Overview

Distribution

Range Description

This species has an extremely large but disjunct range in sub-Saharan Africa. occurring from Ethiopia and Somalia south to Tanzania, and from southern Angola and Zimbabwe south to South Africa. Declines in its overall range over the past century appear to have been relatively modest, but it has apparently undergone considerable population declines in all range states except Zambia (few records) and Angola (Senyatso et al. 2012).
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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.

Biogeographic Regions: ethiopian (Native )

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Eastern and Southern Africa: S Ethiopia, NW Somalia - N Tanzania; S Angola, Namibia - S Mozambique, South Africa (not SW or E)

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Physical Description

Morphology

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.

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.

Range mass: 5.5 to 19 kg.

Range length: 105 to 128 cm.

Range wingspan: 60 to 76 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
It occurs in flat, arid, mostly open country such as grassland, karoo, bushveld, thornveld, scrubland and savanna but also including modified habitats such as wheat fields and firebreaks (del Hoyo et al. 1996). In Kenya at least, birds may move into woodland in the dry season. The diet includes a wide range of plants and animals including insects, reptiles, small rodents, birds, carrion, seeds, berries and roots (del Hoyo et al. 1996). It is largely sedentary, but does undertake local movements.

Systems
  • Terrestrial
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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.

Range elevation: 700 to 2000 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland

  • 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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Flat open country

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Dispersal

Movements and dispersal

Resident

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Trophic Strategy

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.

Animal Foods: birds; mammals; reptiles; carrion ; insects

Plant Foods: roots and tubers; seeds, grains, and nuts; fruit; sap or other plant fluids

Primary Diet: omnivore

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Associations

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.

Mutualist Species:

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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.

Known Predators:

Anti-predator Adaptations: cryptic

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Life History and Behavior

Behavior

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.

Communication Channels: visual ; acoustic

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Life Expectancy

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.

Range lifespan

Status: captivity:
26 (high) years.

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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.

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.

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.

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.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

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.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Protecting: Female)

  • 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.
  • 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.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Ardeotis kori

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2013

Assessor/s
BirdLife International

Reviewer/s
Butchart, S.

Contributor/s
Coetzee, R., Shaw, J. & Cordeiro, N.

Justification
This huge African bustard is suspected to be undergoing moderately rapid population declines across much of its range owing to a variety of threats including collisions with power lines, hunting and habitat degradation. It has consequently been uplisted to Near Threatened.

History
  • 2012
    Least Concern
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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.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: least concern

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Population

Population
The global population size has not been quantified, but the species is reported to be still common where undisturbed (del Hoyo et al. 1996). The population in South Africa has been estimated at 2,000-5,000 birds (Barnes 2000).

Population Trend
Decreasing
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Threats

Major Threats

Collisions with high voltage power lines are a major threat in the Karoo of South Africa and in Namibia, and presumably elsewhere where there are power lines within the range (J. Shaw and R. Coetzee in litt. 2013). Declines in Tanzania can probably be attributed to trade in the species during the 1990s and 2000s (N. Cordeiro in litt. 2013). There is also anecdotal information from South Africa indicating that the species is used in the muti (traditional medicine) trade, hunted for bush meat, and illegally kept as pets (R. Coetzee in litt. 2013). The causes of population declines and range losses in many parts of the distribution are unknown, but have been hypothesised to include persecution, rangeland degradation and shrub encroachment (Senyatso et al. 2012). In Botswana, unregulated hunting appears to be a genuine threat while cattle-induced bush encroachment is not (Senyatso 2011).

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Management

Conservation Actions

Conservation Actions
Conservation and research actions underway
CITES Appendix II. The species is legally protected in many range states.

Conservation and research actions proposed
Continue to raise awareness to stop hunting for bushmeat and traditional medicine, and to encourage the public to report mortality from power lines. All new infrastructure (power lines, wind turbines) should be sited and mitigated appropriately, and dangerous sections of line should be retrofitted with appropriate mitigation. Carry out further research into mitigation measures for power line collisions.
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

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

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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.

