Jaymi Heimbuch / Yellow-billed Oxpecker (Buphagus africanus) picking parasites off of Cape Buffalo (Syncerus caffer), Masai Mara, Kenya

Neil Aldridge / Yellow-billed oxpecker (Buphagus africanus) perched on the back of an African buffalo (Syncerus caffer) on the banks of the Chobe River, Chobe National Park, Botswana.

Neil Aldridge / Warthog (Phacochoerus africanus) with a Yellow-billed oxpecker (Buphagus africanus) on its back, nuzzling its mother at a waterhole, Chief's Island, Okavango Delta, Botswana.

Richard Du Toit / Greater kudu (Tregalaphus strepsiceros) covered in Yellowbilled oxpeckers (Buphagus africanus) rear view, Kruger National Park, South Africa.

Pal Hermansen / Yellow-billed oxpecker (Buphagus africanus) on African buffalo (Syncerus caffer), Masai Mara, Kenya

Shin Yoshino / Yellow-billed Oxpecker (Buphagus africanus) trio sitting on Cape Buffalo's (Syncerus caffer) head, Kenya

Mitsuaki Iwago / Hippopotamus (Hippopotamus amphibius) with Yellow-billed Oxpecker (Buphagus africanus), Serengeti National Park, Tanzania

Sharon Heald / Yellowbilled oxpecker {Buphagus africanus} on Zebra Moremi WR, Botswana, Africa

Jabruson / African buffalo with Yellow billed oxpecker. DR of Congo (formerly Zaire) Odzala NP

Denis-Huot / Impala (Aepyceros melampus), and Yellow-billed oxpeckers (Buphagus africanus) Masai-Mara game Reserve, Kenya.

Denis-Huot / Black rhino (Diceros bicornis), with Yellow-billed oxpeckers (Buphagus africanus) sitting on back and feeding on insects, Masai-Mara Game Reserve, Kenya

Ingo Arndt / Cape Warthog (Phacochoerus aethiopicus) adult male / with Yellow-billed Oxpecker (Buphagus africanus) adult sitting on head and calling, Masai Mara National Reserve, Kenya