Plegadis chihi
white-faced ibis

White-faced ibises are widespread, with two distinct ranges; one population is found in North and Middle America and a separate population is found in South America. Those found in North and Middle America cover most of the western and mid-western United States and most of Mexico. Breeding areas are as far north as southern Canada and as far east as Nebraska. Additionally they are found along the Gulf coast of Texas and Louisiana and in central Mexico. However, all except those found in California, Texas, Louisiana and central Mexico will migrate to southern parts of their range during the non-breeding season. Most of these winter in Mexico but other populations migrate to Guatemala, El Salvador and Honduras. South American population of white-faced ibises do not migrate for the winter. They are found from southern Brazil and southeastern Bolivia to northern Argentina. The eastern and western boundaries of their range are the Pacific and Atlantic Oceans. (BirdLife International 2004, 2006; Hancock, Kushlan, and Kahl, 1992; NatureServe, 2006; Ryder and Manry, 2005; Zaun et al., 2003)

White-faced ibises are found in both temperate and tropical regions. They tend to live in fresh and saltwater marshes containing many rushes and sedges which are used to nest on, for nesting materials, and for finding food. These birds are also found around ponds, rivers and in flooded pastures and agricultural fields. Rainy conditions are required for both foraging and nesting rainy conditions are required, limiting the areas in which they are found and influencing movement patterns. White-faced ibises are found from near sea level to 4300 m elevation in South America. (Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005)

White-faced ibises weigh between 450 and 525 grams and are 46 to 56 cm in length. Those found in South America tend to be smaller than those found in North America. When white-faced ibises first hatch they are bare on the underside and sparsely covered with brown or black down. After about two weeks they start to gain their juvenile plumage, which consists of the loss of down and gaining green and purple colored feathers. Juveniles are also noticeably smaller than adults. Adults are dark in color, either maroon or brown with dark green reflections on the underside. During mating season the head, neck, upper back, wing-coverts and underside becomes more chestnut in color. In both breeding and nonbreeding seasons there is a metallic green look to the flight feathers. These ibises get their name from the white coloring, which can be seen on their face and throat. Males have the same coloring as females but males are generally bigger than females. Parts of the face, as well as the legs and feet are red or purple because bare skin is exposed. The length of the bill varys between 15 and 18 cm, males have longer bills than females. There are no described sub-species. (Anonymous, 2003; Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005)

The longest known lifespan of this species in the wild is 14 years and 6 months. In captivity they have lived to 14 years. In a study done in Utah in 1967, 111 birds that had been tagged at birth were recovered, all of which died by the age of 9. (Ryder and Manry, 2005)

White-faced ibises are social and nomadic. If a foraging area becomes too dry they will leave in search of a more suitable location. White-faced ibises fly relatively long distances to find food. They fly at a rate of about 48 to 53 km per hour, they fly in a V formation with other birds for efficiency. Parents will shade their young while they are in the nest from the sun when it is hot out as the young tend to die quickly of heat exposure. These birds are gregarious, living in large groups. They are tolerant of other ibises outside of the breeding season. During the breeding season they will defend an area of about one meter around their nest, the average nest is two meters away from its neighbors. Sometimes landing and preening perches 3 meters away will also be defended. White-faced ibises forage in flocks, taking advantage of insects and other food items disturbed by conspecifics. (Anonymous, 2003; Attenborough, 1998; Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005)

Home Range

White-faced ibises defend small areas around nests during the breeding season. Outside of the breeding season, they forage over large areas in flocks. The size of these foraging areas has not been reported.

White-faced ibises communicate through sounds and visual displays. There are multiple different sounds that these birds make which have different meanings. There are separate sounds for calling to their young, when a mate is returning to the nest, and a sound used as a feeding call. (Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005)

White-faced ibises feed by probing the substrate with their long bill, in search of small animals. They feed in large groups of up to 1000 individuals. They feed mainly in moist areas around bodies of water and also in shallow (less than 20 cm) water. They are primarily carnivorous and feed on insects, crustaceans, spiders, snails, leeches, and amphibians. Snails and slugs are the large prey group by volume, accounting for 55 to 90% of all food eaten. Prey taken varies with the season, with more insects in the spring and summer than in other seasons. Males tend to eat more snails and slugs and females tend to eat more insects. (Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005; Soave et al., 2006)

The eggs, nestlings, and fledglings of white-faced ibises are taken by many different predators, including gull species (Larus), black-billed magpies (Pica pica), black-crowned night herons (Nycticorax nycticorax), common ravens (Corvus corax), raccoons (Procyon lotor), striped skunks (Mephitis mephitis), spotted skunks (Spilogale putorius), coyotes (Canis latrans), mink (Neovison vison), and long-tailed weasels (Mustela frenata). Mammals are more likely to become predators when water levels around nests fall, making access to the nest easier. Peregrine falcons (Falco peregrinus) and red-tailed hawks (Buteo jamaicensis) are able to prey on the adult white-faced ibises, but Ryder and Manny (2005) report that predation on adults is rare. Humans (Homo sapiens) are major predators of white-faced ibises, for food, feathers, and sport. Adults are vigilant in protecting their eggs and young from predators, helping to avoid predation. Their flocking habits also help in alerting flock members to potential danger. (Hancock, Kushlan, and Kahl, 1992; Ryder and Manry, 2005)

White-faced ibises aerate the soil with their foraging method of pushing their bill into the ground. They are important predators of many aquatic invertebrate groups, impacting their populations. Additionally, they are the hosts of several species of parasites: Ardeicola rhaphidius, Ciconiphilus blagoweschenskii, Colpocephalum leptopygos, Ibidoecus bisignatus, and Plegadiphilus plegadis. (Ryder and Manry, 2005)

White-faced ibises sometimes have an economic impact on farmers because they can trample crops in wet fields during foraging. Crayfish farmers experiences losses when white-faced ibises visit their operations. (Ryder and Manry, 2005)

Ibises are hunted for food in some areas. They are also important for birding ecotourism and are essential components of the healthy, wetland habitats in which they live. (Hancock, Kushlan, and Kahl, 1992)

White-faced ibises have a large geographic range and populations remain large. Population trends haven't been quantified, but populations are believed to be stable currently.