Searching for carrion, their main source of food
These large black birds are often seen hovering ominously in the sky, searching for carrion, which is their main source of food. In common with most vultures, their heads are bare, and the color of the skin on their heads is the best way to identify them.
The turkey vulture (zopilote cabecirojo; Cathartes aura) and the black vulture (zopilote negro; Coragyps atratus) are both common countrywide below 2000m and occasionally higher. The turkey vulture soars with V-shaped wings and has gray primary feathers, giving the wings a two-toned appearance from below, and has a red head. The black vulture has flatter, broader wings with a whitish patch at the base of the primaries, and a black head. (Young turkey vultures also have blackish heads). turkey vultures soar fairly low and can detect carrion by scent, while black vultures soar higher and look for carcasses visually, which is why the latter are more common over open areas and near towns, while the turkey vultures are seen over forests. The turkey vultures watch for other vultures descending food, and when both species are present at a carcass, the stockier heavier black vultures will force the turkey vultures away unless there in an excess of meat.
The lesser yellow-headed vulture (zopilote cabecigualdo; Cathartes burrovianus) looks like a small turkey vulture with a yellow head but is much less common. The king vulture (zopilote rey; Sarcoramphus papa) is the largest vulture and is easily identified by its off-white body and legs, black primary wing feathers and tail, and a wattled head colored with various shades of orange-yellow. It is most frequently seen in Corcovado, though it lives almost countrywide in small numbers.