A bulbul-sized olive-brown bird that sports a diagnostic all-red bill and a red eye surrounded by a fleshy yellow wattle. The juvenile lacks the bright bill and eye coloration. Small groups occur in savanna and farmland, where they require large wild ungulates and domestic stock to forage on; they clamber agilely over host mammals, gleaning ticks, mites, and other ectoparasites, and occasionally drinking host blood. As they fly between large mammals, they give a distinctive “tsik-tsik” call. The similar Yellow-billed Oxpecker differs from Red-billed Oxpecker by having a yellow bill base and pale rump and lacking an eye-wattle.