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The African jacana

28 January 2015

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The African jacana Actophilornis africanus was originally described scientifically as Parra africana by Gmelin in 1789 based on a specimen from Ethiopia. An adult African jacana is some 23 to 32 cm tall, but the male only weighs around 140 g and the female 230 g although the sexes are alike in plumage colouration. The adults have a black crown and back of the neck while the sides of the face, chin and throat are white. The chest is golden yellow and the mantle, back, rump, tail, wings and belly are rich chestnut in colour but the primary feathers are black. The bill and the fleshy frontal shield are vividly blue, the eyes are brown and the legs and feet are grey. Juveniles can be confused with the lesser jacana Microparra capensis but are larger than it.

As the name indicates the African jacana mainly occurs in the tropical and subtropical regions of Africa but its range extends along rivers into desert areas, such as along the Orange River into the Richtersveld, and it occurs as vagrants in the Namib Desert and the Kalahari. Probably in response to the epemeral nature of its wetland habitat, the African jacana is highly mobile and nomadic, moving several hundred kilometres at times. Its habitat consists of permanent, seasonal and ephemeral shallow, freshwater wetlands and the margins of slow-flowing rivers with low, evergreen vegetation. It is especially attracted to water bodies that have water lilies, willowherbs, pondweeds and hornworts on which to walk while foraging.

African jacanas usually occur in pairs, but they may sometimes form loose flocks. The are conspicuous, noisy waterbirds that are active throughout the day but usually roost at night in groups of from five to 50, but sometimes alone. When walking on floating plants they use a high-stepping gait and sometimes avoid sinking into the water by running, although they also swim readily. Where hippopotamuses occur they will perch on their backs when they are partially submerged. They will dive into the water and swim underwater to avoid detection when they are moulting from January to April or September to November. When flying, the legs trail behind at an angle of 45 degrees.

Foraging is done throughout the day by walking across floating plants and pecking at prey or sometimes by pulling up and turning over submerged plant stems. They mostly eat water insects and their larvae, but they also eat flies, dragonflies, beetles, spiders, bees, small fishes, crustaceans and snails. When large mammals wade in water the African jacana will forage on the insects that are being disturbed by them. In the Central African Republic it is known to peck flesh from open wounds on hippopotamuses.

A female will mate with different males during the summer months, but after laying the eggs she is not involved further. African jacanas are solitary nesters with adjacent nests being more than 50 m apart. The males are territorial and fight to secure a territory, and they mate by hopping up and down while calling to a female from a rudimentary platform of plant stems. Copulation is brief and only lasts some 35 to 63 seconds. The nest is a flimsy, sodden platform in cover and it is made from the stems of aquatic plants that are pulled into a heap in still water. The nest is mainly built by the male and several platforms may have to be built before one is selected for laying the eggs which are some 20 mm above the water surface although wet material may be added throughout incubation. When the water level changes rapidly, a nest may become exposed on a mud flat, or a nest may be flooded causing them to be moved to another platform up to 30 m away. This is done either by rolling the eggs with the bill or by pushing a floating egg when swimming.

Four pear-shaped, thick-shelled, smooth, highly glossy, tan eggs with thick, wavy, scroll-like black and dark brown lines or markings are laid on consecutive days. The colouration of the eggs varies between females but a specific female will lay eggs with the same colour throughout her lifetime. Up to ten clutches may be laid in one season with intervals ranging from four to 28 days between successive clutches. Incubation starts after laying the third egg and lasts for 23 to 27 days but only the male incubates the eggs, usually only in the morning and evening when the ambient temperature is high. The thick egg shells prevent them from cooling rapidly but the male may shield the eggs with his wings when it is hot. The male often leaves the eggs to allow him to forage. When incubating he is aggressive to other waterbirds.

The eggs hatch in the laying order and the male is excitable at hatching. The hatchlings are covered in down and have a reddish crown, a black stripe down the middle of the back and black lines from behind the eye to the nape of the neck. The back and rump are mostly reddish with a buffy white line on either side of the centre that is edged with thinner black lines. The underparts are white and the legs and feet are greenish grey. The nestlings are cared for entirely by the male who may carry three to four small nestlings under the wings. The nestlings are attended closely by the male for the first 14 days but parental care stops when they are 40 to 50 days old. The nestlings start to fly when they are 39 to 44, but sometimes up to 75, days old. Breeding success varies and the eggs are especially vulnerable to predators such as water monitors, the purple swamp hen and otters. The juveniles attain an adult plumage when they are nine to 12 months old.

 

Reference:

Hockey, P A R, W R J Dean and P G Ryan (eds) 2005. Roberts – birds of southern Africa, seventh edition. Cape Town: The John Voelcker Bird Book Fund, pp 382 - 383.

 

article by Prof J du P Bothma

 

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