Intra- and intersexual interactions at breeding burrows in the horned beetle, Coprophanaeus ensifer

Coprophanaeus ensifer is a large horned beetle in which, in contrast to many other horned beetles, both males and females possess a long head horn. The species is a carrion feeder and has a developed nesting behaviour including provisioning the nest with larval food. Interactions between individuals at breeding burrows were observed in terraria. Both intra- and intersexual fights were common. In males fighting time was correlated with horn size. Although the horn size distribution of males was platykurtic there was no clear evidence of dimorphism in behaviour. Males tried to copulate with all females but only a few attempts with large females resulted in a copulation. All males actively tried to copulate but larger males were more successful. In each experiment individuals starting nesting behaviour were usually the largest ones. The significance of body and horn size is discussed with special emphasis on female horns and fighting behaviour.