These sporty birds are Yellow Billed Oxpeckers that I photographed in the south-west Serengeti. Oxpeckers have a voluntary symbiotic relationship with some savanna animals and spend much of their time perched on giraffe, wildebeest, zebra, hippo, cape buffalo, and other savanna mammals. Non-mating birds sometimes even live and sleep on a host animal for extended periods. Oxpeckers feed on ticks, flies, and parasites, so both animals benefit from the relationship.