Red-billed oxpeckers travel around on herd animals and eat ticks and parasites living on the herd animal's skin. The birds get food, and the herd animals get pest control. Is this an example of commensalism, mutualism, parasitism, or predation

This is an example of mutualism. Mutualism is a type of symbiotic relationship where both species benefit from each other. In this case, the red-billed oxpeckers get food by eating ticks and parasites from the herd animals, while the herd animals get pest control, as the oxpeckers remove harmful parasites from their skin.