21 Collett T.S.

Zeil J. The selection and use of landmarks by insects.

22 Judd S.P.

Collett T.S. Multiple stored views and landmark guidance in ants.

23 Collett T.S.

Collett M.

Wehner R. The guidance of desert ants by extended landmarks.

24 Zeil J.

Hofmann M.I.

Chahl J.S. Catchment areas of panoramic snapshots in outdoor scenes.

25 Collett T.S.

Collett M. Memory use in insect visual navigation.

26 Collett T.S.

Graham P.

Durier V. Route learning by insects.

27 Durier V.

Graham P.

Collett T.S. Snapshot memories and landmark guidance in wood ants.

28 Harris R.A.

Graham P.

Collett T.S. Visual cues for the retrieval of landmark memories by navigating wood ants.

29 Lent D.D.

Graham P.

Collett T.S. Image-matching during ant navigation occurs through saccade-like body turns controlled by learned visual features.

30 Graham P.

Cheng K. Ants use the panoramic skyline as a visual cue during navigation.

31 Wystrach A.

Beugnon G.

Cheng K. Ants might use different view-matching strategies on and off the route.

32 Zeil J. Visual homing: an insect perspective.

33 Narendra A.

Gourmaud S.

Zeil J. Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi.

34 Narendra A.

Raderschall C.A.

Robson S.K.A. Homing abilities of the Australian intertidal ant Polyrhachis sokolova.

4 Dacke M.

Baird E.

Byrne M.

Scholtz C.H.

Warrant E.J. Dung beetles use the Milky Way for orientation.

35 Wystrach A.

Schwarz S. Ants use a predictive mechanism to compensate for passive displacements by wind.

If dung beetles take a celestial snapshot of the sky, their orientation behavior should not be influenced by an unnatural spatial relationship between the sun and the polarized light cues, and their performance should not be significantly different from their behavior when there is a natural relationship between these cues ( Figures 1 E and 1F). To test this prediction, we performed experiments in which the polarizer’s E vectors were unnaturally aligned with the ersatz sun’s direction and either the polarized light ( Figure 2 C) or the green light (the sun) ( Figure 2 D) was removed during the second roll. The beetles’ change of direction either was clustered around 0° when the polarized light was removed (p < 0.001: V test; n = 40; μ = 354.4° ± 57.3°; Figure 2 C) or was bimodally distributed along the 0°–180° axis (p = 0.002: V test, μ = 169.2° ± 42.7°, n = 40; Figure 2 D) when the green light was removed. The beetle’s orientation performance did not differ significantly from the tests in which the polarizer’s E vectors were in the natural spatial relationship to the green light (p = 0.146; Figure 1 E versus 2 C; p = 0.219; Figure 1 F versus 2 D; Mardia-Watson-Wheeler tests; Table S1 ). These results suggest that the beetles’ orientation behavior does not rely on a fixed spatial relationship of celestial cues but that they instead employ a “snapshot-based” strategy, similar to the manner in which path-integrating insects store a snapshot of terrestrial cues, i.e. landmarks and the panoramic skyline, for orientation []. Since the panoramic skyline can provide a stable reference even when traveling over long distances [], this could be an alternative simple mechanism for maintaining a straight line. However, dung beetles are disoriented when all celestial cues are hidden behind thick clouds [], suggesting that they ignore the panoramic skyline as an orientation reference. Unlike path-integrating insects that need to find their nest after traveling over long distances for long periods of time, dung beetles only need to move away from one location, the dung pile, in a straight line for a few minutes. Thus, a celestial snapshot appears to be a simple solution for their behavioral orientation task. However, this does not mean that path-integrating insects cannot also use a celestial snapshot strategy, but rather that they are only likely to use it in certain contexts. Ants, for example, seem to take some kind of snapshot of the celestial scenery just before they are passively displaced by wind []. This observation opens up the possibility that path-integrating insects can also use a celestial snapshot strategy for orientation.