Researchers tag thousands of bogong moths to track migration, but none found so far

Every year, billions of bogong moths migrate across the country to New South Wales's Snowy Mountains to escape the summer heat.

In autumn, they leave their cool confines and travel thousands of kilometres back to their breeding grounds inland, but the route remains a mystery.

In an effort to track their movements, researchers from Western Sydney University and Invertebrates Australia tagged more than 14,000 bogong moths hanging in the caves of Mount Kosciuszko in February.

Volunteers hoped to then track their movements by documenting the number of tagged moths found in 50 light traps set up around the mountains.

But so far, none have been found.

Missing moths a 'good' thing

Eleanor Drinkwater, an entomologist at Invertebrates Australia, said losing the tagged insects suggested the population could be in a healthier state than previously estimated.

"It's actually a good thing because the probability of sighting a tagged animal is dependent on how many there are in the population," Dr Drinkwater said.

"In our case, it shows there might be more moths than we thought. There's also the chance that they're taking a different route.

Bogong moths were once abundant across south-east Australia, but the native insect's numbers have fallen sharply in recent years.

In 2017, the population crashed by as much as 99.5 per cent because of drought and climate change, and the species was listed as endangered in 2021.

By tagging the peanut-sized insects and documenting their movements, researchers hoped to raise awareness about the need to protect the species.

The moths were tagged using dabs of non-toxic paint or briefly sedated with carbon dioxide before tiny paper tags were attached to their wings using eyelash glue.

The 'golden ticket' of moths

Kristi Bryant from Cooma was one of the volunteers enlisted to monitor one of 50 custom-built light traps installed across the mountains.

The lanterns attract and trap the moths in a safe place, allowing volunteers to check for a tag in the morning and release them unharmed.

Checking the lamp in the backyard has become part of her young family's morning routine.

"I was really excited throughout the whole thing, and I saw a lot of bogong moths, but none of them was tagged," she said.

Online observations rise

Despite the missing tagged moths, there has been an increase in recorded observations of the insect.

More than 2,700 untagged bogong moth sightings have been logged on the citizen science platform iNaturalist over the past 12 months, up from just over 1,000 observations in the previous year.

Researchers will now use the online observations instead of the tagged moths to create heat maps showing where the moths appear across the alpine landscape, which they will compare with weather patterns to see if there is a correlation.

Photos submitted to iNaturalist will also be used to train an artificial intelligence model to detect moths in footage captured by cameras in the mountains.

The team also hopes to increase the number of lamps to 150 by next year.

While no tagged ones have yet been located, moths have been spotted heading for the Alps again as temperatures start to rise.

"I don't have any theories as to where the tagged moths are, but I'm hoping they're living safe and happy lives and building more communities of bogong moths," Ms Bryant said.