The Kori bustard (Ardeotis kori) is a large bird bird found only in Africa. In fact, the male of this species may be the heaviest living animal capable of flight. Like most bustards, Kori bustards are ground-dwelling birds and have to face many of Africa's myriad of formidable terrestrial predators.
The Kori bustard is cryptically colored, being mostly grey and brown, finely patterned with black and white coloring. The upper parts and neck are a vermiculated black and greyish-buff color. The ventral plumage is more boldly colored, with white, black, and buff. The crest on its head is blackish in coloration, with less black on the female's crest. There is a white eye stripe above the eye. The chin, throat, and neck are whitish with thin, fine black barring. A black collar at the base of the hind-neck extends onto the sides of the breast. The feathers around the neck are loose, giving the appearance of a thicker neck than they really have. The belly is white and the tail has broad bands of brownish-gray and white coloration. Their feathers contain light-sensitive porphyrins, which gives their feathers a pinkish tinge at the base- especially noticeable when the feathers are shed suddenly. The head is large and the legs are relatively long. The eye is pale yellow, while the bill is light greenish horn colored, relatively long, straight, and rather flattened at the base. The legs are yellowish. The feet have three forward-facing toes. Females are similar in plumage but are much smaller, measuring about 20-30% less in linear measurements and often weighing 2-3 times less than the male. The female is visibly thinner-legged and slimmer-necked. The juvenile is similar in appearance to the female but is browner with more spotting on the mantle, with shorter crest and neck plumes. Male juveniles are larger than females and can be the same overall size as adult males but tend to be less bulky with a thinner neck, shorter head crest, paler eyes, and a darker mantle.
Kori bustards are African birds, living within two separate areas of distribution. These are the southwest of the continent, near the Horn of Africa, covering parts of Ethiopia, Kenya, and Tanzania; and the other one in the far south, stretching across all of Botswana and Namibia, some parts of Zimbabwe, and reaching South Africa. The ideal environment for these birds is areas with short grass and dry, sandy soil. Kori bustards are found in savannas, grasslands, and scrublands. In addition, they can sometimes visit agricultural fields with scattered trees and wheat growth.
Kori bustards usually live in the same place as long as there are available sources of food and water. Generally, these bustards occur alone or in small flocks, rarely - in larger groups. Kori bustards are diurnal. They usually search for food in low bushes or trees during the daytime hours, spending the greater part of their time on the ground. Kori bustards are extremely shy and cautious birds. Normally, they are not afraid of humans. But once threatened or alarmed, they immediately couch or run. Kori bustards walk with the identifying slow and hesitant gait. When spotting an intruder, they quietly back away in order to remain unnoticed. As a large and heavy bird, Kori bustards do not tend to fly, preferring to run when necessary. When pushed forward, they usually run, making heavy wing-beats. Kori bustards are usually silent but, when alarmed, both sexes emit a loud growling bark. This is described as a 'ca-caa-ca' call, repeated several times for up to 10 minutes. This call carries long distances. This call is most often given by females with young and males during agonistic encounters. Chicks as young as two weeks will also emit this alarm call when startled. The male's mating call is a deep, resonant 'woum-woum-woum-woum' or 'oom-oom-oom' or 'wum, wum, wum, wum, wummm'. This call ends with the bill snapping which is only audible at close range. Outside of the breeding display, Kori bustards are often silent. Only females may emit a high alarm call or a deep 'vum' on takeoff.
Kori bustards are omnivores, consuming food of both animal and plant origin. These birds primarily feed on meat, using insects, small species of mammals, reptiles, and other birds. They supplement their diet with seeds, berries, and, occasionally, gum of the Acacia tree.
Kori bustards have polygynous mating system, where each male mates with a number of females. During the breeding season, which lasts from the middle of March to August, males gather into special group called "lek", performing displays in mornings and evenings, in order to attract receptive females. The courtship displays of the males are impressive and elaborate, successfully advertising their presence to potential mates. The males hold their heads backward, with cheeks bulging, the crest is held erect, the bill open and they inflate their gular pouches, forming a white throat "balloon". During this display, the oesophagus inflates to as much as four times its normal size and resembles a balloon. They also puff out their frontal neck feathers which are splayed upwards showing their white underside. The white may be visible up to 1 km (0.62 mi) away during display. When displaying they stride about with their necks puffed out, their tail fanned and their wings planed and pointed downward. They also emit a low-pitched booming noise when the neck is at maximum inflation and snap their bills open and shut. Several males dispersed over a wide area gather to display but usually one is dominant and the others do not display in his presence and move away. The displaying males are visited by the females who presumably select the male with the most impressive display. Kori bustards don't construct nests; they simply make a small shallow recess in the ground, where the females lay 1-2 eggs, incubating them for about 23-24 days. The eggs of Kori bustard are pale olive, covered with brown markings. Newly hatched chicks are precocial. The hatchlings are generally cared by their mother, rarely - by the father. At the age of around 4-5 weeks, the chicks fledge, though the female stays with her offsprings until the following year. Kori bustards become reproductively mature at 2 years of age.
Along with many other animal species, this bird currently suffers from the loss of its natural habitat as a result of farming and livestock grazing. Kori bustards are also threatened by high-voltage power lines, which are potentially dangerous for flying birds. In addition, they attract hunters for their meat as well as feathers, which are used by the American fly fishing trade.
According to the IUCN Red List, the total population size of the Kori bustard is unknown, though the birds are known to be common in some areas of their range. In South Africa, for example, the estimated population of Kori bustards varies from 2,000 to 5,000 individuals. Currently, this species is classified as Near Threatened (NT) on the IUCN Red List and its numbers today are decreasing.
The Kori bustard can occasionally be seen with Carmine bee-eater perched on its back; these two often cooperate with each other, feeding together. When foraging, the bustard stirs up insects, which are immediately captured by the Carmine bee-eater. The latter, in turn, helps the Kori bustard escape predators.