Star-guided journeys: scientists reveal moths migrate over 600 miles using celestial navigation
New research finds that Australia’s endangered Bogong moths use the stars to make an epic round-trip migration through the night sky.
For most of us, navigating 600 miles without GPS is out of the question. For the Bogong moth, on the other hand, it’s a matter of life and death. This unremarkable-looking insect – brown, nocturnal, wingspan the size of a postage stamp – pulls off one of nature’s great migrations every year across southeastern Australia. And the trick is, as our pre-digital voyaging ancestors, by using the stars.
Migrating insects that read the stars
In spring, Bogong moths (Agrotis infusa) emerge from the soil and begin an overnight migration of up to 620 miles, heading for cool alpine caves in the Australian Alps. They go dormant there for the summer, before flying all the way back in fall to mate and die. It’s a round trip most of them make just once... and without a guide.
This latest study, published in Nature, confirms something scientists had only speculated: Bogong moths navigate using a built-in stellar compass, a technique previously known only in birds and humans. Unlike other invertebrates that use celestial cues in simpler ways - like dung beetles rolling their treasure in a straight line – these moths use the stars to orient themselves toward a precise location they’ve never seen before.
Even more impressive, the stars aren’t their only tool. Past research shows they can also sense Earth’s magnetic field. The result is a two-part backup system: magnetic compass by cloudy night, celestial compass under a clear sky.
A natural compass in a tiny brain
The discovery came out of an ingenious lab experiment set up by Eric Warrant, a neurobiologist from Lund University. His team tethered moths in a specially built arena, projecting the night sky onto the ceiling while eliminating the magnetic field using a device called a Helmholtz coil. That meant the only orientation clues came from the stars.
They then saw moth after moth flying in the correct migratory direction – south in spring, north in fall – even when deprived of all landmarks or magnetic cues. When the researchers flipped the night sky 180 degrees, the moths reversed course, confirming they were relying on the sky’s layout to navigate. Impressed yet?
If that weren’t enough, the team also found neurons in the moths’ brains that fire in response to specific rotations of the night sky. Some cells even appear to be tuned to the orientation of the Milky Way – especially its brightest region, the Carina nebula. These neurons were all calibrated to fire maximally when the moth was heading south, which aligns with the spring migration toward the Alps.
It’s worth noting that while extraordinary, Bogong moth populations have crashed dramatically, landing them on the IUCN Red List. Habitat loss, pesticides, and climate change are all to blame. They’re likely not part of the animal kingdom that jumps to mind when considering our actions, but hopefully this is a reminder of the brilliance of even the smallest creatures.
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