African sacred ibis (Threskiornis aethiopicus)

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African sacred ibis wading through water
IUCN Red List species status – Least Concern LEAST
CONCERN

Top facts

  • Introduced populations of the African sacred ibis in Europe are thought to have been established after escaping from zoos.
  • A long-living species, the African sacred ibis can live for over 20 years.
  • There are three different subspecies of African sacred ibis, which differ in appearance and distribution.
  • An opportunistic feeder, the African sacred ibis takes a wide range of prey.
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African sacred ibis fact file

African sacred ibis description

KingdomAnimalia
PhylumChordata
ClassAves
OrderCiconiiformes
FamilyThreskiornithidae
GenusThreskiornis (1)

The distinctive African sacred ibis (Threskiornis aethiopicus) is characterised by its large size, primarily white plumage and conspicuous black head and neck, which lack feathers (2) (4) (5). The black-tipped wings have areas of bare red skin on the upper and lower surfaces, and there are also bare red areas on the breast and sides of the body (2). The long black legs and feet also lack feathers (2) (4).

One of the most prominent features of this bird is its long, black, downcurved bill (2) (5), which has a neck sac positioned underneath its lower surface and is used for probing into soft mud and sand in pursuit of prey. The eyes of the African sacred ibis are brown or red-brown and the lower eyelid is pink (4)

The male and female African sacred ibis are similar in appearance, although males are larger than females and frequently have a longer bill. During the breeding season the differences between the sexes become more apparent, as the shoulder area of the male develops a blue metallic sheen and the bare skin on the underside of the wings and breast is flushed vibrant red (4), while the black on the tips of the wings becomes more extensive (2). The dull black skin of the head and neck becomes shiny and the legs turn red or dark red. A red ring also develops around the iris (4).

The juvenile African sacred ibis is very different in appearance to the adult. The head and neck are covered in a fine, black down and there is a white spot on the crown of the head. The juvenile’s legs and feet are grey-black and the tips of the wings are brown-black (2). The African sacred ibis does not gain its full adult plumage until it is around three years old (4).

The African sacred ibis has three recognised subspecies: Threskiornis aethiopicus aethiopicus, Threskiornis aethiopicus bernieri and Threskiornis aethiopicus abbotti. The three subspecies differ in their distribution, as well as in their appearance, with T. a. bernieri and T. a. abbotti having a thinner bill, no neck sack and fewer black flight feathers than the nominate subspecies (4) (6). The subspecies also have different iris colouration, as T. a. abbotti has a blue iris, whereas T. a. bernieri has a pale blue or white iris (2) (4) (6). T. a. abbotti can also be distinguished by the black stripe on the underside of its wings. Both of these subspecies are smaller in size than the nominate subspecies (4).

The vocalisations of the African sacred ibis are highly variable, with harsh croaking noises being made during flight and squeaking ‘whoot-whoot-whoot-whooeeoh’ or ‘pyuk-pyuk-peuk-peuk-pek-peuk calls made while individuals are on their breeding grounds. Vocalisations are also used by females to attract males and during copulation (2).

Size
Length: 65 - 89 cm (2)
Wingspan: 112 - 124 cm (2)
Weight
c. 1530 g (2)
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African sacred ibis biology

An opportunistic, mainly carnivorous feeder (5), the African sacred ibis takes a range of insects, worms, bird and reptile eggs, crustaceans, frogs, lizards, small mammals and carrion (2) (4) (6). It uses its long bill to probe into mud and soil to capture prey (2) (4), as well as chasing moving prey with its wings half open (4). Certain populations forage around rubbish dumps and slurry pits (2) (4), with some becoming reliant on these areas as a food source (2). The African sacred ibis usually forages in groups of between 2 and 20 individuals, although groups of up to 500 have been recorded (2).

The breeding season of the African sacred ibis differs geographically (4), but usually begins during or shortly after the rainy season (2) (4) (6). Large, mixed-species colonies are formed, which include between 50 and 2,000 breeding pairs (4) (6). The male collects the nest materials and the female assembles the structure (2). The nest is a large platform of sticks and branches, which is lined with leaves and grass and placed in a tree, bush or on the ground (2) (4) (5) (6). When nest materials are in short supply, males may attempt to steal objects from other individuals within the colony (4).

Once the nest is complete, the female African sacred ibis then lays an average clutch of two or three eggs (2), which have a rough surface and are dull white with a blue or green tinge and red-brown spots (2) (4). The male and female take turns to incubate the eggs, usually changing over every 24 hours. The incubation period lasts around 28 days, after which the nestlings are fed and cared for by both adults (2) (4), with one finding food while the other remains at the nest (4). The nestlings eventually fledge the nest when they are between 35 and 40 days old (2) (4). A fledgling will leave its colony when it is between 44 and 48 days old (2). The pair bond between the male and female African sacred ibis lasts for one breeding season (2).

A gregarious species, the African sacred ibis roosts in large numbers at communal roosting sites, which are usually located on islets in rivers or in trees (4) (6).

