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Ardeotis koriKori bustard

By Jill Bible

Geographic Range

Ardeotis kori lives throughout eastern and southern sub-Saharan Africa. There are two populations of Kori bustards, which are separated by the miombo woodland of Central Africa. The southern population is composed of the subspecies Ardeotis kori kori, which lives in parts of Zimbabwe, Botswana, Namibia, South Africa, Mozambique and southern Angola. The northeastern African population is composed of the subspecies Ardeotis kori struthiunculus, which inhabits parts of Somalia, Ethiopia, Sudan, Kenya, Uganda and Tanzania. ("BirdLife International", 2007)

Habitat

Kori bustards are found in dry habitats such as savannas, grasslands and semi-deserts. They are usually found near water sources and in areas with light tree cover, where they take shelter from the heat of the day. They do not inhabit entirely wooded areas. (Harrison, et al., 1997)

  • Range elevation
    700 to 2000 m
    2296.59 to 6561.68 ft

Physical Description

Kori bustards have large necks, crested heads, greyish brown backs, vermiculated grey necks and breasts, whitish bellies, black and white spotted patterns on the shoulder and sides of their necks, and black and white bars on their tails. Their bills, legs, feet, and eyes are all yellowish. The two subspecies are similar in appearance, but the southern subspecies is slightly larger and has a few differences in facial plumage. Kori bustards are easily distinguished from other bustards by their size, crest and lack of rufous on the hind neck. In flight, the distinguishing characteristic is grey speckled underwings without white markings. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

Kori bustards are the heaviest flying birds in Africa, with males weighing 10 to 19 kilograms and females weighing 5.5 to 5.7 kg. They range in length from 105 to 128 cm and have a wingspan of 75 to 76 cm in males and 60 to 65 cm in females. The sexes have similar plumage, although individual patterns may differ. Females are about half the size of males. Juvenile males have shorter head crests, paler eyes, and a darker mantle than adult males. Juvenile females also have shorter crests and paler eyes as compared to adult females. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

  • Sexual Dimorphism
  • male larger
  • Range mass
    5.5 to 19 kg
    12.11 to 41.85 lb
  • Range length
    105 to 128 cm
    41.34 to 50.39 in
  • Range wingspan
    60 to 76 cm
    23.62 to 29.92 in

Reproduction

During the breeding season, males perform elaborate displays, including deep booming calls, inflating their esophagus up to four times its usual size, erecting neck feathers, and fanning the tail to expose their white under tail coverts. These displays can last for several days and can be performed singly or in a group. Once a female has chosen a male, actual copulation is quite brief, lasting only a few seconds. (Hallager and Boylan, 2004; Harrison, et al., 1997)

Although the mating system of Kori bustards is unclear, males continue courtship dances after their initial copulation and do not invest in incubation and rearing, suggesting that they are polygynous. Courtship feeding in white-bellied bustards (Eupodotis senegalensis) suggests monogamous pairing in some bustards, but this has not been reported in Kori bustards. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

The breeding season is different in the two subspecies of Kori bustards. In general, A. k. struthiunculus breeds from December to August and A. k. kori breeds from September to February. Recorded laying dates vary considerably. For example, laying dates were recorded from April to June in Somalia and from March to June in Ethiopia. In southern Africa, laying dates were reported from September to December in Zimbabwe and from November to January in Namibia. Breeding success is heavily dependent upon rainfall and in times of drought breeding is reduced significantly. Sexual maturity is usually reached after 3 years in both sexes. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

  • Breeding interval
    Kori bustards breed, in general, once yearly.
  • Breeding season
    The northern subspecies breed from December to August. The southern subspecies breeds from September to February.
  • Range eggs per season
    1 to 2
  • Average time to hatching
    23 days
  • Range fledging age
    4 to 5 weeks
  • Average time to independence
    1 years
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Average age at sexual or reproductive maturity (male)
    3 years

The nest, a scrape in the ground usually near a clump of grass, holds one to two eggs that are incubated solely by the female for approximately 23 days. Once hatched, the chicks are precocial and cared for by the female, although the male is sometimes present. Fledgling occurs after 4 to 5 weeks, but the chicks remain with the mother until the following year. (Hallager and Boylan, 2004; Harrison, et al., 1997)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • protecting
      • female

