Complex sentence: A particular characteristic of many vultures is a bald head, devoid of feathers; if vultures had head feathers, they would become spattered with blood and other fluids when the vultures ate flesh from carcasses, and thus would be difficult to keep clean.
Split into simpler sentences: A particular characteristic of many vultures is a bald head, devoid of feathers. If vultures had head feathers, they would become spattered with blood and other fluids when the vultures ate flesh from carcasses, and thus would be difficult to keep clean.