Threskiornis aethiopicussacred ibis

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Geographic Range

Sacred ibises are native and abundant in sub-Saharan Africa and southeast Iraq. There are introduced populations in Spain, Italy, France, and the Canary Islands from individuals that escaped from captivity and began breeding successfully. (Cramp and Simmons, 1977; Yesou and Clergeau, 2005)

Habitat

Sacred ibises inhabit a wide range of habitats, although generally they are found in close proximity to rivers, streams, and coastlines. Their native range is sub-tropical to tropical, but they are found in more temperate areas where introduced. They often nest on rocky marine islands and have adapted to living in towns and villages. (Cramp and Simmons, 1977; Kopij, 1999; Yesou and Clergeau, 2005)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • coastal

Physical Description

Pure to dirty white feathers cover most of the body. Blue-black scapular plumes form a tuft that falls over the short, square-shaped tail and closed wings. The flight feathers are white with dark blue-green tips. Sacred ibises have long necks and bald, dull grey-black heads. The eyes are brown with a dark red orbital ring and the bill is long, downwardly curving, and with slit-like nostrils. Red bare skin is visible on the side of the breast and on the underwings. The legs are black with a red tinge. There is no seasonal variation or sexual dimorphism other than that males are slightly larger than females.

Juveniles have feathered heads and necks that are mottled white with black streaks. Their scapular feathers are greenish-brown and there is more black on their outer primaries and primary coverts. The underwing coverts have dark streaks. The tail is white with brown corners. (Cramp and Simmons, 1977)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • Average mass
    1.5 kg
    3.30 lb
  • Range length
    65 to 75 cm
    25.59 to 29.53 in
  • Range wingspan
    112 to 124 cm
    44.09 to 48.82 in

Reproduction

Sacred ibises form seasonally monogamous breeding pairs that nest in large nesting colonies. (Cramp and Simmons, 1977; Kopij, 1999)

During the breeding season large groups of males select a spot to settle and form pairing territories. In these territories males stand with wings held downwards and rectrices spread. In the following several days females arrive in the nesting colony, along with more males. Newly arriving males go to the established territories of settler males and compete for the territory. Fighting males may strike at each other with their bills and make squealing noises. Females choose among males and their pairing territories and pairs are formed. Once the pair is formed, the couple moves to a nearby nesting area selected by the female. Fighting behavior may continue in the nesting area between neighboring individuals of either sex. Individuals will stand with wings outstretched and head lowered with bill open towards other individuals. Individuals that are very close to each other may adopt a similar stance, but with bill pointed upwards, nearly touching, while making calls. (Cramp and Simmons, 1977; Kopij, 1999)

During pair formation the female approaches the male and, if she is not chased away, they face one another and bow with necks outstretched forward and towards the ground. After this they assume a standing posture and intertwine their necks and bills. This may be followed by more bowing or extensive self-preening. The pair then establishes a nest territory where copulation occurs. During copulation, females crouch so males may straddle them, the male may grab the females bill and shake it side to side. After copulation the pair again assumes a standing position and extensively preen themselves at the nest site. (Cramp and Simmons, 1977; Kopij, 1999)

Sacred ibises breed yearly in large nesting colonies. In Africa breeding occurs from March to August, in Iraq breeding is reported from April to May. Females lay from 1 to 5 (average 2) eggs, which are incubated for about 28 days. The eggs are oval shaped or slightly round, with a rough texture. The eggs are dull white with a blue tinge and sometimes dark red spots. Eggs are from 43 to 63 mm. Fledging occurs 35 to 40 days after hatching and the young become independent soon after fledging. (Cramp and Simmons, 1977; Kopij, 1999)

  • Breeding interval
    Sacred ibises breed once yearly.
  • Breeding season
    In Africa breeding occurs from March to August, in Iraq breeding is reported from April to May.
  • Range eggs per season
    1 to 5
  • Average eggs per season
    2
  • Range time to hatching
    21 to 29 days
  • Average time to hatching
    28 days
  • Range fledging age
    35 to 40 days
  • Range time to independence
    44 to 48 days

Incubation lasts for around 21 to 29 days, with most incubated around 28 days by both male and female, alternating at least once every 24 hours. After hatching one parent is present at the nest at all times for the first 7 to 10 days. The young are fed many times a day by partial regurgitation from parents. Young leave the nests after 2 to 3 weeks and form groups close to the colony. They are fed by parents once a day after leaving the nest. The fledgling period lasts from 35 to 40 days and individuals leave the colony at 44 to 48 days after hatching.

