Dung Beetles Use the Milky Way for Orientation

Current Biology
Volume 23, Issue 4, 298-300, 24 January 2013

Marie Dacke [1, 2], Emily Baird [1], Marcus Byrne [2], Clarke H. Scholtz [3], Eric J. Warrant [1]

1 Department of Biology, Lund University, 223 62 Lund, Sweden
2 School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa
3 Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa

Highlights

African dung beetles orient to the starry sky to move along straight paths
The beetles do not orientate to the individual stars, but to the Milky Way

Summary

When the moon is absent from the night sky, stars remain as celestial visual cues. Nonetheless, only birds, seals, and humans are known to use stars for orientation. African ball-rolling dung beetles exploit the sun, the moon, and the celestial polarization pattern to move along straight paths, away from the intense competition at the dung pile. Even on clear moonless nights, many beetles still manage to orientate along straight paths. This led us to hypothesize that dung beetles exploit the starry sky for orientation, a feat that has, to our knowledge, never been demonstrated in an insect. Here, we show that dung beetles transport their dung balls along straight paths under a starlit sky but lose this ability under overcast conditions. In a planetarium, the beetles orientate equally well when rolling under a full starlit sky as when only the Milky Way is present. The use of this bidirectional celestial cue for orientation has been proposed for vertebrates, spiders, and insects, but never proven. This finding represents the first convincing demonstration for the use of the starry sky for orientation in insects and provides the first documented use of the Milky Way for orientation in the animal kingdom.

http://www.cell.com/current-biology/retrieve/pii/S0960982212015072

http://www.sciencedirect.com/science/article/pii/S0960982212015072