King Vulture

About the king vulture

The king vulture is a large bird of Central and South America and a member of the New World vulture family, Cathartidae. It is the only surviving member of its genus, Sarcoramphus, though fossil relatives are known. The bird is large and predominantly white, with a slight rose-yellow tinge to its body plumage, set against gray to black wing coverts, flight feathers, and tail, as well as a prominent dark neck ruff. Its head and neck are bald, an adaptation that keeps bacteria from carrion off its feathers and exposes the skin to the sterilizing effect of sunlight; the bare skin comes in shades of red and purple on the head, vivid orange on the neck, and yellow on the throat. A wrinkled, folded patch of skin on the head carries a noticeable golden crest above the orange-and-black bill, called a caruncle, which does not fully develop until the bird's fourth year. Its irises are white, ringed by bright red sclera, and unlike some other New World vultures it lacks eyelashes. Among New World vultures, the king vulture has, relative to its size, the largest skull and braincase and the strongest, sharpest-edged, hook-tipped bill.

Body length runs 67 to 81 cm (26 to 32 in), with a wingspan of 1.2 to 2 m (4 to 7 ft) and weight between 2.7 and 4.5 kg (6 to 10 lb), making it, apart from the two condor species, the largest of the New World vultures. There is little difference in size or plumage between males and females. Juveniles look quite different from adults: they have a dark bill and eyes and a downy gray neck that gradually turns orange, and their body plumage starts out slate gray, taking around five to six years to molt fully into adult white-and-black plumage. From a distance, dark-plumaged young birds can be mistaken for turkey vultures, while pale adults are occasionally confused with the wood stork, though the stork's long neck and legs set it apart on closer look.

There are two competing explanations for how the bird got the "king" part of its name. One holds that it refers to the way the king vulture displaces smaller vulture species from a carcass and eats its fill while they wait. The other traces it to Mayan legend, in which the bird served as a messenger between humans and the gods. It was also called the "white crow" by Spanish colonists in Paraguay.

Behavior and diet

The king vulture is a scavenger that often makes the first cut into a fresh carcass and displaces smaller New World vulture species once it arrives. Despite its size and bold coloring, it is relatively inconspicuous while perched, holding its head lowered and thrust forward, and it is relatively unaggressive at a kill. It generally lives alone or in small family groups rather than in the larger flocks formed by species such as the turkey vulture, though groups of up to 12 have been seen bathing and drinking together at a pool in Belize, and up to ten or so birds may gather at an especially large carcass. The bird soars for hours with minimal flapping, wings held flat with slightly raised tips, and can appear headless in flight from a distance; wing beats, when they occur, are deep and strong. It is non-migratory. To cool itself, the king vulture practices urohidrosis, defecating on its own legs. It lacks a voice box, but can produce low croaking and wheezing sounds during courtship and bill-snapping sounds when threatened. Natural predators are limited to snakes, which prey on eggs and young, and large cats such as jaguars, which can occasionally surprise and kill an adult at a carcass.

Breeding behavior is not well documented in the wild, and most of what is known comes from birds in captivity. Adults reach sexual maturity around four to five years old, with females maturing slightly earlier than males, and breeding occurs mainly in the dry season. The king vulture mates for life and typically lays a single unmarked white egg in a hollow in a tree, keeping the nest deliberately foul-smelling to deter predators. Both parents share incubation, which lasts 52 to 58 days, and if an egg is lost it is often replaced after about six weeks. Once the chick is about a week old, parents shift from brooding to standing guard. Chicks are semi-altricial, meaning they are covered in down and have open eyes at birth despite being otherwise helpless, and they become fully alert and able to beg and move around the nest by their second day.

Range and habitat

The king vulture inhabits an estimated 14 million square kilometers (5.4 million sq mi) between southern Mexico and northern Argentina. In South America it does not occur west of the Andes, apart from populations in western Ecuador, northwestern Colombia, and far northwestern Venezuela. It favors undisturbed tropical lowland forest, along with savanna and grassland near such forest, and is often seen near swamps or marshy ground within the forest. It generally lives below 1,500 m (5,000 ft), though it has been found up to 2,500 m (8,000 ft) east of the Andes and rarely as high as 3,300 m (11,000 ft). Within the forest, it occupies the emergent canopy layer or the space above it. In the Amazon rainforest it is typically outnumbered by the greater yellow-headed vulture, and in more open habitats by the lesser yellow-headed, turkey, and American black vultures.

Conservation status

The king vulture is listed as Least Concern (LC). Even so, numbers are described as decreasing, primarily due to habitat loss across its range.