Interactions between Red-billed Oxpeckers ( Buphagus erythrorhynchus ) and hippopotamus ( Hippopotamus amphibius ) in the Salambala Conservancy, Namibia

Oxpeckers (Buphagus spp.) play dual roles as mutualists and parasites of large mammals, primarily engaging in ectoparasite removal, with occasional instances of wound feeding. However, studies on their interactions with semi-aquatic species, such as hippopotamus (Hippopotamus amphibius, hereafter hippos), remain poorly documented. This study examined the behavioural interactions between oxpeckers and hippos stranded in an isolated pool formed by the drying of the Chobe River, Namibia (10–30 October 2024), which created a unique opportunity for close-range observations. We quantified oxpecker behaviour across hippo body regions and categorised feeding and non-feeding activities. Oxpecker activity varied significantly across body regions, with dorsal, cranial and lateral regions most frequently used. Non-feeding behaviour dominated overall activity, followed by wound feeding. Hippos showed high tolerance to oxpeckers, with very few rejection responses. These findings suggest that oxpeckers can exploit semi-aquatic hosts opportunistically when conditions permit, demonstrating behavioural flexibility and highlighting the ecological importance of temporary water bodies as interaction zones during dry periods.