Little Known Facts About the King Vulture

Several articles about the king vulture have repeated the same facts about this bird. We have compiled the following information based on existing literature and personal experience. Perhaps you will learn something about the king vulture that you never knew before.

King vulture landing on a perch. Photo: Vigner Lozano

The king vulture is the largest and most dominant vulture in most of its range

The king vulture (Sarcoramphus papa) is the most dominant scavenger in most of its range except in a small region where its range overlaps with that of the Andean Condor (Vultur gryphus). The king vulture’s range does not overlap with the California condor’s range.

In most of its range in the Americas, the king vulture (7.5 lb) occurs alongside smaller vultures, including the greater yellow-headed vulture (3.6 lb) and lesser yellow-headed vulture (3.4 lb), turkey vulture (3.3 lb), and black vulture (3.5 lb). The king vulture is about twice as big as other vultures in the Americas.

King vultures lose their dominance in a small region of northwest Peru and southwest Ecuador region, where they overlap with the Andean condor (~27 lb).

Most king vultures live in the tropical rainforest

Most king vultures live in the tropical rainforest of Brazil, Peru, Colombia, Ecuador, Bolivia, Central America, and Southern Mexico. King vultures are well adapted to find food under the forest canopy and along meandering rivers. Using their perhaps limited sense of smell and monitoring the activities of other scavengers, the king vulture can find small carcasses on the floor of dense tropical forests.

Although less common, the king vulture also lives in the savannah habitat and semi-open deciduous forest of northwest Peru, Paraguay, and the fringes of the Amazon basin.

The king vulture generally avoids disturbed habitats such as agricultural land and large areas with cattle ranches. However, it has become a regular consumer of livestock carcasses in parts of its range.

The king vulture is nearly mute

When they are young, king vultures make a variety of noises and even whistles. As they grow older, they lose the ability to make noises. 

Adult king vultures do not have a “box voice” in the syrinx, enabling birds to produce sound without vocal cords.

Adult birds do make croaking and bill snapping noises when they show aggression towards other individuals. They have also been heard making croaking and bill snapping noises as an aggressive reaction to biologists approaching their nests.

How long do king vultures live?

King vultures have long lifespans. All information about king vulture lifespan comes from birds kept in zoos. 

Data published by the National Geographic Society indicates that:

  • A king vulture kept in a zoo lived to be 30 years of age by the time it died. 
  • A separate king vulture lived to be 47 years, also in a zoo.

It is a well-known fact that animals in captivity tend to live longer. The animal aging and longevity database “Anage” estimates that the average lifespan of a king vulture in captivity is 40 years.

King vultures inspect a large carcass before descending to the ground. Photo: Luis Urruena.

How many king vultures are there?

The estimated number of king vultures calculated using two separate approaches varies substantially. 

Partners in flight estimate that the maximum number of king vultures in the wild is less than 50,000 individuals (A. Panjabi in litt. 2008).

Ferguson-Lees et al. (2001) suggest that the number of king vultures in the wild is likely between 1,000 to 10,000 individuals, of which 670-6700 are mature birds. 

What is the king vulture’s function in the ecosystem?

King vultures feed on carrion and play an important role in the ecosystem by helping with the process of biodegradation of potentially harmful carcasses. Biodegradation is typically carried out by microorganisms but is aided by scavenger animals.  

Biodegradation is the transformation of biological material into products such as water, carbon dioxide, and organic material. In this context, biodegradation can be interpreted as the transformation of potentially harmful biomass into environmentally safer components such as water, carbon dioxide, and organic material.

King vultures help accelerate the process by reducing the potential for carcasses of sick animals to become vectors of disease. King vultures consume many dead animals that would otherwise need to be incinerated.

The king vulture’s cleaning services are essential in places where dead animals would rot and smell for weeks, potentially spreading disease.

The key role of the king vultures in the scavenger community

The role of a king vulture in the scavenger community is to rip open the thick skin of large mammals. Smaller vultures would only have limited access to part of the carcass without the king vulture’s strength to rip open carcasses. 

A king vulture’s skull shape, beak morphology, and strength enable it to tear, rip, and make holes in key parts of a carcass in order to access internal organs and muscles.

Once the carcass is open, the king vulture consumes as much as it can and leaves plenty of food for smaller scavengers. 

Among the scavenger bird community in the Americas, king vultures are defined as rippers, the turkey vulture, yellow-headed vultures as scrapers, and the black vulture as gulper.

What are the threats to king vultures?

Loss of habitat is the main threat to the king vulture. The loss of habitat for wildlife reduces the number of carcasses available to the king vulture.

The king vulture is not as susceptible to poisoning as other bird species. King vultures are retiring scavengers who avoid contact with humans. 

Despite eating domestic animals, most of its diet in most of its range consists of wild species. As a result, they are less prone to poisoning than other vultures. 

Within the king vulture’s range, illegal hunting is a problem. Local people who admit to shooting a king vulture said their main motivation was curiosity. A large bird with such striking plumage makes for an impressive trophy. 

The king vulture does not have a reputation of being a threat to domestic animals.

Is the king vulture endangered? 

Despite the decline in the king vulture population across its range, this vulture is not listed as threatened or endangered due to its widespread distribution.

In spite of its declining population trend, changes in numbers and habitat destruction are not occurring at a rate that would justify listing the king vulture as a threatened species.

According to Birdlife International, the king vulture is estimated to occur in a range of 20,000 square kilometers, and the decline of its population is less than 30% in ten years, which places the king vulture under the category of least concern.