Positive Impacts: food ; ecotourism

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Wikipedia

Kori bustard

The Kori Bustard (Ardeotis kori) is a large bird native to Africa. It is a member of the bustard family, which all belong to the order Gruiformes and are restricted in distribution to the Old World. It is one of the four species (ranging from Africa to India to Australia) in the large-bodied Ardeotis genus. In fact, the male Kori Bustard may be the heaviest living animal capable of flight. This species, like most bustards, is a ground-dwelling bird and an opportunistic omnivore. Male Kori Bustards, which can be more than twice as heavy than the female, attempt to breed with as many females as possible and then take no part in the raising of the young. The nest is a shallow hallow into the earth, often disguised by nearby obstructive objects such as trees. The specific epithet kori is derived from the Tswana name for this bird - Kgori.[2]

Distribution[edit]

A. k. struthiunculus in Amboseli, Kenya

The Kori Bustard is found throughout southern Africa, except in densely wooded areas. They are common in Botswana and Namibia, extending into southern Angola and marginally into southwestern Zambia. In Zimbabwe they are generally sparse but locally common, particularly on the central plateau. Their distribution range extends along the Limpopo River valley into southern Mozambique and the eastern lowveld of South Africa. In South Africa they are also infrequent to rare in the Free State, North West and Northern Cape Provinces, extending southwards into the interior of the Western and Eastern Cape Provinces. Kori Bustards are absent from the coastal lowlands along the south and east of South Africa and from high mountainous areas. This species is common in Tanzania at Ngorongoro National Park, Kitulo National Park and Serengeti National Park. A geographically disjunct population also occurs in the deserts and savanna of northeastern Africa. Here, the species ranges from extreme south Sudan, north Somalia, Ethiopia through all of Kenya (except coastal regions), Tanzania and Uganda.[3] Kenya may hold the largest population of Kori Bustards of any country and it can even border on abundant in the North Eastern Province.[4] They are usually residential in their range, with some random, nomadic movement following rainfall.[4]

Habitat[edit]

This species occurs in open grassy areas, often characterized by sandy soil, especially Kalahari sands, and short grass usually near the cover of isolated clumps of trees or bushes.[4] It may be found in plains, arid plateaus, highveld grassland, arid scrub, lightly wooded savanna, open dry bushveld and semi-desert.[5] Where this species occurs, annual rainfall is quite low, at between 100 and 600 mm (3.9 and 23.6 in).[5] Breeding habitat is savanna in areas with sparse grass cover and scattered trees and shrubs. When nesting they sometimes use hilly areas.[6] They follow fires or herds of foraging ungulates, in order to pick their various foods out of the short grasses. They may also be found in cultivated areas, especially wheat fields with a few scattered trees.[4] This bustard is not found in well-wooded and forested areas due to the fact that it needs a lot of open space in which to take off.[4] In arid grassland areas it is found along dry watercourses where patches of trees offer shade during the heat of the day.[7]

Description[edit]

The Kori Bustard is cryptically coloured, being mostly grey and brown, finely patterned with black and white coloring. The upper parts and neck are a vermiculated black and greyish-buff colour.[2] 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.[8] A black collar at the base of the hind-neck extends onto the sides of the breast.[9] The feathers around the neck are loose, giving the appearance of a thicker neck then they really have.[10] The belly is white and the tail has broad bands of brownish-gray and white coloration.[2] Their feathers contain light sensitive porphyrins, which gives their feathers a pinkish tinge at the base- especially noticeable when the feathers are shed suddenly.[7] The head is large and the legs are relatively long. The eye is pale yellow, while the bill is light greenish horn coloured, relatively long, straight and rather flattened at the base. The legs are yellowish. The feet have three forward facing toes.[8] 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 visibly is thinner legged and slimmer necked.[8] The juvenile is similar in appearance to the female, but are browner with more spotting on the mantle, with shorter crest and neck plumes.[5] Male juveniles are larger than females and can be the same overall size as the adult male but tends to be less bulky with a thinner neck, shorter head crest, paler eyes and a darker mantle.[7]

