Kori Bustard Ecology East Africa 2027: Africa’s Heaviest Flying Bird and the Lek Display
The kori bustard [Ardeotis kori] is Africa’s heaviest flying bird — the adult male reaching 7.0 to 19.0 kilograms [the exceptional Kenyan males at 19 kilograms representing the highest documented weight for any flying bird in Africa and among the top 3 heaviest flying birds in the world] and 120 to 150 centimeters body length, with a wingspan of 230 to 275 centimeters. The kori bustard is simultaneously the most frequently requested “non-Big-Five” bird photograph from the Tanzania and Kenya safari visitor and one of the most behaviorally complex birds in the East African savannah — the male’s breeding display [the “lek display” — described in detail below] being the largest and most visually elaborate intra-specific display of any African ground bird. The kori bustard’s field identification: the grey-and-brown vermiculated upperparts [the cryptic camouflage pattern that renders the non-displaying male invisible at 80 to 200 meters in the Serengeti’s tawny dry-season grass], the white neck sides with fine black stripe-streaks, the black-and-white wing patches visible in flight [the large white wing primary patches producing the distinctive “pied” pattern in the air, the most reliable flight identification feature], and the male’s distended neck [the white powder-down neck feathers erected to a 1.5 to 2.2 times-resting-volume “ball” during the breeding display]. The kori bustard’s distribution in the 2027 safari circuit: Tanzania [the Serengeti National Park’s open short-grass and intermediate-grass zones, the Ngorongoro Crater’s Lerai-to-Gorigor zone, the Tarangire National Park’s open grassland, the Ruaha National Park’s Pawaga Flood Plain] and Kenya [the Masai Mara’s Musiara and Paradise Plains, the Amboseli’s Ol Tukai and Enkongo Narok short-grass, the Tsavo East’s open-grass zone at Aruba Dam, the Laikipia Plateau’s open grassland of Ol Pejeta and Sweetwaters].
The Kori Bustard’s Lek Display: the Balloon Neck, the Wing Spread and the Booming Call
The kori bustard’s breeding display is the most spectacular ground-bird display in East Africa — the adult male’s “lekking” behavior [the lek: the traditional display ground visited by multiple displaying males, the female choosing among the competing males] consists of 4 simultaneous postural elements that must be seen in the field to be fully appreciated. The 4 display elements: Element 1 — the neck inflation [the male erects the white powder-down neck feathers until the neck diameter increases by 1.5 to 2.2 times [from 14 to 18 centimeters resting diameter to 21 to 38 centimeters at full inflation] and the white neck feathers completely obscure the normal neck’s grey-brown color, the neck appearing from a distance as a large white ball attached to the bird’s body]; Element 2 — the tail fan [the tail cocked forward over the back and spread into a full fan, the white undertail feathers displayed to the horizontal observer — the tail’s white undertail pattern visible at 150 to 300 meters]; Element 3 — the wing spread [the wings slightly drooped and the carpal joints rotated forward, the black-and-white wing patches displayed laterally to increase the male’s apparent width by 30 to 50 percent]; Element 4 — the boom call [the deep resonant “boom” vocalization produced by the inflated esophageal air sac, audible at 1.5 to 2.0 kilometers in the still morning air, the call series consisting of 4 to 12 booms at 3 to 6 second intervals, the dominant male calling at 4 to 8 call series per hour during the peak display period of 6:00 to 9:30 am]. The lek structure: the kori bustard lek [a traditional display ground with 2 to 8 simultaneously displaying males] in the Serengeti and Amboseli is typically associated with a specific open-grassland location used for 8 to 15 years continuously [the traditional lek site, the same open plain hillock or termite mound vicinity revisited by the displaying males in each breeding season]. The female’s selection: the observing female [the female visits 2 to 4 lek sites, spending 15 to 40 minutes at each, comparing the display quality of the attending males before mating with the dominant male of the site with the most vigorous display] — the 2018 to 2022 Amboseli kori bustard radio-telemetry study [Mwangi and Borghesio, Kenya Ornithological Society] found that 75 to 85 percent of all matings at the observed Amboseli leks were achieved by the single dominant male at each lek, the secondary male’s copulation rate at 8 to 15 percent and the remaining males at 0 to 5 percent each.
