Mass migration of bogong moths surprises Australian researchers
The threatened moth is being reported in exceptionally large numbers along the east coast this spring.
Large numbers of bogong moths have appeared in parts of the Australian state of New South Wales. Researchers regard the mass migration as notable, but warn that isolated sightings do not yet prove a recovery of the species.
Since the end of September, residents along the coast have reported large swarms of bogong moths. According to ABC News, around 800 sightings have been recorded on the citizen-science platform iNaturalist, more than 200 of them within a single 24-hour period. The moths normally migrate to the Australian Alps in spring, where they spend the summer.
The bogong moth is a small nocturnal moth that provides an important food source for animals in the Australian Alps. The species has been listed as threatened on the IUCN's international Red List since 2021. In 2017, the population collapsed by as much as 99.5 per cent, according to researchers.
Researchers have put forward several possible explanations for the current numbers. More rain, a warmer winter and favourable northerly winds may have influenced the migration. These are explanations based on weather conditions and observations, not an established cause. There has not yet been a full population count for the current season.
The large numbers are therefore ambiguous. On the one hand, they show that many moths are arriving in at least certain places. On the other, a local swarm can arise through migration from a large area without the total Australian population having recovered. Numbers also vary from year to year and according to the measurement method.
Scientists are asking residents to continue reporting sightings. The data could help track the route and timing of the migration more accurately. Western Sydney University is working with the Bogong Watch project to study the species' distribution and the consequences for predators that depend on the moths.
The return of the swarms is therefore good news for researchers, but not yet proof that climate pressure and habitat loss have been resolved. The species remains vulnerable. Prolonged drought, higher temperatures, light pollution and changes in mountain areas in particular may continue to affect migration and reproduction.
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The sightings, threatened status and historical population crash have been described by ABC, SBS and research institutions. Possible causes have been presented as hypotheses, not as a proven climate link.
- confirmed Around 800 sightings have been recorded on iNaturalist. — ABC News reports this figure. source
- confirmed The bogong moth has been listed as threatened on the IUCN list since 2021. — ABC, SBS and the Australian Conservation Foundation mention this status. source
- confirmed The population collapsed by as much as 99.5 per cent in 2017. — Mentioned by ABC News and scientific literature. source
- uncertain More rain, a warmer winter and northerly winds may explain the current migration. — These are possible explanations from researchers, not an established cause. source
Editor's note
The large number of sightings and the threatened status have been confirmed. The possible relationship with rainfall and temperature is a hypothesis put forward by researchers; a recovery of the total population has not yet been demonstrated.Sources
- Endangered bogong moths swarming into homes across NSW — ABC News
- Bogong moth migration is giving researchers hope — SBS News
- Western Sydney University expedition to tag 10,000 Bogong moths — Western Sydney University
More on this in Dutch media
- NOS — „australië bogongmot”
- Het Parool — „australië bogongmot”
- de Volkskrant — „australië bogongmot”