Most insects have no trouble moving around when the moon is bright, but darker nights can make nighttime navigation a bit more difficult. African dung beetles, however, have apparently found a workaround — the Milky Way. A recent study from researchers in Sweden and South Africa found that on moonless nights, dung beetles use the stars to help orient themselves, a rather surprising tactic for a creature that spends so much time with its nose to the ground. In fact, scientists say these findings are the first evidence of any insect having celestial navigation capabilities.
Researchers made this discovery after examining the different ways in which the beetles push their balls of dung. Under normal conditions, the insects store their dung balls in a secure location by moving it along a straight path. As the study notes, the beetles were able to replicate this behavior under moonlit nights and on dark nights when only the Milky Way was visible, but struggled to navigate under more overcast conditions. In planetarium tests, they performed equally well under a fully starlit sky and one showing only the Milky Way. When researchers strapped visors to their heads to block out the sky entirely, they were completely disoriented.
A first for the insect kingdom
Thus far, only birds, humans, and seals have been known to use celestial navigation techniques, but these findings raise the possibility that other nocturnal insects may rely on the stars, as well. Yet lead researcher Marie Dacke of Lund University in Sweden cautions against extrapolating her results too far, noting that dung beetles are unique in their reliance upon straight paths to collect dung.
"Dung beetles are known to use celestial compass cues such as the sun, the moon, and the pattern of polarized light formed around these light sources to roll their balls of dung along straight paths," Dacke said. "Celestial compass cues dominate straight-line orientation in dung beetles so strongly that, to our knowledge, this is the only animal with a visual compass system that ignores the extra orientation precision that landmarks can offer."