The smaller black vultures (left) rely on, the larger and stronger king vulture (right) to open up carcasses with thick skin and access the carcass’s interior. Photo: Carlos Riveiro.

It is a puzzle why the king vulture’s head, neck, and carbuncle are so colorful

Most birds evolve colorful feathers, ornate appendages, and colorful bare parts (beak, legs) to respond to sexual selection. Females chose more colorful males that, over time, resulted in offspring that were more and more colorful offspring as adults. In most cases, though, only the male has the colorful plumages and appendages.

Male and female king vultures have the same neck, head, and carbuncle (brightly colored bulging skin in the head), disproving the idea that sexual selection is the cause of the king vulture’s colorful head and neck pattern.

An alternate theory is that birds use their head and neck colors to communicate their state of health and breeding conditions.

According to another theory, the color of king vultures’ heads and necks may indicate their social status. Young birds have plain, dark heads and are at the bottom of the hierarchy. Older birds have a brighter color on their head and neck and a more developed carbuncle and wattle; hence, they occupy higher social status.

These are the only theories that may help to explain the likely reasons for the king vulture’s bright and colorful head color and carbuncle pattern.

Does the king vulture use its sense of smell to find dead animals?

It is not entirely known if the king vulture has a well-developed sense of smell and if it uses it to find carcasses. Early observations of the king vulture’s natural history indicated its keen sense of sight. This observation has been repeated by many and has become a fact.

However, an experiment conducted in Costa Rica proved that the king vulture has a well-developed sense of smell and it uses it to find dead animals. 

The experiment consisted of placing dead animals on the forest floor of a dense tropical forest. The king vulture was the first to arrive at the carcasses, proving that the only way they were able to find the carcass was by using its sense of smell. 

The king vulture lives in forested areas where carcasses on the forest floor are not seen from the air. It would only make sense that the king vulture has at least a rudimentary sense of smell that it uses to find its food. 

A fledgling king vulture takes 5 years to attain the adult plumage 

From the time it leaves the nest with juvenile blackish plumage, the king vulture takes up to 5 years to attain its adult plumage.

In a seemingly orderly process, young king vultures undergo a continuous molt that replaces their blackish plumage with white. The young birds first replace the feathers on their breasts and bellies with white ones. Then it continues to replace the feathers on the back to complete the black and white plumage of the adult.

Other related vultures such as the Andean condor (Vultur gryphus) and California condor (Gymnogyps californianus) also go through a long molting process to attain the adult plumage. 

As for the changes in plumage, the Andean condor changes from dark brown to black, while the California condor changes only from shades of black. Therefore, changes in plumage are not as obvious as those in the king vulture’s black and white plumage. 

The king vulture has an unresolved genealogy

Besides other vultures in the Americas, it is unknown what birds are close relatives of the king vulture.

First of all, the king vulture and vultures of the Old World (Africa, Asia, and Europe) are unrelated. 

King vultures share morphological and behavioral traits with falcons and storks. Some of these traits are faint and somewhat obscure, suggesting that king vultures, storks, and falcons split from some common ancestor many years ago.

More recent molecular studies using advanced techniques have only opened more questions than provided answers. We know for certain that the king vulture is a close relative of the smaller black-plumaged vultures of the Americas, the Andean condor, and the California condor.

The king vulture was originally given the scientific name of the Andean condor

Taxonomist Carl Linneus (1758) first described and gave the name of “Vultur gryphus” to the king vulture. Vultur gryphus is the current scientific name of the Andean condor.

Linnaeus described the king vulture to science based on two birds kept in a zoo in London. Subsequently, the king vulture was named “Vultur papa.” 

In 1805 taxonomist C. Dumeril changed the king vulture’s name to the current name Sarcoramphus papa.

Facts about the king vulture’s basic biology are poorly known

Despite its size, appearance, and huge range, facts about the king vulture’s basic biology have been studied only sparingly. Most of what we know about this vulture comes from birds kept in zoos and a handful of nests in the wild. King vultures have a huge range and occur in low populations. Another problem is that they are secretive about king vulture nesting activities

A variety of demographic data are unknown in the wild, such as the number of adults and juveniles, birth rates, productivity, survival rates, mortality, and lifespan.

This information about the king vulture will help understand the status and threats to the species and whether any conservation actions need to be taken.

King vultures fly high and monitor other vultures below

King vultures fly higher than smaller vultures. Doing so monitors the activities of turkey vultures (and other cathartic vultures) and black vultures. 

King vultures see the smaller vultures below from a vantage point, usually above 500 feet, to determine whether they are flying in a certain direction or congregating at a particular spot. The smaller vultures’ activities are likely to indicate that they have discovered a carcass. 

The king vulture flies in the direction where all the other vultures are heading, or if it sees vultures congregated, it descends at tremendous speed, making a booming sound. The king vulture gets access to the carcass first, regardless of whether it is the last to arrive.

To cool off, king vultures defecate on their own legs

A king vulture deliberately defecates on its own legs, making them white. Ornithologists suggest two possible reasons for this:  

To keep cool, king vultures poop on their legs to release heat. To transform from a liquid to a gaseous state, water molecules must first absorb heat energy. As the viscous liquid poop evaporates and dries, it absorbs heat from the bird’s legs. 

A king vulture may also use its own poop as an antiseptic. The digestive juices in their stomach kill harmful bacteria. The vulture’s poop also contains traces of the digestive juices; hence poop acts as an antibacterial.   By defecating on their legs, king vultures keep their legs clean from bacteria they collect from walking on rotten carcasses.