Yellow-billed Oxpecker (Buphagus africanus) photo
A feeding adult Yellow-billed Oxpecker.
These birds use a scissoring action to "comb" through the fur of their hosts to remove ticks and other ectoparasites. However they also pick at wounds to encourage bleeding and mammalian blood probably comprises a significant part of their diet!
Image taken in a low evening sun as we were returning to camp.