Dung pad residence time covaries with male morphology in the dung beetle Onthophagus taurus

1. The immigration and emigration behaviours of Onthophagus taurus were inv estigated in a combination of field and laboratory experiments to examine p atterns of dispersal in this species. 2. On average, the mean proportion of major males immigrating to baited pit fall traps decreased significantly with time. In contrast, the mean proport ion of minor males and females did not change with time. 3. The time taken to emigrate from a dung pad differed significantly among major males, minor males, and females. This difference arose because major males spent a significantly shorter period of time residing within the dung pad. On average, more than 50% of major males had emigrated from the dung pads after 30 h, some 4 h earlier than minor males and females. 4. When the effects of body size were controlled, major males with longer h orns were shown to have longer wings. Because major males spend more time i n flight, longer wings may be an adaptation to more frequent dispersal. Alt ernatively, longer wings in major males may compensate for the production o f aerodynamically costly horns.