Every spring, billions of bogong moths emerge in southeast Australia, embarking on an impressive journey to the Australian Alps.
These 1-inch-long moths instinctively traverse around 600 miles from the hotter lowlands to the cooler caves located in the mountains.
Despite their remarkable navigation skills, scientists have long questioned how these tiny creatures find their way to their seasonal destinations.
Recent research published in the journal Nature sheds light on this mystery, revealing that bogong moths are capable of using the starry night sky as a navigational guide.
Eric Warrant, a professor of zoology at Lund University in Sweden and an author of the study, expressed astonishment at the moths’ abilities.
He noted, “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.”
While other species, including various birds and humans, have demonstrated the ability to navigate using stars, this talent had not previously been documented in insects for long-distance travel.
According to Andrea Adden, a postdoctoral researcher at The Francis Crick Institute in London and a contributor to the research, the bogong moths are the very first documented insects to utilize stellar navigation for extensive voyages.
To uncover this fascinating ability, researchers captured wild bogong moths and placed them in a flight simulator, designed to mimic natural flying conditions.
In this simulator, the moths were suspended on a thin tungsten rod, allowing them to flap their wings and turn freely as if they were in flight.
David Dreyer, a fellow researcher at Lund University, explained, “It can rotate freely; it can choose any direction it wants to fly to.”
To examine the moths’ navigation skills, researchers created a magnetic vacuum to disable their internal magnetic compass, thus focusing on their other navigational senses.
They projected an adjustable image of the night sky onto the simulator, experimenting with its rotation to observe the moths’ flying patterns.
The results were revealing: the moths consistently adjusted their flying trajectories in accordance with the movement of the sky image.
Conversely, when presented with a randomized and fragmented sky display, the moths became disoriented.
Dreyer remarked, “The animals were totally disoriented. That was, for us, like the final proof, more or less, that they actually indeed use the stars for navigation.”
In additional experiments, the researchers investigated the neural response of the moths by making a tiny window in their brains and measuring electrical impulses associated with the star projections.
The findings indicated that the electrical activity spiked at specific angles of the sky, while no significant response occurred with random sky arrangements.
Warrant pointed out that bogong moths have small pupils, likely allowing them to see only the brightest stars.
He suggested that the creatures may utilize the Milky Way as a navigational reference.
“They probably see the Milky Way much more distinctly and brightly than we do,” Warrant noted.
As they approach their eventual destination, the moths likely rely on their sense of smell, detecting odor compounds emanating from the caves, which Warrant described as akin to the scent of rotting meat.
After spending the summer in these caves, the moths eventually return to their origins where they hatched.
Ken Lohmann, a professor of biology at the University of North Carolina who was not involved in this research, praised the study’s compelling methods and careful controls.
He highlighted the remarkable aspect of the moths’ navigation skills despite their small brains, stating, “It just highlights the ingenuity of natural selection.”
The bogong moths are currently classified as endangered, having been added to the International Union for Conservation of Nature’s “red list” in 2021.
The implications of these findings extend beyond mere curiosity; understanding the moths’ use of visual navigation may aid in conservation efforts.
Adden mentioned the challenges posed by environmental changes, noting, “The moth population has been decreasing dramatically in numbers over recent years, especially with the drought and the bushfires that Australia had in 2020.”
She emphasized that insights into the moths’ navigation using vision could inform strategies to mitigate the impacts of light pollution, particularly when these creatures become entrapped in urban areas.
Overall, the discoveries regarding the bogong moths’ navigational prowess offer valuable information for both the scientific community and conservationists working to preserve this unique species.
image source from：nbcnews
