Head color and caruncles of sympatric Cathartes vultures (Aves: Cathartidae) in Guyana and their possible function in intra- and interspecific signaling

—The naked heads of Cathartes vultures are widely believed to be adaptations for temperature regulation and to reduce plumage fouling during carrion feeding. Bright head color and the elaborate pattern of caruncles on the head and neck skin have a likely function in intraand interspecific signaling. These integumentary characters have been difficult to study because of extensive postmortem color fading and shrinkage in museum specimens. Here I provide the first detailed description of head color and caruncles of the Greater Yellow-headed Vulture (C. melambrotus) from freshly collected specimens and provide comparative notes on sympatric populations of the Turkey Vulture (C. aura) and Lesser Yellow-headed Vulture (C. burrovianus) from Guyana.