Intraspecific female brood parasitism in the dung beetle <i>Onthophagus taurus</i>

1. Brood parasitism occurs when individuals parasitise each others’ investment into parental care, and has been documented primarily as an interspecific interaction. Intraspecific brood parasitism, in contrast, is often difficult to detect and quantify, and evidence for it is comparatively scarce. The present study documents the occurrence of intraspecific brood parasitism by females of the tunnelling dung beetle Onthophagus taurus, and investigates the contributions of two variables to the propensity of female brood parasitism: female body size and dung desiccation rate. 2. Female O. taurus were found to routinely utilise brood balls made by conspecific females as food provisions for their own offspring. 3. Contrary to expectations, large and small females did not differ in the likelihood of engaging in brood-parasitic behaviour. 4. Dung desiccation rate appeared to influence likelihood of brood parasitism. Females that were given access to rapidly drying dung were significantly more likely to detect and utilise brood balls produced by conspecific females. 5. While interspecific brood parasitism has been documented in dung beetles before, the present study is among the first to present evidence for intraspecific brood parasitism as an alternative reproductive tactic of female dung beetles. Results are discussed in the context of the evolutionary ecology of onthophagine beetles.