Anastomus lamelligerus (African
openbill, Openbilled stork)
Oopbekooievaar [Afrikaans]; isiQhophamnenke [Zulu];
Etongorokofu [Kwangali]; Mukyindlopfu [Tsonga]; Afrikaanse gaper [Dutch];
Bec-ouvert africain [French]; Klaffschnabel [German]; Bico-aberto [Portuguese]
Life
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Deuterostomia > Chordata >
Craniata > Vertebrata (vertebrates) > Gnathostomata (jawed
vertebrates) > Teleostomi (teleost fish) > Osteichthyes (bony fish) > Class:
Sarcopterygii (lobe-finned
fish) > Stegocephalia (terrestrial
vertebrates) > Tetrapoda
(four-legged vertebrates) > Reptiliomorpha > Amniota >
Reptilia (reptiles) >
Romeriida > Diapsida > Archosauromorpha > Archosauria >
Dinosauria
(dinosaurs) > Saurischia > Theropoda (bipedal predatory dinosaurs) >
Coelurosauria > Maniraptora > Aves
(birds) > Order: Ciconiiformes > Family: Ciconiidae
Distribution and habitat
Occurs across much of sub-Saharan Africa, from Mali to
Ethiopia south to South Africa. In southern Africa, it is locally common in
Mozambique, Zimbabwe, eastern South Africa, northern Botswana and northern
Namibia. It generally prefers wetlands, such as
temporarily flooded pans, flood plains, swamps, marshes, ponds, streams, river
shallows, dams, rice fields, lagoons, lake edges and intertidal flats.
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Distribution of African openbill in southern Africa,
based on statistical smoothing of the records from first SA Bird Atlas
Project (©
Animal Demography unit, University of
Cape Town; smoothing by Birgit Erni and Francesca Little). Colours range
from dark blue (most common) through to yellow (least common).
See here for the latest distribution
from the SABAP2. |
Predators and parasites
Movements and migrations
Largely resident and sedentary, although it may
also undertake nomadic movements, sometimes migrating in flocks away
from arid regions at the onset of the dry season.
Food
It almost exclusively eats snails and bivalves, as its bill
is specially adapted to extract the meat without even breaking the shell. It
often forages alongside
African sacred
and Hadeda ibises,
typically wading through shallow water with floating plants, probing the water
and extracting a snail. Once it has done so it holds it against the ground,
using its razor sharp bottom mandible to sever the muscle that connects the
snail to its shell, vigorously shaking its head until the snail body is
extracted and promptly swallowing; the whole process can take under 15 seconds.
It struggles to open other types of molluscs (such as bivalves), either failing
completely or taking at least
ten minutes for to pry open the shell. Consequently it may place them in
groups of roughly 50-60 on the shoreline, waiting for the sun to kill them so
that they release their hold on the shell. The following food items have been recorded
in its diet:
- snails
- Bellamyia unicolor
- Pila
- land snails
- Limicolaria martensiana
- Lanistes ovum
- bivalves
- Coelatura mossambicensis
- Corbicula fluminali
- Chambardia wahlbergi
- Mutela zambesiensis
- frogs
Breeding
- Monogamous, breeding in colonies of under 60, rarely up to
170 pairs, with 4-20 nests per tree. It sometimes joins mixed-species
colonies along with cormorants,
herons,
African spoonbills,
African darters and
storks. Each male selects a nest site
and displays on it, while females move from tree to tree and attempt to
approach a male's nest site. The male repeatedly drives them away, sometimes
violently, but eventually he allows the female to copulate with him.
- The nest is built by both sexes in roughly a week, consisting of a thin
platform of sticks and twigs, lined with leaves, grass, sedges and other
aquatic plants, such as Antelope grass (Echinochloa), reeds (Phragmites)
and knotweed (Polygonum senegalense). It is typically placed in a
tree or bush on an island or partially submerged area.
- Egg-laying season is from August-May, peaking from January-March.
- It lays 3-5 eggs, which are incubated by both sexes for about 21-30
days.
- The chicks are fed by both parents on a diet of shelled snails, since
even at 42 days old they still cannot extract the meat from the shell. They
leave the nest at about 50-55 days old.
Threats
Not globally threatened, although it is now classified as
Near-threatened in South Africa, largely due to pesticides added to
water to control mosquito populations, habitat loss and entanglement in fishing
lines.
References
-
Hockey PAR, Dean WRJ and Ryan PG 2005. Roberts
- Birds of southern Africa, VIIth ed. The Trustees of the John Voelcker
Bird Book Fund, Cape Town.
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