American White Ibis

AMERICAN WHITE IBIS

CICONIIFORMES Family: Threskiornithidae Genus: Eudocimus Species: albus

Range: Southeastern United States south to northern Colombia, Ecuador and Venezuela Habitat: shallow coastal marshes, wetlands and mangrove swamps with salt, brackish or fresh water. Niche: Diurnal, terrestrial/aquatic, carnivorous Wild diet: small aquatic prey such as insects, crayfish, frogs and small fishes Zoo diet: Life Span: (Wild) oldest recorded 16 years (Captivity) 20 years Sexual dimorphism: males are generally larger than the females and have longer bills Location in SF Zoo: South American Tropical Rainforest and Aviary

APPEARANCE & PHYSICAL ADAPTATIONS:

The White Ibis is white with long scarlet legs, scarlet facial skin, and a scarlet decurved bill with black wing tips that are usually only visible in flight. Juvenile birds are dark overall. They become increasingly pale over the first year or so, molting into white adult plumage by early in their second year. The bill, face, and legs of young birds change similarly, from dark, to orange, to the red of adulthood. During the breeding season, their Weight: 26.5–37 oz legs, face and beaks turn from pale orange to bright pink. Length: 22–26.8 in Height: 2 ft The ibis is a tactile, non-visual forager whose main foraging behavior is Wingspan: 38 in probing its beak into the water to feel for and to capture its prey. It sweeps its long bill back and forth across the bottom to pick out suitable food items. Their beaks are sensitive to movement and can detect prey through mud and water. Then, it cleans its prey in the water before swallowing it. The bird's nostrils are at the base of the bill, so the ibis can breath while sticking its bill in the water or mud.

STATUS & CONSERVATION

Not globally threatened. The American White Ibis is classed as Least Concern on the IUCN Red List. It is considered a game bird throughout its range. They are threatened by habitat loss and destruction of colony sites by humans. Nesting adults are particularly sensitive to disturbance, and eggs and chicks left alone due to human intrusion are susceptible to predation. Since this species nests in large groups, nest disturbance can have devastating effects on a colony.

COMMUNICATION AND OTHER BEHAVIOR

White Ibis have a harsh and nasal call “hunk-hunk-hunk-hunk”. It is an alarm call uttered by the male. The female squeals. They often utter a soft grunting “croo-croo-croo” while foraging.

The White Ibis is highly gregarious, living in flocks and nest in huge colonies near water. They will defend their small nesting territory and show some aggression while mating, jabbing at rivals or catching wing or head’s opponent in their bill. Juveniles are usually in separated flocks.

The White Ibis flies with neck and legs outstretched, often in long, loose lines or 'V' formations, which may improve the birds' aerodynamic efficiency. These lines fly in an undulating pattern as they alternately flap and glide.

COURTSHIP AND YOUNG

The White Ibis breeds in colonies, where nests can number in the tens of thousands. Courtship displays include preening, leaning over, and with a twig in the bill, pointing bill skywards and lowering head onto back. The female chooses the nest site and builds the nest, usually in the branches of a tree or shrub. The male assists by bringing her nesting material, occasionally stolen from a neighbor. During incubation, the male aggressively defends his nest and mate from both predators and other ibises. The nest is a platform made with sticks or reeds, and sometimes lined with fresh leaves.

Both parents share in the incubation and feeding of the young by regurgitation. The chicks become independent at about 7 weeks and form flocks of their own.

Incubation: 21 – 23 days Sexual Maturity: 2 years # of eggs: 2 - 3 Fledging: 45 to 55 days

MISCELLANEOUS

This species is very closely related to the Scarlet Ibis and is sometimes considered conspecific with it. In Venezuela, where their ranges overlap, the White Ibis hybridizes with Scarlet Ibis (Eudocimus ruber), giving various shades of pink and scarlet in young bird’s plumage.