OXPECKERS [Ref]
The lives of oxpeckers are so linked to those of large, hoofed game or domestic cattle that in West Africa where game is scarce the birds depend on cattle, and their range is restricted accordingly. There the cattle are confined to the higher and more northern areas, free of tsetse flies, from Senegal to Northern Cameroon. Thus tsetse flies help to determine the limits of the oxpeckers' range.
Except for their nesting, which is in holes in trees, and their sleeping, most of their time is spent on the bodies of the larger herbivores. There they run about over the hides and legs of the beasts, like woodpeckers on a tree. They stay remarkably close to the animals, and even ride on them as they travel. The oxpeckers' food is largely ticks, which it gets from the hide of the animal by working over it with the side of its bill, shearing off the ticks with a scissorlike action of its mandibles. But when an animal has sores or cuts or scratches the oxpecker may peck into them, and eat flesh and blood of its host.
Correlated with this unusual and close relationship, a modification in the oxpeckers has taken place. There are only two species, both African, and they are dull-colored, modified starlings. The legs are stout, with curved, very sharp claws for clinging to the hides of animals, and the bill, very sharp at the tip, with the cutting edge of the mandible very sharp to aid in scissoring off ticks.
All the larger herbivores are attended by oxpeckers except the elephant and the hippo, but the favorite seems to be the rhino, and for this he's sometimes called the rhino bird as well as tickbird and oxpecker. The rhino gives the bird its food, and in return the bird provides a service of a value difficult to evaluate. It acts as a sentinel and may warn the rhino of the approach of hunters, for which habit it is execrated by sportsmen.
It would seem that such relationships could have developed only where the supply of big game was large. With the introduction of cattle and other domestic animals it was natural the oxpecker should turn its attention to them. Here the question arose as to the attentions of the oxpeckers being harmful or otherwise to the herds. Mr. R. E. Moreau, formerly of the East African Research Station at Amani, has investigated the problem. He finds that white men who own herds tend to consider the oxpecker a nuisance; Africans tend to consider it beneficial and some African cattle owners object to having the birds killed; the beasts themselves tolerate the birds.
There is the possibility on the one hand of oxpeckers spreading certain cattle diseases that are mechanically transmitted, and on the other hand they may help reduce disease by eating ticks, the vectors of certain diseases. Of course dipping the cattle takes care of ticks on them, and here we see another indirect effect of civilization on bird life. When cattle have been dipped the oxpeckers disappear from the herd. Perhaps it is because there is no longer food for them there; perhaps they get enough of the poison dip left on the beasts' hair to be lethal.