A close-up of the plumage of a captive male

Two subspecies are current recognized:

Size[edit]

The male Kori Bustard is 120 to 150 cm (3 ft 11 in to 4 ft 11 in), stands 71–120 cm (2 ft 4 in–3 ft 11 in) tall and have a wingspan about 230 to 275 cm (7 ft 7 in to 9 ft 0 in). Male birds may typically weigh between 7 and 18 kg (15 and 40 lb), averaging 13.5 kg (30 lb), but exceptional birds may weigh up to at least 20 kg (44 lb).[13] Males weighing 16 to 19 kg (35 to 42 lb) or more are typical only in A. k. struthiunculus.[7][14] Reports of outsized specimens weighing 23 kg (51 lb),[8] 34 kg (75 lb)[15] and even "almost" 40 kg (88 lb)[16] have been reported, but none of these giant sizes have been verified and some may be from unreliable sources. Among bustards, only male Great Bustards (Otis tarda) achieve similarly high weights, making the male Kori and Great not only the two largest bustards but also arguably the heaviest living flying animals. As a whole, other species, such as Dalmatian Pelican (Pelecanus crispus), Andean Condor (Vultur gryphus) and Trumpeter Swan (Cygnus buccinator), might weigh more on average between the sexes but are less sexually dimorphic in mass than the giant bustards.[14][15] The female Kori Bustard weighs an average of 4.8 to 6.1 kg (11 to 13 lb), with a range of 3 to 7 kg (6.6 to 15.4 lb). Female length is from 80 to 120 cm (2 ft 7 in to 3 ft 11 in) and they usually stand less than 60 cm (2 ft 0 in) tall and have a wingspan of less than 220 cm (7 ft 3 in). The standard measurements of the male include a wing chord of 69.5 to 83 cm (27.4 to 32.7 in), a tail measures from 35.8–44.7 cm (14.1–17.6 in), a culmen from 9.5 to 12.4 cm (3.7 to 4.9 in) and a tarsus from 20 to 24.7 cm (7.9 to 9.7 in). Meanwhile, the female's standard measurements are a wing chord of 58.5 to 66.5 cm (23.0 to 26.2 in), a tail of 30.7 to 39.5 cm (12.1 to 15.6 in), a culmen from 7 to 10.4 cm (2.8 to 4.1 in) and a tarsus from 16 to 19.5 cm (6.3 to 7.7 in).[11][13][14][15][17] Body mass can vary considerably based upon rain conditions.[18]

Confusion species[edit]

The size and dark crest are generally diagnostic amongst the bustards found in the Kori Bustard's range.[19] However, East Africa holds the greatest diversity of bustards anywhere, including even some other quite large species, and these have the potential to cause confusion. Kori Bustards are distinguished from Denham's Bustard (Neotis denhamii) and Ludwig's Bustard (Neotis luwigii), both of which they sometimes forage with, by their greyer appearance and by their lack of a tawny red hind-neck and upper mantle. In flight it can be distinguished from both of these somewhat smaller bustards by not displaying any white markings on the upperwing, which is uniformly grey here. Both Stanley's and Ludwig's bustards lack the Kori's dark crest.[2][4][19] More similar to, and nearly the same size as, the Kori is the closely related Arabian Bustard (Ardeotis arabs) (despite its name, the latter species ranges well into East Africa). However, the Arabian species has white-tipped wing coverts, a browner back and very fine neck vermiculations and also lacks the black base to the neck and the black in the wing coverts as seen in the Kori.[2][3]

Behaviour[edit]

