Observation of a black-cheeked waxbill () cleaning a Kirk's dik-dik ().

The vast majority of interspecific interactions are competitive or exploitative. Yet, some positive interspecies interactions exist, where one (commensalism) or both (mutualism) species benefit. One such interaction is cleaning mutualisms, whereby a cleaner removes parasites from a client. In this note, we document the novel observation of a black-cheeked waxbill () appearing to clean a Kirk's dik-dik (), at the Mpala Research Centre in Laikipia County, Kenya. The purported cleaning took place for over one minute and is notable firstly for the dik-dik remaining still for the duration of cleaning and secondly for involving two species that are much smaller than those traditionally involved in bird-mammal cleaning interactions. Unfortunately, no further cleaning events were subsequently observed, raising questions about whether this record was opportunistic or a regular occurrence. Future observations may reveal whether this behavior is widespread and whether it involves other small passerines.