Full Breakdown
Bogong Moth Swarm Lights Up Eastern Australia’s Skies and Radar Screens
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Massive Night-time Swarms Confuse Weather Radar
Weather-radar operators across south-eastern Australia have recorded nightly “precipitation” echoes that do not correspond to rain. A Bureau of Meteorology (BOM) spokesperson explained that the echoes are caused by millions of bogong moths migrating southward, appearing on radar as widespread rain. The swarms, which move after daytime resting, have been detected from New South Wales (NSW) into northern and eastern Victoria.
From Decades-Long Decline to a Sudden Surge
Bogong moths once numbered in the billions, with historical estimates of up to four billion individuals aestivating in the Australian Alps each summer. Researchers note a gradual decline from the 1980s, followed by a dramatic crash in the summer of 2017 that left the species “undetectable” in alpine regions. Ecologist Ken Green, who has monitored the moths for over 40 years, attributed the 2017-2019 crash primarily to severe drought, with pesticides and urban light pollution also contributing.
Ecological Implications of the Revival
Citizen-science observations posted to the iNaturalist-based Bogong Watch project show a pronounced increase in sightings this spring, suggesting a population explosion. The resurgence benefits plant pollination and provides a critical food source for endangered species such as the mountain pygmy possum, which rely on moths during the alpine summer.
Official Statements & Responses
He added that the radar signatures are generated by the migrating moths rather than rain.
Verbatim Quotes
- “Initially, most of the radar anomalies were concentrated in NSW, but recent nights have also seen the phenomenon across northern and eastern Victoria,” — Saunders. Bogong, BOM spokesperson