Male A. k. struthiunculus at Maasai Mara, Kenya

Kori Bustards spend most of their time on the ground, with up to 70% of their time being on foot.[2] Although, they can forage occasionally in low bushes and trees. There is a lone report of a bird sighted in Kenya perched at the top of a tree.[20] This bustard is a watchful and wary bird. Their behavior varies however, and they are usually very shy, running or crouching at the first sign of danger; at other times they can be completely fearless of humans.[2] They have a hesitant, slow manner of walking, and when they detect an intruder they try to escape detection by moving off quietly with the head held at an unusual angle of between 45° and 60°.[4] Being a large and heavy bird, it avoids flying if possible. When alarmed it will first run and, if pushed further, will take to the air on the run with much effort, its wings making heavy wingbeats. Once airborne it flies more easily with slow, measured wingbeats, with the neck extended and the legs folded. It usually remains low and lands again within sight.[18] When they land, Kori Bustards keep their wings spread and only fold them when the bird has slowed down to a walking speed.[4] Kori Bustards have no preen gland, so to keep clean, they produce a powder down. Sun bathing and dust bathing are practiced.[7] This bird has a loud, booming mating call which is often uttered just before dawn and can be heard from far away. Mostly residential, Kori Bustards may engage in nomadic movements.[19] These migratory movements are probably influenced by rainfall and there is no evidence suggesting any regular pattern. These local migrations take place at night but have not been mapped. In the Etosha National Park these birds have been recorded moving up to 85 km (53 mi) from mopane woodland to open grassland plains and returning again the following season.[4] Trial satellite tagging of one male Kori Bustard by the National Museums of Kenya demonstrated a migration along the Rift Valley between Tanzania and southern Sudan.[21] Additionally, adult and juvenile males move after breeding season, whereas females don’t appear to do so.[22] Generally the Kori Bustard feeds during the morning and in the evening, spending the rest of the day standing still in any available shade.[4]

Voice[edit]

Less vocal than other bustards, the Kori Bustard generally 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 agnostic encounters.[2] Chicks as young as two weeks will also emit this alarm call when startled.[7] The male's mating call is a deep, resonant woum-woum-woum-woum[4] or oom-oom-oom[3] or wum, wum, wum, wum, wummm.[8] This call ends with the bill snapping which is only audible at close range.[4] Outside of the breeding display, Kori Bustards are often silent. A high alarm call, generally uttered by females, is sometimes heard. They may utter a deep vum on takeoff.[5]

Sociality[edit]

During the mating season, these birds are usually solitary but for the breeding pair. Otherwise, they are somewhat gregarious, being found in groups often including 5 to 6 birds but occasionally groups can number up to 40 individuals. Larger groups may be found around an abundant food source or at watering holes. In groups, birds are often fairly far apart from each other, often around a distance of 100 m (330 ft). Interestingly, foraging groups are often single-sex. Such groups do not last long and often separate after a few days. These groups are believed advantageous both in that they may insure safety in numbers against predation and may bring the bustards to prime food sources.[3]

Feeding[edit]

Female of the nominate race near Etosha National Park, Namibia.

Walking slowly and sedately, they forage by picking at the ground with the bills and are most active in the first and last hours of daylight. Kori Bustards are quite omnivorous birds. Insects are an important food source, with common species such as locusts, grasshoppers, dung beetles (Scarabaeus ssp.) and caterpillars being most often taken. They may follow large ungulates directly to catch insects flushed by them or to pick through their dung for edible invertebrates. During outbreaks of locusts and caterpillars, Kori Bustards are sometimes found feeding on them in numbers. Other insect prey can include bush-crickets (Tettigonia ssp.), termites, hymenopterans and solifuges. Scorpions and molluscs may be taken opportunistically as well.[4]

