Dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) compete intensively for dung resources, and most species forage in the understory. Here, we describe the unique behavior of one dung beetle species, Canthon aff. quadriguttatus (Olivier), associated with two species of monkeys from Peru. We observed this beetle species on the genital and anal regions of the brown titi monkey, Callicebus brunneus (Wagner), and subsequently falling with dung as the monkeys defecated. The same association was also observed with the bald-faced saki monkey, Pithecia irrorata irrorata (Gray). Using the " sit and wait" at the source behavior, C. quadriguttus may arrive first at the dung resource, possibly out-competing other dung beetle species. This paper is the first report of this behavior for C. aff. quadriguttatus on the brown titi monkey and bald-faced saki monkey from southeastern, Amazonian Peru. We discuss this behavior in the context of competition and resource partitioning, and also speculate as to why C. aff. quadriguttatus has been found on both monkey species.
