- Common Name
- Genus Species
- 29 species
- Birds in this order have spindly legs, long necks, and long bills. Ibises tend to have slender, down-curved bills.
- White ibises (Eudocimus albus) are about 58 to 69 cm (23 to 27 in.) tall, with a wingspan of 97 cm (38 in.). The giant ibis (Thaumatibis gigantean) is 102 to 106 cm (40 to 42 in.) tall.
- The white ibis weighs approximately 1.35 kg (3 lbs.).
- The hermit ibis (Geronticus eremita) inhabits the drier areas of North Africa and the Middle East and feeds on beetles and other small animals. White ibises eat fishes, insects, aquatic invertebrates, small snakes, and plant matter. Other types of ibises may eat seeds, fruits, mollusks, and frogs.
- Most ibises prefer to nest in trees. Exceptions include the hermit ibis, which nests on cliffs, and the sacred ibis (Threskiornis aethiopica), which build their nests on the ground. Black ibises (Pseudibis papillosa) may be found in groups of only 2 to 3 when they nest while the sacred ibis may form huge breeding colonies of more than 10,000 individuals. Ibises may share their colony sites with other birds including herons and egrets. White ibises lay 2 to 5 eggs during nesting season. The eggs take about 21 to 23 days to incubate. The young fledge in approximately 28 to 35 days. Both the male and female take turns in guarding the nest site until the chicks are large enough to defend themselves. In addition, both parents help feed the chicks.
- Sexual Maturity
- Approximately 4 to 5 years; juvenile white ibises are brown until maturity
- Life Span
- Up to 20 years
- Varies by species
- Ibises generally live in tropical shores, marshes, mudflats, and lakes
- Varies by species
- IUCN: 3 species listed as Endangered, 3 are listed as Critically Endangered
CITES: 2 species Appendix I; 2 species Appendix II; 2 species Appendix III
USFWS: 4 species listed as Endangered
Ibises have curved, slender bills that they use to probe into shallow water, mud or grass when foraging.
Ibises are gregarious birds that live, travel and breed in flocks. In flight, they form diagonal lines or V-formations. This formation decreases wind resistance for trailing birds. When the leader of the pack tires, it falls to the back of the formation and another ibis takes its place at the front.
These are rather quiet birds, only grunting or croaking on breeding grounds.
Ibises are an ancient species with fossil records going back 60 million years.
Ecology and Conservation
Habitat destruction, poaching, and insecticide use such as DDT have all caused the decline of several ibis species.
Ibises are not only scavengers at rubbish dumps or sewage works, but also move around croplands helping egrets and others to rid the area of insect pests. The adaptability of the ibis to many different food sources ensures its success as a species.
Because of their role in helping to control crop pests, ibises are very valuable to farmers. However, agricultural pesticide usage has endangered the birds in several locations.
In ancient Egypt, the sacred ibis was once held in high reverence. Thoth, the Egyptian god of knowledge, was believed to take the form of an ibis. In honor of Thoth, thousands of sacred ibises were mummified and kept in Egyptian temples as pets. Ironically, habitat destruction has depleted the sacred ibis in Egypt today.
Humans are the primary threat to these birds, not only by habitat encroachment but also from hunting. Scarlet ibises (Eudocimus ruber), for example, are hunted for their vivid red plumage despite the fact that they are the national bird of Trinidad.
Gotch, A.F. Birds - Their Latin Names Explained. Poole, Dorst: Blandford Press, 1981.
Perrins, Dr. Christopher. Birds: Their Life, Their Ways, Their World. New York: The Reader's Digest Association, Inc. 1979.
Chaffee Zoological Gardens of Fresno. chaffeezoo.org/zoo/animals
BirdLife International 2010. The IUCN Red List of Threatened Species 2010: e.T22697531A34052704. Downloaded on 11 March 2020.
fws.gov/endangered. Accessed 11 March 2020.