Bogong moth sightings surge in New South Wales, but recovery remains uncertain

Bogong moths have appeared in unusually large numbers in parts of New South Wales during their spring migration, raising hopes for an endangered species whose population crashed in recent years. Researchers told The Guardian that the reports are encouraging, but the sightings do not establish that moth numbers have recovered across their range.

Coastal sightings were posted over the weekend to Bogong Watch, a citizen science project. Its manager, Linnea Emneby, told The Guardian that volunteer monitors around Mount Kosciuszko were also seeing high numbers. Three NSW households reported dozens of moths on Monday, while one volunteer saw more than 200 on Sunday night, she said.

A strong start to the migration

Marissa Parrott, a reproductive biologist at Zoos Victoria, told The Guardian that reports to its Moth Tracker project during September had already exceeded the number received throughout 2025. Sightings had increased over the previous two years, she said, but this season was substantially higher. The larger numbers were concentrated in NSW and the Australian Capital Territory; Victoria was still behind.

Parrott suggested wetter, cooler weather may have favoured the moths. She also said their migration moves in waves and can take days or weeks. Those qualifications matter when interpreting a burst of observations from particular places: the present reports show where people are encountering moths, rather than providing a count of the entire population.

Why researchers are cautious

The species was listed as endangered by the International Union for Conservation of Nature in 2021, The Guardian reported. It said an estimated four billion moths once reached the Alps each year before numbers fell by as much as 99.5% between 2017 and 2019. Against that history, a busy migration season is welcome, but a lasting recovery would require evidence extending beyond this wave of public reports.

Earlier independent reporting offers a useful comparison, though it measures a different period. ABC News reported on 6 September that more than 2,700 observations of untagged bogong moths had been logged on iNaturalist over the preceding 12 months, up from just over 1,000 in the previous year. Those figures show increased recorded activity before the latest NSW reports; they are not a standardized estimate of how many moths exist.

Identification is another limitation. In a 17 September appeal for Moth Tracker sightings, Zoos Victoria said only 58% of submissions in the previous year were confirmed as bogong moths. The project collects dates, locations and numbers during the annual migration. That information can help researchers follow movements, while also showing why a raw submission total should not be treated as a verified count of the species.

Federation University's Centre for eResearch and Digital Innovation, which collaborates with Zoos Victoria on Moth Tracker, says public observations can improve understanding of migration and the availability of moths as food for mountain pygmy possums. The records are valuable because they cover places researchers cannot continuously monitor, but the reviewed material provides no complete, comparable 2026 census across the moth's range.

What researchers are tracking next

A separate project illustrates both the effort to map the migration and the gaps that remain. ABC reported that researchers tagged more than 14,000 bogong moths in February and volunteers checked 50 light traps around the Snowy Mountains. None of the tagged moths had been found by the time of its 6 September report. Entomologist Eleanor Drinkwater said that might mean there were more moths than expected, or that the insects had taken another route; neither explanation was established.

According to ABC, the research team planned to use online observations to map where moths appear and compare those patterns with weather. It also planned to train a model on submitted photographs to detect moths in mountain camera footage, and hoped to expand the light-trap network to 150 the following year. These projects may clarify movement, but their results cannot yet settle what the latest NSW surge means for population size.

Parrott told The Guardian she hoped the strong reports signalled a firmer recovery. She also warned that hot, dry conditions associated with a strong El Niño could affect the moths in coming years. The current regional imbalance adds another unanswered question: NSW and ACT reports are high, but the available account says Victoria has not seen the same increase, and does not provide directly comparable regional totals.

For people who encounter the moths, experts quoted by The Guardian recommend switching off unnecessary outdoor lights, avoiding insecticides and submitting sightings to Moth Tracker or Bogong Watch. Parrott said moths that enter a home can be gently moved outside. Continued observations can help researchers follow this migration; determining whether the endangered species is recovering will take broader evidence over time.