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African sacred ibis range

The three subspecies of the African sacred ibis differ in their distribution, with the range of T. a. aethiopicus spreading north from South Africa to Sudan and Niger. This species is absent from certain regions within Cameroon, Congo, Gabon and the Central African Republic, as well as areas on the west coast of Africa including Namibia, Ghana, Côte d’Ivoire and Liberia (2) (6). This species was formerly found in Egypt, although it is now thought to be regionally extinct there (6). T. a. abbotti and T. a. bernieri have very limited distributions, being endemic to Aldabra and Madagascar, respectively (2).

T. a. aethiopicus also has introduced populations in southwest Asia, France, Russia and the United States, which are thought to have been established when individuals escaped from zoos (2) (4) (6). There have also been sightings of individuals in the United Kingdom (5).

As an intra-African migrant, T. a. aethiopicus makes short seasonal migrations to suitable breeding grounds, with the direction of travel depending on the location of the individual (2) (6). If the individual is found to the north of the equator, it will migrate northwards, whereas if it is found to the south of the equator, it will migrate southwards. Some populations are also known to be sedentary, especially at the southern limit of the African sacred ibis’s range (2) (6). Although T. a. aethiopicus is known to migrate, T. a. bernieri and T. a. abbotti do not show any signs of migration from their island habitats (4).

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African sacred ibis habitat

The African sacred ibis is found in a wide range of habitats, including freshwater wetlands, salt pans, dams, mangroves, rivers in open forested areas, and cultivated fields. Human environments are also inhabited by this species and it is frequently found around refuse dumps, abattoirs and farmyards (2) (4) (5) (6). In Zambia, it has been recorded up to elevations of 1,800 metres (2).

Habitats can vary between subspecies, with T. a. bernieri generally inhabiting estuarine and coastal areas (6).

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African sacred ibis status

The African sacred ibis is classified as Least Concern (LC) on the IUCN Red List (1), and is listed on Appendix III of CITES (3).

IUCN Red List species status – Least Concern

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African sacred ibis threats

Although it is a highly adaptable species, the African sacred ibis is threatened throughout its range by disturbance to its nesting and feeding sites, as well as by wetland drainage and hunting (2) (4). Populations of T. a. abbotti and T. a. bernieri have declined due to overharvesting and other human disturbances, and a breakout of avian botulism could threaten all subspecies of African sacred ibis in the future (6).

As a carnivorous, opportunistic feeder this species could have negative localised impacts on native prey species in its introduced range, especially native birds whose eggs and young may be at risk of predation. The African sacred ibis may also compete with other birds for nest sites. There have also been concerns about public health issues in non-native areas due to this species’ tendency to forage around rubbish dumps (5)

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African sacred ibis conservation

The African sacred ibis is listed on Appendix III of the Convention on International Trade in Endangered Species (CITES) in Ghana, which helps to regulate the number of African sacred ibis that can be exported (3). Legal protection and management of T. a. abbotti has improved breeding success within its habitat and its population size has increased (2). It has been recommended that the small population in Madagascar needs protection to avoid the negative effects of overharvesting (4).

View information on this species at the UNEP World Conservation Monitoring Centre.
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Find out more

Find out more about the African sacred ibis:

 More information on the African sacred ibis as an invasive species:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Avian botulism
A paralytic, often fatal disease of birds caused by the ingestion of toxin produced by the bacterium Clostridium botulinum.
Carnivorous
Feeding on flesh.
Carrion
The flesh of a dead animal.
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.
Endemic
A species or taxonomic group that is only found in one particular country or geographic area.
Flight feathers
The feathers at the end of the wing, involved in flight.
Incubate
To keep eggs warm so that development is possible.
Incubation
The act of incubating eggs; that is, keeping them warm so that development is possible.
Nominate subspecies
When a species is divided into subspecies, the originally described population is classified as the nominate subspecies. Indicated by the repetition of the species name; for example, Cyclura nubila nubila is the nominate subspecies of the Cayman Islands ground iguana, Cyclura nubila.
Subspecies
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
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References

  1. IUCN Red List (October, 2013)
    http://www.iucnredlist.org/
  2. del Hoyo, J. and Matheu, E. (1992) Handbook of the Birds of the World. Volume 1:Ostrich to Ducks. Lynx Edicions, Barcelona. Available at:
    http://www.hbw.com/
  3. CITES (October, 2013)
    http://www.cites.org/
  4. Hancock, J.A., Kushlan, J.A. and Kahl, M.P. (1992) Storks, Ibises and Spoonbills of the World. Academic Press, London.
  5. GB Non-native Species Secretariat (NNSS): Factsheet - African sacred ibis (October, 2013)
    https://secure.fera.defra.gov.uk/nonnativespecies/factsheet/factsheet.cfm?speciesId=3537
  6. BirdLife International - African sacred ibis (October, 2013)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=3794
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Image credit

African sacred ibis wading through water  
African sacred ibis wading through water

© Erwan Balança / Biosphoto

Biosphoto
16 rue Velouterie
Avignon
84000
France
Tel: +33 (490) 162 042
Fax: +33 (663) 208 434
http://www.biosphoto.com/

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