Bull Ants Navigate Nighttime Foraging Using a Lunar Compass

A bull ant species continues to navigate after sunset using an innate lunar compass. By tracking the moon’s position and applying “time compensation,” the ants can travel between nest and food throughout the night without daylight.

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Researchers captured foraging ants, placed some in dark boxes and others in transparent boxes, then released them at a new site after several hours. Ants kept in darkness for a period long enough for the moon to move deviated from the correct path, indicating reliance on lunar position. The study also found that ants combine lunar cues with terrestrial and solar references at dawn and dusk to maintain navigation when moon visibility changes.

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The work was led by entomologist Cody Freas of the University of Toulouse and published in *Current Biology*. Rodolfo da Silva Probst, an entomologist at the University of California, Davis, provided commentary.

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The ants appear to keep an internal estimate of elapsed time since leaving the nest, allowing them to predict the moon’s azimuth at any moment. This mirrors early human navigation using celestial bodies. Simultaneous use of multiple cues lets ants compensate when any single cue fails.

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Understanding this lunar navigation may reveal how other nocturnal insects orient themselves. With over 12,000 ant species worldwide, the findings could guide future research into diverse ecological niches and navigation strategies.

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Cody Freas said the discovery fills a gap in knowledge of nocturnal ant navigation and highlights the ants’ reliance on multiple cues for reliable foraging. The team noted that the lunar compass works alongside terrestrial and solar references, enabling consistent navigation throughout the lunar month. Probst suggested that studying additional nocturnal ant species could uncover further navigational adaptations.

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Rodolfo da Silva Probst expressed surprise at the ants’ ability to compensate for the moon’s trajectory, calling the phenomenon “a little bonkers” and noting the difficulty of such navigation.

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• “It was an area where we didn’t really know what was going on” — Cody Freas, entomologist, University of Toulouse

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• “These ants use a lot of different cues at the same time, and that helps them in case one cue becomes unreliable.” — Cody Freas, entomologist, University of Toulouse

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• “This is just a little bonkers,” — Rodolfo da Silva Probst, entomologist, University of California, Davis

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• “They need to compensate for the trajectory of the moon. I mean, I don’t know how to do that.” — Rodolfo da Silva Probst, entomologist, University of California, Davis

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The article presents a single experimental account; no contradictory findings or missing data were identified.

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The authors propose extending research to additional nocturnal ant species to uncover alternative navigational strategies.

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