Yellow-billed stork (Mycteria ibis)
|Also known as:||African wood stork|
|Size||Height: 90 - 105 cm (2)|
Male weight: 2.3 kg (3)
Female weight: 1.9 kg (3)
The yellow-billed stork is classified as Least Concern (LC) on the IUCN Red List (1).
The yellow-billed stork (Mycteria ibis) is a large wading bird, which is most easily distinguished by its black tail and long neck (2) (3). It also has a characteristic yellow bill, with red skin at its base that extends onto its face. The bill is long, blunt and slightly downward-curved, perfectly adapted for catching its prey (2) (3).
This species has white feathers on its back, wings, breast and underside, which are suffused with pink. These contrast with the tail and flight feathers which are black, with the head being feathered to the top of the crown. The yellow-billed stork has long, brownish legs, used to stabilise the body while searching in water for prey (2) (4).
The colouration of the yellow-billed stork becomes more vivid throughout the breeding season. Its bill becomes a deeper yellow and the face a brighter red while the feathers are saturated with pink and the skin of the head is retracted, the area of visible red skin hidden beneath becoming larger. The ordinarily dull legs become a brighter red (2).
The male and female yellow-billed stork are similar in appearance, with the male being slightly larger (2).
The juvenile yellow-billed stork has an off grey-brown plumage, with a paler underside. It also has feathering on the head which extends further down onto its face than in the adult and its face is much duller (2) (5).
The yellow-billed stork does not generally vocalise, except for during the breeding season, when it will hiss and clap its bill (2).
The yellow-billed stork is native to Africa, where it ranges from Senegal in the east and Mauritania in the west and south to South Africa. It is a vagrant to the north of the Sahara including Morocco and Egypt (6).
The yellow-billed stork favours wetlands with a water depth of between 10 and 40 centimetres, with sandbanks and trees close by. It is frequently seen in margins of rivers and lakes, lagoons, large marshes, small pools, flooded grasslands, alkaline lakes, reservoirs, water holes and rice paddies, which all have optimum conditions for this species. It will avoid flooded areas as it is not able to feed in deep water (2) (6).
The diet of the yellow-billed stork comprises frogs, small fish, aquatic insects, worms, crustaceans, small mammals and birds (2) (6). This species is a patient feeder and will submerge its bill into the water until contact is made with its prey, at which point the head is flipped back and the catch swallowed. The yellow-billed stork has been known to wait while crocodiles or hippopotamus feed, before approaching to eat the organisms which have been stirred up (2).
During the night, the yellow-billed stork forms communal roosts at favoured sites surrounding the wetland, for example, on sandbanks or in trees. These roosts are often shared with other species (6).
The yellow-billed stork sometimes migrates to areas where the feeding conditions are more favourable, especially throughout periods of heavy rain. However, some populations are known to be sedentary (6). The most likely reason for this migration in this species is rising water levels creating poor hunting conditions (2).
Breeding in the yellow-billed stork is seasonal and dependent on the abundance of food. Breeding usually begins towards the end of the rainy season or at the beginning of the dry season, when food is readily available, the rainy season lasting from November through to May (6) (7). The yellow-billed stork breeds in colonies, although it will never form a flock of more than 50 individuals (6).
The nest of the yellow-billed stork consists of sticks positioned in a small tree over water, or elevated higher in a tree on dry land. There may be 10 to 20 pairs in each tree, sometimes of different species, with each nest separated by 1 to 3 metres (2) (6). The male and female yellow-billed stork share responsibility for incubating the eggs, brooding, guarding and feeding the young (2).
The German common name of this species is ‘Nimmersatt’, meaning never full, due to the eating habits of the nestling, it increases from 60 grams to 500 grams in weight within the first ten days of life (2).
The yellow-billed stork is known to be under pressure from poaching and reduction of available habitat; however, no threat is thought to be currently affecting the overall population size (2).
The yellow-billed stork is listed under the African-Eurasian Waterbird Agreement (AEWA), which calls upon parties to undertake conservation actions to help protect and conserve bird species that are dependent on wetlands for at least part of their annual cycle (8). There are no other specific conservation methods currently known to be in place for this species.
Find out more about the yellow-billed stork:
BirdLife International - Yellow-billed stork
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- Alkaline: having a pH greater than 7.0.
- Crustaceans: diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
- Flight feathers: the feathers at the end of the wing, involved in flight.
- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
IUCN Red List (October, 2011)
- Hancock, J. and Kushlan, J.A. (2010) Storks, Ibises and Spoonbills of the World. Christopher Helm Publishers, London.
- Sinclair, I., Hockey, P.A.R., Arlott, N. (2007) The Larger Illustrated Guide to Birds of Southern Africa. Struik Publishers, Cape Town.
- Redman, N., Fanshawe, J. and Stevenson, T. (2009) Birds of the Horn of Africa: Ethiopia, Eritrea, Djibouti, Somalia and Socotra. A & C Black, London.
- Sinclair, I. and Davidson, I. (2006) Southern African Birds: A Photographic Guide. Struik Publishers, Cape Town.
BirdLife International - Yellow-billed stork (October, 2011)
- Nanda, S. and Warms, R. (2010) Cultural Anthropology. Cengage Learning, California.
- African-Eurasian Waterbird Agreement (October, 2011) http://www.unep-aewa.org/