Sergey Gorshkov / Red-billed Oxpecker (Buphagus erythrorhynchus) trio on White Rhinoceros (Ceratotherium simum), Sabi-sands Game Reserve, South Africa

Yva Momatiuk & John Eastcott / Cape Buffalo (Syncerus caffer) bull with Red-billed Oxpecker (Buphagus erythrorhynchus) pair, Masai Mara National Reserve, Kenya

Richard Du Toit / Hippopotamus (Hippopotamus amphibius) male with Red-billed Oxpecker (Buphagus erythrorhynchus) pair on back, Chobe National Park, Botswana

Tony Heald / Hippopotamus {Hippopotamus amphibius} with Red billed oxpeckers on head, Moremi Wildlife Reserve, Botswana

Mitsuaki Iwago / Cape Buffalo (Syncerus caffer) eyeing Red-billed Oxpecker (Buphagus erythrorhynchus), Serengeti National Park, Tanzania

Mitsuaki Iwago / Black Rhinoceros (Diceros bicornis) with Red-billed Oxpecker (Buphagus erythrorhynchus), Serengeti National Park, Tanzania

Richard Du Toit / Red-billed Oxpecker (Buphagus erythrorhynchus) on Impala (Aepyceros melampus) male, Kruger National Park, South Africa

Mitsuaki Iwago / Black Rhinoceros (Diceros bicornis) mother and baby with Red-billed Oxpeckers (Buphagus erythrorhynchus), Ngorongoro Crater, Tanzania

Richard Du Toit / Impala (Aepyceros melampus) with Red billed oxpecker (Buphagus erythorhynchus) searching for insects, Kruger NP, South Africa

Richard Du Toit / Impala with Red billed oxpecker on back, Kruger NP, South Africa

Richard Du Toit / Red billed oxpecker on Buffalo head, Kruger NP South Africa

Richard Du Toit / Red billed oxpecker looking for insects on Common zebra, Kruger NP, South Africa.