White-faced Ibises forage in shallow wetlands, usually among short plants such as sedges, spikerush, glasswort, saltgrass, and greasewood. Salt, brackish, and freshwater marshes all provide foraging habitat. They also frequent wet agricultural fields with low plant cover, including alfalfa, barley, wheat, oats, and rice, along with livestock pastures and hayfields. For nesting, White-faced Ibises select shallow marshes with scattered areas of taller emergent vegetation such as cattail, bur-reed, or bulrush. In California, they sometimes nest in stands of saltcedar (tamarisk) that have been flooded, while in the western Gulf coast, they often nest in Phragmites stands or on bare ground. Migrants might be attracted to almost any wet agricultural field or marsh, and in some cases, they have turned up in wooded streams, impoundments, grassy fields next to playas, and sewage ponds. Wintering White-faced Ibises use much the same habitats as nesting and migrating birds, mostly in the southern tier of U.S. states and farther south. In Mexico, they winter in wetlands of the central plateau and in valleys of the higher mountain ranges among marshes or agricultural fields.Back to top
White-faced Ibises eat mostly invertebrates such as earthworms, crayfish, and insects. They are both visual and tactile feeders, foraging by lowering their bills into the water or mud to feel for prey, or by swinging the bill side to side through water. They also pick at prey near the water’s surface or on vegetation. They forage mostly in moist soil or wetlands, though they have been observed probing gopher mounds in dry fields. The bulk of their diet consists of earthworms, crustaceans (particularly crayfish), spiders, snails, clams, leeches, and various insects and their larvae—dragonflies, crickets, grasshoppers, midges, beetle, flies, and bugs. They take vertebrate prey such as fish, frogs, and even small rodents as well, sometimes rinsing larger prey items in water before consuming them.. Unlike Glossy Ibis, which eats large quantities of rice, White-faced seems not to regularly eat seeds or plant material.Back to top
The female usually selects the nest site, choosing from several potential sites that the male offers. The nest is normally set in emergent vegetation, low trees, or shrubs over shallow water, sometimes on the ground or on small islands.
The nest is a flat platform made of whatever vegetation is present at the nest site. For ground nests, they start the platform by bending down stalks of rushes or reeds and then weaving them together. They then trim the platform with short stalks of plant material around the edges to create a cup. Some nests are less elaborate, little more than a pile of reeds. Nests built in trees over water are usually the most substantial, involving a base of sticks and more extensive mass of reeds or rushes. Nest dimensions vary tremendously; an average nest might be 15.4 inches across and 6.8 inches deep, with the interior cup 9 inches across by 2 inches deep.
|Clutch Size:||3-5 eggs|
|Number of Broods:||1 brood|
|Egg Length:||1.9-2.4 in (4.78-6.15 cm)|
|Egg Width:||1.3-1.5 in (3.32-3.88 cm)|
|Incubation Period:||17-21 days|
Pale bluish green to deep turquoise.
|Condition at Hatching:|
Helpless, with pink skin sparsely covered with brownish black down. Eyes partially closed until second day after hatching.
Pair formation and mating systems have not been well studied in White-faced Ibis. It appears that some arrive at the nesting colony already paired. At the nest site, male and female preen each other and present nesting material during nest-building, and both sexes have some role in gathering nest material and building the nest. Both defend the area immediately surrounding the nest, but combat is rare. Male and female share incubation and chick feeding duties, often traveling long distances to feeding areas while raising young. Foraging birds avoid deep water, but on rare occasions, they forage in water that covers their legs completely. Resting birds sometimes sunbathe to warm and dry themselves, raising the wings in an open position.Back to top
White-faced Ibises have been expanding their range in North America in recent decades, and their population size appears to have increased by an estimated 2.8% per year from 1968 to 2017, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 7.2 million with a U.S./Canada breeding population of 1.3 million. The species rates a 7 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Pollutants and toxic materials such as heavy metals, organochlorine and other pesticides, and selenium have been found in eggs and adults; in some cases, these materials have caused mortality or have reduced nesting success. Human disturbance at nesting colonies has caused abandonment, and the species is very sensitive to changes in both foraging and nesting areas. Diversion of water for irrigation and other uses has resulted in the abandonment of traditional colony sites in the United States.Back to top
Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.
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Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Ryder, R. A. and D. E. Manry (2020). White-faced Ibis (Plegadis chihi), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.whfibi.01
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