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African Openbill | Anastomus lamelligerus
Afrikaanse gaper | Picotenaza Africano
The African Openbill is a medium-sized, entirely dark stork whose bill mandibles meet only at the base and the tip, leaving a distinct gap between them. With this tool it specialises in large freshwater snails and freshwater mussels. It lives in flocks and after rains suddenly appears in areas where it has not been seen for years.
Voice
Mostly silent. At the colony a hoarse, rasping kwah-kwah and croaking; the pair clatters its bills softly.
No recording with a suitable Creative Commons licence is available for this species yet.
Identification
80–94 cm. The whole plumage is dark blackish-brown, glossed green and purple in good light; on the neck, mantle and breast the feathers end in narrow, shiny, horn-like strips that give the bird a shaggy, scaly look. The bill is thick, grey to horn-coloured, with the characteristic gap between the mandibles; in young birds the gap is absent or barely visible. The bare lores are grey, the legs black to dark grey, sometimes reddish in breeding birds. Juveniles are duller brown, without gloss. In flight a compact, dark stork with outstretched neck and projecting legs; it soars a great deal on thermals, often in flocks.
Confusion species
Black Stork Ciconia nigra has a white belly and a red bill and red legs. Abdim's Stork Ciconia abdimii has a white belly and back and a bluish face. Glossy Ibis Plegadis falcinellus has a thin, decurved bill and is much slimmer; Hadada Ibis Bostrychia hagedash also has a decurved bill. At close range the open bill rules out any confusion.
Habitat
Shallow freshwater marshes, floodplains, riverbanks, pans, rice fields and the margins of dams, wherever there are large snails (especially apple snails Pila) and mussels. It holds the shell with the bill tip and cuts the adductor muscle. Breeds colonially in trees over water or in reedbeds, often alongside herons and cormorants.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
Common in the north and east of the region: the Okavango Delta, the Linyanti and the Chobe in Botswana, the Caprivi in Namibia, Zambia, Malawi, the Zimbabwean lowveld and the Zambezi valley, the lowlands of Mozambique and Angola. In South Africa mainly in the lowveld of Limpopo and Mpumalanga, the Kruger National Park and northern KwaZulu-Natal; in wet years flocks move far onto the highveld and occasionally into the Cape. Eswatini in the lowveld. Beyond the region in Africa south of the Sahara, from Senegal to Sudan and Ethiopia, and on Madagascar.
- Resident
- Summer visitor (c. Oct–Mar)
- Winter visitor (c. Apr–Sep)
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
The Okavango and the Chobe River, especially in the rainy season and during the flood, when flocks forage on the floodplains. Look for birds probing deep into the water with the bill, and check resting birds for the gap in the bill; in flight the compact dark build and flocks soaring together give the species away.
Conservation status
Not threatened; common, with a large range. It is, however, sensitive to the drying-out and drainage of wetlands and to disturbance of breeding colonies. The strong fluctuations in numbers in the south are linked to rainfall and the availability of snails.
Scientific name
Anastomus lamelligerus | Temminck, 1823
Temminck described the species in 1823 and placed it straight away in the genus where it still stands. The genus Anastomus was introduced in 1791 by Bonnaterre. Anastomus comes from the Greek anastomoō, 'to furnish with a mouth or opening' — for the gaping bill whose mandibles meet only at the tip. lamelligerus comes from the Latin lamella, 'small plate', and -gerus, 'bearing' — for the glossy, horny plates at the tips of the neck and belly feathers. The specimen the first description was based on came from Senegal.