Jen Guyton / Yellow-billed oxpecker (Buphagus africanus) sitting on the nose of an African buffalo (Syncerus caffer) in the Masai Mara Reserve, Kenya.

Jen Guyton / Common eland (Taurotragus oryx) male standing with Yellow-billed oxpecker (Buphagus africanus) on dewlap. Masai Mara Reserve, Kenya.

Tony Heald / African Buffalo (Syncerus caffer) with Yellow-billed Oxpecker (Buphagus africanus) feeding on parasites, Chobe National Park Botswana.

Sharon Heald / African buffalo (Syncerus caffer) with Yellow-billed oxpecker (Buphagus africanus) grooming, Chobe National Park Botswana.

Lisa Hoffner / Yellow-billed oxpeckers (Buphagus africanus) on neck of a Masai giraffe (Giraffa camelopardalis tippelskirchi) Masai Mara, Kenya.

Charlie Summers / Yellow-billed oxpecker (Buphagus africanus) female, Ngorongoro Crater, Tanzania, March.

Charlie Summers / Yellow-billed oxpecker (Buphagus africanus) female perched on vehicle, Ngorongoro Crater, Tanzania, March.

Charlie Summers / Yellow-billed oxpecker (Buphagus africanus) male outside nest hole, Ngorongoro Crater, Tanzania.

Charlie Summers / Yellow-billed oxpecker (Buphagus africanus) male, showing bright coloured beak, Ngorongoro Crater, Tanzania.

Richard Du Toit / Yellowbilled oxpecker (Buphagus africanus) on the back of Greater kudu (Tregalaphus strepsiceros) Kruger National Park, South Africa.

Richard Du Toit / Yellowbilled oxpecker (Buphagus africanus) group of three of Buffalo, back of Kruger National Park, South Africa.

Denis-Huot / Yellow-billed oxpecker (Buphagus africanus) cleaning a African buffalo (Syncerus caffer) Masai Mara Game Reserve, Kenya