Small vertebrates may also been taken regularly, including lizards, chameleons, small snakes, small mammals (especially rodents) and bird eggs and nestlings. They may occasionally eat carrion, especially from large animals killed in veld fires. Plant material is also an important food. Grasses and their seeds are perhaps most prominent plant foods, but they may also eat seeds, berries, roots, bulbs, flowers, wild melons and green leaves. This bustard is very partial to Acacia gum. This liking has given rise to the Afrikaans common name Gompou or, literally translated, "gum peacock".[4] They drink regularly when they can access water but they can found as far as 40 km (25 mi) from water sources.[4] Unusually, they suck up rather than scoop up water.[22]

Breeding[edit]

Male Kori bustard (A. k. struthiunculus) displaying in Ngorongoro Conservation Area.

Kori Bustards' breeding season is different between the two subspecies. In general, A. k. struthiunculus breeds from December to August and A. k. kori breeds from September to February.[22] Breeding is closely tied with rainfall, and in drought years, may be greatly reduced or not even occur.[23] Kori Bustards engage in lek mating. All bustards have polygynous breeding habits, in which one male displays to attract several females, and mates with them all.[24] Males display at regularly used sites, each male utilizing several dispersed leks or display areas. These displays usually take place in the mornings and evenings. The courtship displays of the males are impressive and elaborate, successfully advertising their presence to potential mates.[6] The males hold their heads backwards, 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 visible up to 1 km (0.62 mi) away during display.[24] Their wings are drooped and their tails are raised upwards and forwards onto their backs like a turkey, the retrices being held vertically and their undertail coverts fluffed out. They enhance their performance with an exaggerated bouncing gait. When displaying they stride about with their necks puffed out, their tail fanned and their wings planed and pointed downward.[25] 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.[26] Occasionally fights between males can be serious during the mating season when display areas are being contested, with the two competitors smashing into each other's bodies and stabbing each other with their bills. They may stand chest-to-chest, tails erect, bills locked and 'push' one another for up to 30 minutes.[5] Following the display, the copulation begins with the female lying down next to the dominant displaying male. He stands over her for 5–10 minutes, stepping from side to side and pecking her head in a slow, deliberate fashion, tail and crest feathers raised. She recoils at each peck. He then lowers himself onto his tarsi and continues pecking her until he shuffles forward and mounts with wings spread. Copulation lasts seconds after which both stand apart and ruffle their plumage. The female then sometimes barks and the male continues with his display.[6][7]

As with all bustards, the female makes no real nest. The female Kori Bustard lays her eggs on the ground in a shallow, unlined hollow, rather than the typical scrape. This nest is usually located within 4 m (13 ft) of a tree or shrub, termite mound or an outcrop of rocks. The hollow may measure 300–450 mm (12–18 in) in diameter and be almost completely covered by the female when she's incubating.[6] Due to their ground location, nests are often cryptic and difficult for a human to find, unless stumbled onto by chance.[6] The same site is sometimes reused in successive years. The Kori Bustard is a solitary nester and there is no evidence of territoriality amongst the females.[6] Usually two eggs are laid, though seldom 1 or 3 may be laid. Clutch size is likely correlated to food supply.[6][23] They are cryptically colored with the ground color being dark buff, brown or olive and well marked and blotched with shades of brown, grey and pale purple. Eggs are somewhat glossy or waxy and have a pitted-looking surface. Egg size is 81 to 86 mm (3.2 to 3.4 in) in height and 58 to 61 mm (2.3 to 2.4 in) width. The eggs weigh individually about 149 g (5.3 oz), with a range of 121 to 178 g (4.3 to 6.3 oz).[4][6][24]

