Hooded crow foraging from dung pats: Implications for the structure of dung beetle assemblages

The occurrence of dung beetles in the diet of hooded crows (Corvus corone cornix L.) was examined in order to identify possible biases in predation that could influence the structure of local dung beetle assemblages. Pellets and gizzards collected in southern Ireland indicated that crows fed largely on insects between March and September, and dung beetles (particularly Aphodius prodromus (Brahm)) were the most common insects in the diet in March and April. An abundance of alternative prey items, including Carabidae and Curculionidae, may have protected late summer dung beetles from intense crow predation. Small beetles (i.e. Hydrophilidae ≤ 2mm body length) did not occur in the pellets or gizzards and may be ignored or avoided by foraging crows. Field observations and diet analyses suggest that crows prefer to forage from fresh equine dung rather than fresh cattle dung. We suggest that such predation biases could play a role in determining dung beetle assemblage structures at microhabitat (dung type) and macrohabitat scales.