The dung beetle dance: an orientation behaviour?

Abstract

An interesting feature of dung beetle behaviour is that once they have formed a piece of dung into a ball, they roll it along a straight path away from the dung pile. This straight-line orientation ensures that the beetles depart along the most direct route, guaranteeing that they will not return to the intense competition (from other beetles) that occurs near the dung pile. Before rolling a new ball away from the dung pile, dung beetles perform a characteristic "dance," in which they climb on top of the ball and rotate about their vertical axis. This dance behaviour can also be observed during the beetles' straight-line departure from the dung pile. The aim of the present study is to investigate the purpose of the dung beetle dance. To do this, we explored the circumstances that elicit dance behaviour in the diurnal ball-rolling dung beetle, Scarabaeus (Kheper) nigroaeneus. Our results reveal that dances are elicited when the beetles lose control of their ball or lose contact with it altogether. We also find that dances can be elicited by both active and passive deviations of course and by changes in visual cues alone. In light of these results, we hypothesise that the dung beetle dance is a visually mediated mechanism that facilitates straight-line orientation in ball-rolling dung beetles by allowing them to 1) establish a roll bearing and 2) return to this chosen bearing after experiencing a disturbance to the roll path.

Figure 1. The circumstances that cause dance behaviour in dung beetles.

The percentage of beetles that danced under the following conditions: a) at the dung pile, just after making a ball and just before rolling, b) rolling into an obstacle (experiment 2), c) falling off a step (experiment 3), d) rolling off course in a curved tunnel (experiment 4, results from both the 1 m and 1.5 m diameter tunnels are represented with one bar as they were the same), e) 180° rotation with a view of the sky (experiment 5), f) 180° rotation with no view of the sky (experiment 5) and g) 180° reflection of the sun (experiment 6). Grey boxes indicate the results from the control conditions for experiment 2 (b), 3 (c) and 5 (d). Error bars indicate the standard error of the proportion.

Figure 2. The effect of rolling off course on dance behaviour.

The correlation between the angular deviation of dances performed by individual beetles in the 1 m and 1.5 m diameter semi-circular tunnels.