The female, who does all brooding behavior alone without male help, stays at the nest 98% of the time, rarely eating and never drinking.[25] Occasionally she stretches her legs and raises her wings overhead. The female regularly turns the eggs with her bill. The female's plumage is drab and earth-colored, which makes her well camouflaged. She occasionally picks up pieces of vegetation and drops them on her back to render her camouflage more effective.[6] If they need to feed briefly, the females go to and from the nest with a swift, silent crouching walk.[25] If approached the incubating bird either slips unobtrusively from the nest or sits tight, only flying off at the last moment.[6] The incubation period is 23 to 30 days, though is not known to exceed 25 days in wild specimens.[25] The young are precocial and very well camouflaged. The lores are tawny, the crown tawny mottled black. A broad white supercilium bordered with black meets on the nape, extending down the centre of the nape. The neck is white with irregular black stripes from behind the eye and from the base of the lower mandibles. The upper parts are tawny and black with 3 black lines running along the back. The underparts are whitish.[6] When the chicks hatch, the mother brings them a steady stream of food, most of it soft so the chicks can eat it easily.[27] Captive hatchlings weigh 78 to 116 g (2.8 to 4.1 oz) on their first day but grow quickly.[24] The precocial chicks are able to follow their mother around several hours after hatching.[7] After a few weeks, the young actively forage closely with their mothers. They fledge at 4 to 5 weeks old, but are not self-assured fliers until 3 to 4 months.[5] On average, around 67% of eggs successfully hatch (testimony to the effective camouflage of nests) and around one of the two young survive to adulthood. In Namibia and Tanzania, breeding success has been found to be greatly reduced during times of drought.[23] Most young leave their mothers in their second year of life, but do not start breeding until they are fully mature at three to four years old in both sexes in studies conducted both of wild and captive bustards.[5][7] The lifespan of wild Kori Bustards is not known but they may live to at least 26 or possibly 28 years old in captivity.[7][24]

Interspecies interactions[edit]

Ardeotis kori kori flying near Windhoek, Namibia.

The Kori Bustard is often found in areas with a large quantity of antelope and other game. In Tanzania, Kori Bustards regularly attend Blue Wildebeest (Connochaetes taurinus) herds and feed on the small mammals disturbed by them.[28] Sometimes Kori Bustards are found with Southern Carmine Bee-eaters (Merops nubicoides) and Northern Carmine Bee-eaters (Merops nubicus) riding on their backs as they stride through the grass. The bee-eaters make the most of their walking perch by hawking insects from the bustard's back that are disturbed by the bustard's wandering. This is regularly seen in Chobe National Park, Botswana but has only been reported once elsewhere. There is also one record of Fork-tailed Drongos (Dicrurus adsimilis) perching on their backs in a similar manner.[4] Kori Bustards have been observed to behave aggressively to non-threatening animals at watering holes, as they may raise their crests, open their wings and peck aggressively. They have been seen acting aggressively towards Red-crested Korhaans (Eupodotis ruficrista), Springbok (Antidorcas marsupialis), Plains zebra (Equus burchelli) and Gemsbok (Oryx gazella).[4] When kept in captivity, Kori Bustards have been kept together with numerous other (typically African) species in close quarters. Fifteen other bird species and 12 mammals have successful co-habitated with them (even rhinoceros). However, the bustards sometimes injure or kill the young of everything from waterfowl to dik-diks and may be killed by larger species from ostriches (Struthio camelus) to zebras (Equus ssp.).[24]

