For five years the Bogong moth has been in dire straits, with extreme drought conditions in 2017 pushing the species to the brink of extinction, but experts say they may be making a comeback.
The Australian Conservation Foundation's 2022 Bogong moth migration snapshot found population numbers seemed to have increased, but are still a long way from the billions of moths seen before they were declared an endangered species.
The small and unassuming brown invertebrate only measures about 3 centimetres from head to wingtip, but it is an important part of many Australian ecosystems.
Bogong moths pollinate plants along their migration route to the Australian Alps, and are an essential food for native animals including ravens, lizards and the critically endangered mountain pygmy-possum.
Before the majority of the population was decimated by climate change, Bogong moths provided the second-biggest input of energy into the Australian Alps, second only to the sun.
Each spring, billions of Bogong moths migrated from their breeding grounds in southern Queensland, north-western New South Wales and Victoria to caves in the Snowy Mountains.
They used to arrive in such numbers that they flooded the nation's capital during their annual migration, getting into Parliament House and even troubling athletes at the Sydney Olympics.
Population crash of up to 99.5 per cent
Darcie Carruthers, a nature campaigner with the Australian Conservation Foundation, said the Bogong moth population dropped by up to 99.5 per cent due to drought conditions.
"Four, five years ago there were really brutal drought conditions in some of the Bogong moth breeding grounds, like up in central NSW," she said.
"Many of the Bogong moths who start out their lives as larvae and pupae in the ground likely never made it to the adult stages of life, and those that did probably didn't have enough to eat."
She said similar conditions persisted for a few years, slashing the population.
"[It's] a really frightening example of how severe drought conditions can cause a once-prolific species to crash at a population level and basically disappear before our eyes," Ms Carruthers said.
"Really, really biting drought conditions [were] exacerbated by climate change, and the Bogong moth actually went from around 4.5 billion individuals to barely being even detectable."
Carruthers says moth 'definitely isn't out of the woods'
While more Bogong moths are migrating this year than in the past five, Ms Carruthers said the population was still definitely not back to pre-2017 levels.
"It's good news, but it's really important to remember that all of those things that are threatening the existence of this species very much still remain," she said.
"The Bogong moth definitely isn't out of the woods."
Ms Carruthers said she was "very worried" more drought conditions could cause the population to swiftly decline once again.
And the Bureau of Meteorology's State of Climate report suggests severe drought conditions are likely to become more frequent in the future.
"The Bogong moth population doesn't have the resilience that it once did, and a return of those drought conditions could be really disastrous for this species," she said.
"Unfortunately, the Bogong moth is facing a number of threats, and top of the list is climate change."
Ms Carruthers said the report was all the more reason that serious action on climate change needed to be taken to protect the Bogong moth.
"That means replacing fossil fuels with renewable sources of energy, ruling out new gas and coal projects entirely, and making sure that we're addressing climate change at the source so that species like the Bogong moth aren't suffering from its impact," she said.
"The fact that they have been able to make a bit of a comeback and show some resilience is all the more reason to address those threats and really help this species remain into the future."
