Photo: © Shutterstock.com/Utopia_88. African openbills foraging in Kruger National Park, South Africa
THERE are 19 different species of stork in the family Ciconiidae, with the centre of distribution being the tropical regions of the world. The African openbill, like its Asian cousin, has adapted to a diet of snails and freshwater mussels.
The distinctive bill develops as the bird matures, with the mandibles touching only at the tips, so the bill looks as though it should be used like a set of nutcrackers. In practice, the stork holds the snail with its upper mandible, and the tip of the lower mandible is inserted into the shell and is then used to cut the muscle that holds the snail in place. The snail is extracted whole. The upper bill has plate-like structures known as lamellae, which fringe the inner surface and give the bird its specific scientific name, Anastomus lamelligerus. The common name of “clatterbill” refers to the clattering noise they make with the bill during courtship displays. (Other species such as the white stork do this, too.)
The African openbill is a medium-sized stork reaching a height of about 60cm (24in). Its plumage is dark with iridescent colours shot through, like that of a starling. The legs are black and there is a small area of blueish flesh around the eye. The sexes are similar although males are slightly larger than females.
This species is distributed across a large area of Africa, south of the Sahara and including the west side of Madagascar. African openbills are still common throughout their range, although numbers are thought to be declining, particularly in Madagascar where colonies are disturbed by villagers. Threats include habitat loss, pollution and hunting. Specimens are also traded at traditional medicine markets in Nigeria.
The preferred habitat is shallow wetlands where there will be a plentiful supply of the molluscs that it feeds on, probing with its bill in the muddy waters. They have been observed to forage by walking on the backs of hippopotami.
Migration is usually triggered by the rains. Birds migrate in flocks and roost communally in trees. They fly mostly by soaring on warm air thermals. As with other storks, these are mostly silent birds, although during the breeding season they may make a range of loud raucous honks.
Breeding in the wild occurs during the wet season when food is easiest to find. Birds form lifelong partnerships. They will nest in colonies with other storks, usually up to 60 pairs but sometimes in more extensive groups. The pair usually build a platform of sticks and vegetation in trees or reedbeds. Three or four chalk-white eggs are laid and are incubated by both parents for about 25-30 days. Chicks are covered in black downy feathers and take 50-55 days to fledge.
African openbills usually cope well with life in an aviary. In collections open to the public they are not concerned by visitors and will move closer to them, presumably in the hope of being fed. In the wild they live for an average of seven to eight years, but in captivity this can be extended up to 23 years.
Gail Harland lives in Norfolk with her family and a variety of birds.
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