The bogong moth has just been added to the International Union for Conservation of Nature’s red list for endangered species, along with 123 other Australian species.
The bogong moth population has been in steady decline during the past 50 years, however issues were exacerbated by the drought in 2017.
“In 2017, there was a one-hundredfold crash in the population, which was sudden and [something] we hadn’t seen in the past 50 years,” said Jesse Wallace, an ANU PhD scholar in the Division of Ecology and Evolution.
The determination to declare bogong moths endangered in 2021 came from a researcher in Victoria who called on a number of different experts on different species to determine how they should be classified under International Union for Conservation of Nature red list classifications.
What makes the bogong moth so special is its “remarkable migration life history”, said Mr Wallace.
“They’re breeding out on the Darling River, out in the outback, really spread out,” he said.
“In spring, they migrate up to the mountains and aestivate – which is like hibernation but in summer – up in these caves at the peaks of the mountains to get away from the summer heat.
“That habitat – which they occupy for half the year – is, in general, under threat by a number of different things including climate change so that’s a risk going into the future with the bogong moth. That habitat will become no longer suitable for them and they basically won’t have anywhere to migrate to.”
Despite there being more than 1000 species of butterflies and moths in Australia, the bogong moth is so important because it is the only species that science knows of that is migrating across a long distance towards a specific target.
“They do this without having ever been to their destination before, they go to these mountain caves and they’ve never been there before because it’s a new generation every year, but they occupy the exact same cave and the exact same patch of rock in that cave every single year,” said Mr Wallace.
They’re also important because they’re a valuable food source for a number of different animals in their ecosystem, including birds, bats, small mammals, some invasive species and some endangered species such as the mountain pygmy-possum.
Outside of the obvious impact of the drought, it’s difficult for researchers to confidently measure what has caused the consistent long-term decline of bogong moths.
A common belief is that land use is an issue because the agricultural industry considers them a pest species and treats them as such.
Another belief is that the moths get distracted by bright lights along their migration path, and their ability to navigate is impacted dramatically.