Lifespan/Longevity

There is little information about lifespans in the wild, but in captivity Kori bustards have been documented to live as long as 26 years. (Hallager and Boylan, 2004)

  • Range lifespan
    Status: captivity
    26 (high) years

Behavior

Kori bustards are usually found alone or in small groups, but occasionally associate in larger flocks. They prefer not to fly and are commonly seen walking quickly with large strides or hiding from the hot sun under trees. They lack a hind toe and thus are restricted to terrestrial habitats. They have no preen gland, but instead produce powder down and practice dust bathing. Although Kori bustards don’t seem to make regular migrations, they are thought to make small migrations in response to rainfall and food supply. Additionally, adult and juvenile males move after breeding season, whereas females don’t appear to do so. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

Communication and Perception

Kori bustards are generally quiet, but when surprised may make a sort of bark or snoring noise. They have been observed growling when their young are threatened. In courtship displays, males make a low roaring noise and perform visual displays, inflating their throats, erecting their neck feathers and fanning their tails. This display shows off the brilliant white undertail coverts and can be seen up to 1 km away. ("BirdLife International", 2007; Hallager and Boylan, 2004)

Food Habits

Kori bustards are omnivorous with an extremely varied diet including insects, reptiles, small rodents, birds, carrion, seeds, berries and roots. Insects make up a large portion of their diets, especially when they are. They forage on the ground and are drawn to bush fires where they eat insects killed in the blaze. They are known to consume the gum from Acacia trees, either for the gum itself or for the insects inside the gum. Kori bustards drink water in an unusual manner: instead of scooping up water as most birds do, they actually suck up the water. (Hallager and Boylan, 2004; Harrison, et al., 1997)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • carrion
  • insects
  • Plant Foods
  • roots and tubers
  • seeds, grains, and nuts
  • fruit
  • sap or other plant fluids

Predation

Many species prey on Kori bustards including lions, leopards, caracals, jackals, and eagles. Kori bustard chicks are quite vulnerable to predation and exhibit high mortality rates, although they have cryptic plumage. When alarmed, Kori bustards make barking calls and bend forward and spread their tail and wings to appear larger. Adults will growl when their young are threatened by predators. (Hallager and Boylan, 2004; Harrison, et al., 1997)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Kori bustards have a mutualistic association with carmine bee-eaters (Merops nubicus), which often perch on their backs. As a Kori bustard forages they stir up insects that the bee-eaters capture. Kori bustards may get some benefit in return from the bee-eaters, such as help in detecting predators. ("BirdLife International", 2007; Hallager and Boylan, 2004; Harrison, et al., 1997)

Mutualist Species

Economic Importance for Humans: Positive

Kori bustards are interesting birds to watch because of their size, plumage and courtship display patterns. Because of this, they may enhance the tourism industry in the many African countries in which they live. They are also hunted for their meat.

Economic Importance for Humans: Negative

There are no reported negative effects of Kori bustards on humans.

Conservation Status

Despite some decline in Kori bustard populations and habitat fragmentation, they are still common in some areas. Kori bustards are considered a species of least concern according to the IUCN redlist because their decline, although not quantified, appears to be below 30% over the last ten years. Despite their least concern status, multiple threats face this species including habitat destruction from farming, livestock grazing, human encroachment, collisions with power lines, and poaching. Although still common in major game reserves and a few other areas, they are uncommon in many areas where they once thrived and are declining throughout their range. This is of particular concern because of their low fecundity and decreased breeding in dry years. ("BirdLife International", 2007; Hallager and Boylan, 2004)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Jill Bible (author), Stanford University, Terry Root (editor, instructor), Stanford University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

2007. "BirdLife International" (On-line). Accessed May 13, 2007 at http://www.birdlife.org.

Hallager, S., J. Boylan. 2004. "Kori Bustard Species Survival Plan Husbandry Manual" (On-line pdf). Accessed May 13, 2007 at http://www.gruitag.org/uploads/media/kori_bustard_husbandry_manual.pdf.

Harrison, J., D. Allan, L. Underhill, M. Herremans, A. Tree, V. Parker, C. Brown. 1997. The atlas of southern African birds. Vol. 1: Non-passerines. Johannesburg: BirdLife South Africa.

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