Sheathbills: Chionidae

Sheathbills vary in size from 13.4 to 16.1 inches (34 to 41 centimeters) in length and from 16 to 27 ounces (450 to 760 grams) in weight. They have plump bodies, short legs, and short conical, cone-shaped, bills with a horny sheath covering the upper bill. Sheathbills also have unusual featherless patches on the face covered with wart-like bumps called caruncles (KAR-un-kulz). The rest of the sheathbill body is covered with white feathers. Pale-faced sheathbills have a greenish sheath on the bills and pink caruncles, whereas black-faced sheathbills have black bill sheaths and black caruncles. Males are larger than females in the sheathbills, generally weighing about 15 percent more. Males also have larger bills and larger sheaths. Adult birds have more caruncles on their faces than younger birds. Older birds also have spurs on their wings which they use for defense and in fights.