Distinguished from Yellow-billed Oxpecker by its all-red bill, the bare yellow skin around the eyes and the dark (not pale) rump.
Juvenile has a predominantly black bill, is overall darker than juvenile Yellow-billed Oxpecker, and has a dark (not pale) rump.
Savanna, in association with game and cattle. Usually in flocks.
A scolding 'churrrr' and a hissing 'zzzzzzist'.