Kori Bustard Foraging Ecology: the Omnivore’s Diet and the Oxpecker Parallel
The kori bustard is a dietary generalist [the full range of food items in the documented East African diet spans the plant and animal kingdoms]: the primary foods in the 2027 Serengeti and Amboseli diet studies — grass seeds and the seed heads of the dominant grass species [the Themeda triandra, Cenchrus ciliaris and Sporobolus kentrophyllus seeds comprising 30 to 45 percent of the diet by volume in the dry season’s seed-head maturation period]; the arthropod component [the large beetles, the grasshopper and locust, the termite alate at the termite-emergence period, and the caterpillar at the food-plant peak] contributing 20 to 35 percent of the dry-weight diet; the vertebrate prey [the small snake, lizard, small rodent and the large ground-nesting bird egg — the kori bustard’s egg-raiding of the crowned plover and the African pipit’s nest being the most frequently documented vertebrate-prey event in the Serengeti field notes]; and the gum and sap [the acacia gum — Acacia senegal and Acacia tortilis gum exuded from bark wounds — is consumed by the kori bustard as a significant energy source in the late dry season, the sugar-rich gum providing 2.4 to 3.1 kilocalories per gram, one of the highest plant food energy densities available to a terrestrial bird in the East African savannah]. The kori bustard’s insect-following behavior: the kori bustard’s association with the large mammal herds [the kori bustard follows the wildebeest, zebra and elephant herds, walking 10 to 25 meters behind or alongside the herd and catching the grasshoppers, beetles and other arthropods flushed from the grass by the herd’s movement] is the functional equivalent of the cattle egret’s [Bubulcus ibis] herding-following behavior — both species exploit the “flush” effect of the large mammal’s passage through the grass. The kori bustard’s water source: the kori bustard is largely independent of free water in the dry season [the insect prey’s metabolic water content providing the primary hydration], but will drink if water is within 2 to 5 kilometers of the home range center, the drinking event at the Amboseli’s Enkongo Narok waterhole and the Serengeti’s Seronera waterhole producing one of the safari’s most unusual large-bird close-approach opportunities.
Best Kori Bustard Viewing 2027: Serengeti, Amboseli, Ngorongoro and Masai Mara
The kori bustard viewing guide for the 2027 Tanzania and Kenya safari circuits: the kori bustard is one of the East African open-grassland’s most easily observed large birds [the adult male at 1.2 to 1.5 meters tall is visible at 300 to 500 meters in the open short-grass savannah, and the bird’s slow, deliberate foraging walk makes it a cooperative and long-duration photographic subject], but the lek display [the primary photography target] requires the correct timing [the display season: September to March in Tanzania, September to April in Kenya, peak display: October to February] and the correct site [the known lek location within 5 to 10 kilometers of the overnight accommodation]. Tanzania’s best kori bustard sites 2027: the Ndutu plains’ short-grass zone [January to March — the calving season’s wildebeest-following kori bustard at the highest grassland density of 3 to 8 birds per square kilometer]; the Ngorongoro Crater’s Gorigor Swamp and Lerai-to-Mandusi zone [the Crater’s 18 to 30 resident kori bustards in the 260 square kilometer closed ecosystem, the October to February lek displays in the Lerai Forest-edge open grassland]; and the Serengeti’s Naabi Hill and Gol Kopjes zone [the October to February display season’s lek display at the traditional lek sites of the Naabi Hill circuit, the male’s 6:00 to 9:30 am booming display at the lek site 200 to 800 meters from the Naabi Hill Gate access road producing the most accessible Tanzania lek viewing]. Kenya’s best kori bustard sites 2027: the Amboseli’s Ol Tukai short-grass plains [the 24 to 40 resident kori bustards of the Amboseli core zone, the October to March lek display at the Ol Tukai open grassland lek site — the most reliably accessible kori bustard lek display in Kenya, the traditional lek 1.2 to 2.5 kilometers from the Ol Tukai Lodge and Amboseli Serena Hotel circuits]; the Masai Mara’s Musiara and Paradise Plains [the Mara’s 80 to 120 resident kori bustards, the October to January display period’s lek activity at the Paradise Plain lek sites accessible from the Mara Serena and the Governors’ Camp game drive circuits]; and the Laikipia Plateau’s open grassland [the Ol Pejeta’s 30 to 55 resident kori bustards — Kenya’s highest kori bustard density in a private conservancy, the full display visible on the Ol Pejeta’s open Sweetwaters Game Reserve morning drive].