After eggs hatch, the parents identify and feed only their own offspring. When parents return to feed offspring, they give a short “keerooh” call. The offspring recognizes the parental call and may run, jump, or fly to the parent for food. If other young approach the parent, they will be chased away. When the offspring learns to fly, it may circle the colony until the parent returns to feed it, or even chase the parent around before feeding. (Cramp and Simmons, 1977; Kopij, 1999)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

Lifespan/Longevity

Sacred ibises may live up to 20 years.

  • Typical lifespan
    Status: wild
    20 (high) years

Behavior

Sacred ibises form large colonies during the nesting season. They also flock for foraging and roosting, with communal roosts of up to 300 individuals being reported. They forage over large areas and may make seasonal migrations to foraging and breeding sites. (Cramp and Simmons, 1977)

Communication and Perception

Sacred ibises are generally quiet birds. During the breeding season they produce a variety of vocalizations. In antagonistic situations, both sexes utter a variety of squeals, moans, and wheezes, sometimes described as: “whoot-whoot-whoot-whooeeoh” or “pyuk-pyuk-pek-pek-peuk”. Females make a series of “whaank” noises after the nest is built to attract the male, this is usually followed by copulation. Adults make a “turrooh” or “keerrooh” to call their offspring back to the nest. Adults make a high pitched “chrreeee-chree-ah-chreeee” to call offspring for feeding. They have also been observed making a loud croak during flight. (Cramp and Simmons, 1977)

Food Habits

Sacred ibises feed during the day primarily in flocks by wading in shallow wetlands. Occasionally they will feed on dry land close to water. They may fly a distance of 10 km to foraging grounds. They feed primarily on insects, arachnids, annelids, crustaceans, and mollusks. They have been observed eating frogs, reptiles, fish, young birds, eggs, and carrion as well. In more cultivated areas, they have been known to eat human refuse. This has been observed in France where they are becoming an invasive pest species. (Cramp and Simmons, 1977; Yesou and Clergeau, 2005)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • fish
  • eggs
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans

Predation

There are few reports of predation on sacred ibises. As adults these birds are very large, discouraging most predation. Young sacred ibises are guarded carefully by their parents, but may be subject to predation by large raptors.

Ecosystem Roles

Sacred ibises are important wading birds throughout their range in Africa, consuming a wide variety of smaller animals, keeping their populations in check. In Europe, their adaptable nature has made sacred ibises an invasive species, sometimes feeding on rare birds. (Yesou and Clergeau, 2005)

Economic Importance for Humans: Positive

Ancient Egyptians revered sacred ibises. They mummified many of these birds and buried them in the tombs of deceased pharaohs, though they are now rare in Egypt. Sacred ibises are also important members of native ecosystems. (Cramp and Simmons, 1977)

Economic Importance for Humans: Negative

Sacred ibises do not impact humans directly, but where they are introduced they may become a nuisance or may prey on bird species that are threatened or protected. (Yesou and Clergeau, 2005)

Conservation Status

Sacred ibises are not considered threatened in their native range. They have become a conservation problem in Europe, where they have been reported feeding on threatened native species as well as encroaching on the habitats of native species. This has become a concern for European conservationists trying to protect native threatened species. (Yesou and Clergeau, 2005)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Charlie Ramsey (author), Northern Michigan University, Alec R. Lindsay (editor, instructor), Northern Michigan University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Cramp, S., K. Simmons. 1977. Handbook of the Birds of Europe, the Middle East, and North Africa: Vol. 1. Oxford: Oxford University Press.

Kopij, G. 1999. Breeding Ecology of the Sacred Ibis Threskiornis aethipicus in the Free State, South Africa. South African journal of Wildlife Research, 29/2: 25-30.

Yesou, P., P. Clergeau. 2005. Sacred Ibis: a New Invasive Species in Europe. Birding World, 18/12: 517-526.