Hidden inside the giraffe's fur lies a multitude of ticks and parasites that the Oxpecker can feast on.
The yellow-billed Oxpecker can eat more than 100 ticks or 13,000 larvae every day. They also feed on blood and have been known to peck at the wounds of large mammals.
The extraordinary scene in the Serengeti was captured by Billy Dodson, from Williamsburg, Virginia, who travels to Africa twice a year to capture the wildlife in the country's major game reserves.
"I was busy taking a picture of the giraffe's profile and didn't spot the bird straight away," he said. "I have never seen one perched on the lip of an animal like that before. It was extraordinary.
"Usually they ride on the backs of Africa's big mammals and eat the ticks and other insects that make a home in the fur and skin.
"But this one was cleaning around the mouth for some reason. It was only balanced there for about 10 seconds or so but the giraffe seemed to be cool with the whole thing.
"I think it appreciated the bird's efforts to get rid of the annoying insects."
The Yellow-billed Oxpecker measures up to seven inches long and is most commonly found across the Savannah areas of West Africa.
The bird is a co-operative breeder - which means only one pair within a large group will breed, the other members help to make the nest.
Nests are usually found in tree holes and are lined with hair plucked from large mammals like buffalo, giraffe and warthog.
