These Tiny Moths Use the Stars to Guide Them Hundreds of Miles

According to a study published in the journal Nature, bogong moths, like birds, use a stellar compass for their migration.

“Each spring, billions of Bogong moths escape hot conditions across southeast Australia by migrating up to 1,000 km to a place that they have never previously visited—a limited number of cool caves in the Australian Alps, historically used for aestivating over summer,” the study abstract reads. 

“At the beginning of autumn, the same individuals make a return migration to their breeding grounds to reproduce and die,” the study authors continued. “Here we show that Bogong moths use the starry night sky as a compass to distinguish between specific geographical directions, thereby navigating in their inherited migratory direction towards their distant goal.”

What are bogong moths?

Bogong moths are an endangered species of night-flying moths known for their biannual seasonal migrations. Now, a new study has discovered that these insects use the stars to navigate.

Essentially, the researchers used a flight simulator to discover that moths actually fly in “seasonally appropriate migratory directions.” They also found that visual interneurons in their brain responded to specific angles of the night sky, suggesting that these moths actually use stars as a form of navigation. 

“The big thing that we’ve discovered here is a very, very tiny animal like a moth, with a very small nervous system, a very small brain, very small eyes is able to interpret the starry night sky and work out a direction to fly in,” Eric Warrant, a professor of zoology at Lund University in Sweden and an author of the research, told NBC News.

He added that, despite having small pupils and a limited vision of stars in the night sky, these moths likely see the Milky Way more distinctly than humans do. 

Not to mention, the insect is the first known moth to use stars as navigation.

Bogong moths use a stellar compass to migrate

According to the study, even during overcast nights when the stars and moon are not visible to the insect, bogong moths are still able to navigate. Researchers concluded that this means they use the Earth’s magnetic field in the absence of stars.

“Our behavioural results demonstrate that Bogong moths, like night-migratory birds, use a stellar compass and a geomagnetic compass and, like birds, remain oriented in their inherited migratory direction when at least one is available, either the natural stars alone or the Earth’s magnetic field alone,” the researchers wrote. “When neither cue is available, the moths are disoriented.”

Addressing the decline of bogong moths

As mentioned earlier, the bogong moth is an endangered species. In fact, it was added to the International Union for Conservation of Nature’s “red list” in 2021. 

“The moth population has been decreasing dramatically in numbers over recent years, especially with the drought and the bushfires that Australia had in 2020,” Andrea Adden, a postdoctoral researcher who studies at The Francis Crick Institute and one of the researchers on the study, told NBC News.

Thankfully, this new research might help experts understand how to help the moths’ survival.

“Knowing that they use vision as one part of the sensory arsenal that they use to guide their navigation may inform protection approaches with respect to light pollution, for example, when the moths get trapped in cities,” Adden told the outlet.