Being a large, ground-dwelling bird species, the Kori Bustard is vulnerable to many of Africa's myriad of formidable terrestrial predators. Leopards (Panthera pardus), caracals (Caracal caracal), cheetahs (Acinonyx jubatus), lions (Panthera leo), spotted hyena (Crocuta crocuta), African rock pythons (Python sebae), jackals (Canis ssp.), Verreaux's eagle (Aquila verreauxii) and martial eagles (Polemaetus bellicosus) are amongst their potential natural predators. Additionally, warthogs (Phacochoerus africanus), tawny eagles (Aquila rapax), mongooses and baboons (Papio ssp.) may eat eggs and small chicks.[4][7][24] When alarmed, Kori Bustards make barking calls and bend forward and spread their tail and wings to appear larger.[7] Adults will growl when their young are threatened by predators.[22] Chicks tend to be the most vulnerable to predators by far. Many, despite their cryptic camouflage and the mother's defenses, are regularly picked off by jackals and leopards at night.[4] Up to 82% of Kori Bustard chicks die in their first year of life.[23] When found with carmine bee-eaters, the smaller birds may incidentally provide some protection from predators due to their vigilance.[29] The display of the adult male may make it more conspicuous to larger predators, such as hyenas or lions.[6] A shock display may be performed when a bird is alarmed. While too large to be prey for most predatory birds, it is known that the Martial Eagle is a serious natural enemy even for adult bustards. In one documented attack by a Martial Eagle on an adult Kori Bustard, both birds ended up wounded, the eagle with a bleeding leg from the bustard's counterattack, but the bustard more seriously injured, with a broken wing and several open wounds. Although it walked away, the injured bustard in the confrontation was found dead the next morning, being fed on by a jackal.[30]

Status[edit]

Richard Meinertzhagen holds a shot Kori Bustard near Nairobi in 1915, illustrating the bird's huge size.

The Kori Bustard is generally a somewhat scarce bird. listed on Appendix II of CITES, and the 2000 Eskom Red Data Book for Birds lists the status of the nominate race as Vulnerable, estimating that in the next three generations, it is expected to decline by 10% in South Africa.[5][31] In protected areas, they can be locally common.[3] Viable populations exist in unprotected areas as well (e.g. Ethiopia and Sudan, and in Tanzania around Lake Natron and in the foothills of Mount Kilimanjaro) but in these areas, the birds are hunted.[7] They have been much reduced by hunting, having been traditionally snared in Acacia gum baits and traps. Although no longer classified as game birds, they are still sometimes eaten.[8] In Namibia, they indicated as game as they are called the “Christmas turkey” and in South Africa, the “Kalahari Kentucky".[7][23] Hunting of bustards is difficult to manage. The Kori Bustard is now generally uncommon outside major protected areas. Habitat destruction is a major problem for the species, compounded by bush encroachment due to overgrazing by livestock and agricultural development.[32] Poisons used to control locusts may also effect and collisions with overhead power wires regularly claim Kori Bustards.[3] One 10 km (6.2 mi) stretch of overhead powerlines in the Karoo killed 22 Kori Bustards during a five-month period.[7] Kori Bustards tend to avoid areas used heavily by humans.[33] Nonetheless, because it has such a large range and its rate of decline is thought to be relatively slow, the kori bustard is not currently listed in a threatened category on the IUCN Red List. This species is prominent in many native African cultures various due to its imposing, impressive size, spectacular displays by adult males and cryptic nature of the nesting female. The Kori Bustard features in dances and songs of the San people of Botswana. Paintings of these bustards feature in ancient San rock art.[3]

References[edit]

