Diagram of the polarisation filter and changes to the ambient lunar polarisation pattern. (A) During the inbound journey, a linear polarisation filter was placed over the forager, rotating the overhead e-vector by ±45°. Panel depicts the positional measurements recorded during testing. Initial orientation routes were measured from the foraging tree release point (a) to when the polarisation filter was placed over each forager (b). Exit orientations were measured from the filter centre (b) to the forager’s exit location at the filter edge (c). Route directions under the filter (b°) were calculated from the forager’s initial route direction zeroed. Reorientations were measured from the forager’s exit location from the polarisation filter (c) to the forager’s path 1m after exit (d). Reorientation directions (c°) were calculated from the under-filter route direction zeroed. (B) Images of the sky and canopy cover at both nests. Photos were taken at the on-route midpoint between the foraging and nest trees. (C) Lunar phases denote the sunlit part of the moon’s surface and where this area is increasing (Waxing) or decreasing (Waning). The lunar phase cycle repeats every 29.5 days. moon images are public domain art accessed through wiki commons (https://commons.wikimedia.org/).

Circular distributions of headings during the original full moon conditions. In both conditions, testing occurs in the nights preceding the full moon (illumination > 80%) with the moon waxing. Circular plot shifts show the exit orientations of individual foragers from their initial headings while the reorientation represents the change in headings 1m after exiting the filter. Triangles denote the ±45° e-vector rotation. The arrow denotes the length and direction of the mean vector. (A) Nest 1 foragers, 5m from the nest (6.0m foraging route). (B) Nest 2 foragers, 2m from the nest (3.1m foraging route). n, number of individuals; Ø, mean vector; r, length of the mean vector.

Circular distributions of headings during (A) Waxing Quarter Moon, (B) Waxing Crescent Moon and (C) No Moon conditions. Circular plot shifts show the exit orientations of individual foragers from their initial headings while the reorientation represents the change in headings 1m after exiting the filter. Triangles denote ±45° e-vector rotation. The arrow denotes the length/direction of the mean vector. n, number of individuals; Ø, mean vector; r, length of the mean vector.

Circular distributions of headings during (A) Waning Full Moon, (B) Waning Quarter Moon conditions. Circular plot shifts show the exit orientations of individual foragers from their initial headings while the reorientation represents the change in headings 1m after exiting the filter. Triangles denote ±45° e-vector rotation. The arrow denotes the length/direction of the mean vector. n, number of individuals; Ø, mean vector; r, length of the mean vector.

Shift magnitudes for lunar phase conditions at Nest 1. Each circular plot shows the ±45° combined shifts for each condition. Triangles denote +45° e-vector rotation; data from –45° were mirrored and combined). The arrow denotes the length and direction of the mean vector. n, number of individuals; Ø, mean vector; r, length of the mean vector.

Circular distributions of M. midas headings during (A) Released Halfway, (B) Collected & Released Halfway conditions. Foragers in both conditions were tested at 2m from the nest with Released Halfway foragers having a long 6.0m vector and Collected & Released Halfway foragers having a 3.1m vector. Circular plot shifts show the exit orientations of individual foragers from their initial headings while the reorientation represents the change in headings 1m after exiting the filter. Triangles denote ±45° e-vector rotation. The arrow denotes the length and direction of the mean vector. n, number of individuals; Ø, mean vector; r, length of the mean vector.

Mean shift magnitudes, +45° and –45° combined, reported as percentages of the 45° e-vector rotation (100% = 45°). Vector data for solar polarised light is reported from Freas et al. 2017, Royal Society Open Science. Sun and moon images are public domain art accessed through wiki commons (https://commons.wikimedia.org/).