African Openbill Anastomus lamelligerus Scientific name definitions

80–94 cm; 628–1400 g. Males average larger. Mantle and breast glossy green, purple or brown; gap in bill 6 mm wide at most. Immature  duller, bill almost straight. Race madagascariensis  smaller, with thinner bill, which has more pronounced longitudinal ridges.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Mainly found in extensive freshwater wetland habitats , typically in marshes and swamps, backwaters and margins of lakes or rivers, paddyfields and floodplains; sometimes in moist savanna or burnt grassland, occasionally in forest clearings.

Most breed in E & S Africa, chiefly late in wet season and early in dry season, when their snail prey is most readily available. Some then migrate N of equator, where the species is widespread during dry season, in Oct–Apr (1 Dodman, T. and Diagana, C. (2007). Movements of waterbirds within Africa and their conservation implications. Ostrich. 78(2): 149–154. Close ). It is uncommon to rare in coastal and western W Africa; occurrences in Senegal have declined and species is not included on Mauritanian list (2 Borrow, N., and R. Demey (2001). Birds of Western Africa. Christopher Helm, London, UK. Close , 3 Isenmann, P., M. Benmergui, P. Browne, A. D. Ba, C. H. Diagana, Y. Diawara, and Z. El Abidine ould Sidaty (2010). Oiseaux de Mauritanie [Birds of Mauritania]. Société d’Études Ornithologiques de France, Paris, France. Close ). Those that breed in S Africa are largely resident. Irregular large-scale movements reported in response to local conditions. Birds have reached Zanzibar and Pemba on rare occasions (4 Archer, A. L. and Iles, D. B. (1998). New bird records for Unguja (Zanzibar Island). Bulletin of the British Ornithologists' Club 118(3): 166–172. Close ). Vagrant individual reached the Palearctic at Luxor, Egypt (5 Steffe, B. (2010). African Openbill at Luxor, Egypt, in May 2009. Dutch Birding. 32: 254–256. Close ).  

A specialist predator on aquatic snails  (Pila, Lanistes ovum) which it finds in muddy waters or buried in mud. It also frequently consumes freshwater mussels (Ampullaria). In Uganda recorded taking the terrestrial snail Limicolaria martensiana.. Occasionally takes other prey, including frogs, crabs, worms, fish and insects. It employs a highly specialised technique boh for extracting snails from shells and also for opening bivalves; the sharp tip of the lower mandible is used to cut prey muscles (see family introduction). It sometimes associates with hippopotami, which may expose snails when churning up water, mud or vegetation.

Largely silent away from the breeding colonies. Around nest, utters loud raucous, sonorous honks “horrh-horrh”. Bill-clattering as in other storks physically impossible, but during copulation similar sounds are produced by rattling bills sideways against each other. Young beg for food by calling  incessantly “kek-kek-kek-kek...kek-kek-kek-kek...”.

Breeding sometimes opportunistic, both in timing and location. For example, egg-laying has been reported in nearly every month in Zambia (6 Benson, C. W., R. K. Brooke, R. J. Dowsett, and M. P. S. Irwin (1971). The Birds of Zambia. Collins, London, UK. Close ). However, it most commonly commences late in rainy season, which is probably when snails are most readily available. Typically nests in trees, in colonies of various sizes, frequently over water. Some nest in reedbeds. Nest is small, only c. 50 cm wide; a platform of sticks and reeds. Clutch size averages 3–4 eggs (2–5). Incubation estimated at 25–30 days; chicks have black down and a normal-shaped bill, curvature developing over several years. Fledging estimated at 50–55 days.

Not globally threatened (Least Concern). Thought to be declining overall, although some populations may be stable (7 Delany, S., and D. Scott (2006). Waterbird population estimates. Fourth Edition. Wetlands International, Wageningen, The Netherlands. Close ). Common in suitable habitat throughout its range, often abundant around breeding colonies. A colony of > 5000 pairs in 1968, in Tanzania, was then the largest known colony. Threats include habitat loss and the effects of insecticides used to kill mosquitoes (8 Hockey, P.A.R., Dean, W.R.J., Ryan, P.G. and Maree, S. (2005). Roberts Birds of Southern Africa. 7th edition. Black Eagle Publishing, Cape Town. Close ). It is known to be hunted and traded for traditional medicine in Nigeria (9 Nikolaus, G. (2001). Bird exploitation for traditional medicine in Nigeria. Malimbus 23:45–55. Close ). In Madagascar, endemic race madagascariensis has declined in both range and numbers in recent years, due to destruction of colonies by villagers. Numbers using the Manambolomaty Lakes Ramsar site in the NE have been reported to have declined on account of habitat destruction there (10 Rabirasoa, R. (2001). Variation de la population des oiseaux d'eau dans le complexe des lacs de Manambolomaty, un site Ramsar de Madagascar. Ostrich. Supplement 15: 83–87. . Close ).