  1. ^ BirdLife International (2013). "Ardeotis kori". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ a b c d e f g h Williams, J.G. 1995. Collins Field Guide: Birds of East Africa. HarperCollins, Hong Kong.
  3. ^ a b c d e f g h Sinclair I. & Ryan P. 2003. A comprehensive illustrated field guide : Birds of Africa south of the Sahara. Struik Publishers, Cape Town.
  4. ^ a b c d e f g h i j k l m n o p q r s t Ginn P.J., McIlleron W.G. & Milstein P. le S. 1989. The Complete Book of southern African birds. Struik Winchester, Cape Town.
  5. ^ a b c d e f g h Maclean, G.L. 1993. Robert's Birds of Southern Africa. Sixth Edition. John Voelcker Bird Book Fund, Cape Town.
  6. ^ a b c d e f g h i j k l Tarboton W. 2001. A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers (Pty) Ltd, Cape Town.
  7. ^ a b c d e f g h i j k l m n o Sara Hallager. "Smithsonian Conservation Biology Institute- Kori Bustard". The Smithsonian Institute. Retrieved 2013-08-30. 
  8. ^ a b c d e f Newman, K. 1992. Newman's Birds of Southern Africa : Expanded Edition, Fourth Edition. Southern Book Publishers (Pty) Ltd, Halfway House.
  9. ^ Alden, P.C., Estes, R.D., Schlitter, D. and McBride, B. (1996) Collins Guide to African Wildlife. HarperCollins Publishers, London.
  10. ^ Newman, K. (ed) 1971. Birdlife in southern Africa. Macmillan, Johannesburg, South Africa.
  11. ^ a b Johnsgard, Paul A. 1990. Bustards: Stalkers of the Dry Plains. Zoonooz 63(7): 4-11.
  12. ^ del Hoyo, J; Elliot, A; Sargatal, J (1996). Handbook of the Birds of the World 3. Barcelona: Lynx Edicions. ISBN 84-87334-20-2. 
  13. ^ a b "Kori Bustard Research". National Zoo, FONZ: Washington D.C. Retrieved 2013-07-26. 
  14. ^ a b c CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.
  15. ^ a b c Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9. 
  16. ^ Main, M. 1987. Kalahari: Life's Variety in Dune and Delta. Southern Book Publishers (Pty) Limited, Johannesburg.
  17. ^ Bustard profile (2011).
  18. ^ a b Liversidge, R. 1991. The Birds Around Us - Birds of the Southern African Region. Fontein Publishing Company (Pty) Ltd, Parklands.
  19. ^ a b c Sinclair I., Hockey P. & Tarboton W. 1997. Sasol Birds of Southern Africa. Struik Publishers (Pty) Ltd, Cape Town.
  20. ^ L. Hudson, pers. comm
  21. ^ Njoroge, P. and Launay, F.. 1998. Satellite Tracking of Kori bustards Ardeotis kori in Kenya. Scopus 20: 19-22.
  22. ^ a b c d 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.
  23. ^ a b c d e Osborne, T. and Osborne, L.. Ecology of the Kori bustard in Namibia. Annual Report of the Ministry of Environment and Tourism Permit Office, Namibia. Feb. 1998.
  24. ^ a b c d e f g Hallager, S., J. Boylan. 2004. Kori Bustard Species Survival Plan Husbandry Manual
  25. ^ a b c d Steyn, P. 1996. Nesting Birds : The breeding habits of southern African birds. Fernwood Press, Vlaeberg.
  26. ^ Dennis N., Knight M., Joyce P. 1997. The Kalahari: Survival in a Thirstland Wilderness. Struik Publishers (Pty) Ltd, Cape Town.
  27. ^ Lichtenberg, Elinor M.; Hallager, Sara (2007). "A Description of Commonly Observed Behaviors for the Kori Bustard (Ardeotis Kori)". Journal of Ethology 26 (1): 17–34. doi:10.1007/s10164-006-0030-z. hdl:10088/6028. 
  28. ^ Dean W.R.J. & MacDonald, I.A.W. 1991. A review of African birds feeding in association with mammals. Ostrich 52:135-155.
  29. ^ Jackson, T.H.E.. 1945. Some Merops-Ardeotis Perching Associations in Northern Kenya. Ibis 87: 284-286.
  30. ^ "Martial Eagle Attack a Kori Bustard in South Africa". BirdForum. Retrieved 2013-07-26. 
  31. ^ Barnes, K.N. (ed.) 2000. The Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland. Birdlife South Africa.
  32. ^ Ottichilo, W., De Leeuw, J., Skidmore, A., Prins, H., and Said, M. 2000. Population trends of large non-migratory wild herbivores and livestock in the Masai Mara ecosystem, Kenya, between 1977 and 1997. African Journal of Ecology 38: 202-216.
  33. ^ Lichtenberg, E.M. and Hallager, S. (2008) A description of commonly observed behaviors for the kori bustard (Ardeotis kori). Journal of Ethology, 26: 17 - 34.
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