A bulbul-sized olive-brown bird that sports a diagnostic red-tipped yellow bill, a red eye without an eye-wattle, and a pale buff rump. The juvenile lacks the bright bill and eye coloration but shows the pale rump. 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 sizzling-crackle call. The similar Red-billed Oxpecker differs from Yellow-billed Oxpecker by having a red bill, a yellow eye-wattle, and a dark rump the same color as the remainder of the upperparts.