complete, it will often be the more abundant and hardy varieties that return.
“Before they develop the land they wipe out all the vegetation, and then people grow introduced plants. If the area is big enough they will wipe out everything,” Su said.
“Introduced lawn grass and plants won’t allow them to come back, because it’s not the habitat it used to be. So urbanisation makes a big impact on not only crickets but everything.”
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