Thursday, 16 May 2013

Species Spotlight - Kori Bustard


Kori Bustard in the middle of a mating call.
The Kori Bustard is cryptically colored, being mostly grey and brown in color, finely patterned with black and white coloring. 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. 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 thick neck. The belly is white and the tail has broad bands of brownish-gray and white coloration. The head is large and the yellow legs are relatively long. Females are similar in plumage but are much smaller, often weighing 2-3 times less than the male. The juvenile is similar in appearance to the female, but are browner with more spotting on the mantle.

The male Kori Bustard is 120 to 150 cm (3.9 to 4.9 ft), stands 71–120 cm (2.33–3.9 ft) tall and have a wingspan about 230 to 275 cm (7.5 to 9.02 ft). On average, male birds weigh between 10.9–16 kg (24–35 lb), averaging 13.5 kg (30 lb) but exceptional birds may weigh up to 20 kg (44 lb). Reports of outsized specimens weighing 23 kg (51 lb), 34 kg (75 lb) and even 40 kg (88 lb) 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 achieve similarly high weights, making the male Kori and Great not only the two largest bustards, but also arguably the heaviest living flying animals. The female Kori Bustard weighs an average of 4.8 to 6.1 kg (11 to 13 lb), with a range of 4.3 to 6.6 kg (9.5 to 15 lb). Female length is from 80 to 120 cm (2.6 to 3.9 ft) and they usually stand less than 60 cm (2.0 ft) tall and have a wingspan of less than 220 cm (7.2 ft). The wing chord can measure from 58.5 to 83 cm (23.0 to 33 in), the tail measures from 30–45 cm (12–18 in), the culmen from 7 to 12.5 cm (2.8 to 4.9 in) and the tarsus from 16 to 24.5 cm (6.3 to 9.6 in). Body size is generally greater in the populations of southern Africa and body mass can vary based upon rain conditions.

Behavior

Kori Bustards spend most of their time on the ground, though can forage occasionally in low bushes and trees. Being a large and heavy bird, it avoids flying if possible. 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. This large bird has a loud, booming mating call which is often uttered just before dawn and can be heard from far away. Locally, they are regularly found with bee-eaters 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 male's mating call a deep, resonant woum-woum-woum-woum (Ginn et al. 1989) or oom-oom-oom (Sinclair & Ryan 2003) or wum, wum, wum, wum, wummm . This call ends with the bill snapping which is only audible at close range. They also utter a ca-caa-ca, repeated several times for up to 10 minutes. This call carries long distances. Outside of the breeding display, Kori Bustards are often silent. A high alarm call, generally uttered by females, is sometimes heard. They utter a deep vum on takeoff.

Information from Wikipedia