Oxpeckers
It is commonly said that Oxpeckers perch on an animal's body and eat insects. But it does not seem to be doing all that good, as I have seen them pecking at blood in animal wounds.
This is a red-billed oxpecker. The photo does not show it well, but the tip half of the beak is reddish.
This is a yellow-billed oxpecker. This one has a yellow beak. The animal is an eland, a large antelope.