The King vulture is the most brilliantly colored New World vulture, with varying hues ranging from blue and purple to red or orange on its head. Its wing span can be as much as six feet, and the bill is more curved than with other species of vulture. Males and females look the same. Its more powerful features, for the purpose of feeding from the toughest animal carcasses, have given it its name: its larger size, brilliant color, and adapted features. Other birds treat the King vulture as the king, for example, when it flies in, other birds will stop feeding and let it eat.
King vultures live in the south of Mexico and throughout South and Central America to northern Argentina. Mainly frequenting humid tropical forests, they may sometimes be seen in more open areas like savannahs and grasslands. These birds prefer undisturbed forests inhabited by large mammals.
King vultures do not gather in large groups but remain in family units. They mostly stay out of sight, perched high up in the canopy, or they are flying about and soaring high above the ground looking for food. They do not migrate, remaining within the same area all year long. They are a diurnal species and much of their time is spent basking in the sun and saving their energy, sometimes preening their wing feathers. King vultures, unlike some other vulture species, have a poor sense of smell, relying on other vultures to locate prey, then descending to join in the feeding. These birds are very rarely aggressive, usually backing down instead of fighting. Due to their large bodies and wings, they totally depend on air currents for their flight, and avoid flapping their wings unless they really have to. King vultures do not have a voice box (a syrinx) or the muscles needed to make it work. They can make very low croaks. During breeding they will give warning sounds when something approaches their nest.
King vultures are monogamous and their pair bonds last for life. They are often seen perching high in trees under cover, or soaring very high up in the sky. As a result, their courting ritual is only seen in captivity, being a display where both birds walk around on the ground in circles while they flap their wings. They make loud snorting and wheezing noises during mating. Breeding usually takes place during the dry season. These birds are solitary and so do not gather in big colonies to nest. Instead of building nests, they lay their eggs in a stump or the hollow of a rotting log or a crevice in a tree. A single egg is laid and incubation lasts for around 55 to 58 days, with both parents regularly taking turns. Chicks are naked when they hatch but very soon acquire pure white down. The parents bring food to them in their claws, but also feed their chick by regurgitation. Young fledge at 3-4 months, but remain dependent on their parents until they are eight month old and may stay close to them for two more years. At three to four years of age a chick has developed all its plumage and other features. Females become mature at around 5 years of age, and males at around 7 years of age.
Although King vultures are not listed universally as endangered, populations are decreasing as a result of habitat destruction. They will not be able to survive if the forests where they live disappear.
The IUCN Red List reports the total King vulture population size as 1,000-10,000 individuals, approximately equating to 670-6,700 mature birds. However another study suggests there are fewer than 50,000 individuals in total. Overall, currently King vultures are classified as Least Concern (LC), but their numbers today are decreasing.
King vultures have an important role in the ecosystem in which they live. They usually find dead animals first and immediately begin to eat the rotting remains. As with all scavengers, their actions are important to keep the environment free of dead and decomposing animals, which may help reduce sources of disease.