Montana Field Guide

White-faced Ibis - Plegadis chihi

The White-faced Ibis is a medium-sized wading bird with dark maroon or brown plumage, a long neck and legs, and a long, decurved bill. Males are almost always larger than females and adults are larger than juveniles for the first 6 to 9 months (Ryder and Manry 1994). The adult body length ranges from 46 to 56 cm (18.1 to 22.0 inches) with wingspans ranging from 94 to 99 cm (37 to 39 inches). Weight varies ranging from 450 to 525 grams (1.0 to 1.2 lb.) and the bill length averages between 15 to 18 cm (6 to 7 inches) (Ryder and Manry 1994). Male and female plumages cannot be distinguished. In the adult breeding plumage, the head, neck, upper back, wing coverts, and undersides are a dark maroon or brown with a metallic green and bronze sheen. The head of the White-faced Ibis has bare facial skin that is reddish or purple. White feathers on the head separate the forehead from the face and also encircle the eye. The eye itself is red (Ryder and Manry 1994). The bill is cream with some shades of red (Pratt 1976) and the legs are bright red. The non-breeding plumage is similar to the breeding plumage without the presence of the white face feathers. Also, the overall plumage is less glossy (Oberholser 1974), and the bill and legs become an olive-gray color (Pratt 1976).

The juvenile plumage has a fuscous foreneck and anterior surface. The back, tail and wings are a dull metallic, greenish-olive and often appears oily (Palmer 1962, Oberholser 1974). When observing immature White-faced Ibises, it can be extremely difficult to separate from the closely related Glossy Ibis. White-faced Ibises have a limited vocalization array. Single birds, pairs, and flocks often give an "oink oink" or "ka-onk ka-onk" sound (Oberholser 1974). During nest building, they often give a guttural babbling sound. Vocalizations during interspecific aggression are long "gheeeeeee" sounds and the greeting call by the male to the female is a "geeeeek, geeeeek, geeeeek" sound (Belknap 1957). White-faced Ibis eggs are elliptically-ovate to round shaped and range in color from a pale bluish-green to a deep turquoise, with no markings (Bent 1926, Belknap 1957, Kotter 1970, King et al. 1980). Dimensions average 51.2 to 52.26 mm by 36.0 to 37.0 mm (Bee 1933 in Kaneko 1972, Belknap 1957), and weights average 28.4 to 43.7 grams (Kotter 1970). White-faced Ibises are a single brood species, but will attempt to renest after an early nest failure.

The White-faced Ibis is very similar in appearance to the closely related Glossy Ibis and identification can be difficult. Distinguishing characteristics which separate the two species include the red iris versus a more brownish or dark iris, bright red legs versus more grayish ones, the bare facial skin colored red and trim of white feathers which surround the eye versus a darker face with only small white lines connecting the bill to the eye (Ryder and Manry 1994), and the olive-gray bill versus a more brown colored bill (Sibley 2000).

Montana Range

White-faced Ibises usually leave their wintering grounds in late March to early April. The earliest White-faced Ibis observation in Montana was at Lee Metcalf National Wildlife Refuge in March, but the most concentrated arrival in Montana occurs in May (Montana Bird Distribution 2002). In late summer, White-faced Ibises will disperse throughout the state before beginning the fall migration to their wintering habitat (Ryder and Manry 1994). In Montana, most begin their southern movement in August and by September they are usually gone from the state (Montana Bird Distribution 2002). On April, 5th, 1964 at least one White-faced Ibis was observed in the Three Forks area (Skaar 1969) and in 1967, two individuals were observed at Benton Lake National Wildlife Refuge until October 6th (Benton Lake NWR 1988).

The White-faced Ibis breeding habitat is typically freshwater wetlands, including ponds, swamps and marshes with pockets of emergent vegetation. They also use flooded hay meadows and agricultural fields as feeding locations. Ibises nest in areas where water surrounds emergent vegetation, bushes, shrubs, or low trees. In Montana, White-faced Ibises usually use old stems in cattails (Typha spp.), hardstem bulrush (Scirpus acutus) or alkali bulrush (S. paludosus) over shallow water as their nesting habitat (DuBois 1989). Water conditions usually determine whether nesting occurs in a particular area. Therefore, White-faced Ibis nesting sites can often move around from year to year. However, they are a fairly adaptable species and the primary breeding requirement is colony and roosting site isolation. During migration, White-faced Ibises use more varied habitats for resting and feeding sites, ranging from wooded streams, mudflats, and grassy fields to small marshes and sewage ponds (Duebbert 1968, Locatelli and Blankenship 1973, Ducey 1988, Baumgartner and Baumgartner 1992).

No information regarding food habits exists for White-faced Ibises in Montana. However, in other areas of the species' range, they typically feed in freshwater marshes on crayfishes, frogs, fishes, insects, newts, earthworms, crustaceans, etc. (Terres 1980). In the Central Valley of California, they preferentially selected foraging sites with significantly higher midge (Chironomidae) and significantly lower Oligochaete biomass (Safran et al. 2000). White-faced Ibises can fly 5 to 25 miles between the nesting or roosting and foraging sites (Trost 1989).

No information is available for White-faced Ibis ecology in Montana. Ecological sources from other ibis habitat locations state that nesting colonies are often shared with Black-crowned Night-herons and Franklin's Gulls, both of which may prey on ibis chicks or eggs (Trost 1989). Although gregarious, and may travel in flocks of up to 300 individuals, White-faced Ibis generally flock in smaller numbers.

Only recently has the White-faced Ibis reproduced in Montana. Prior to 1970, no breeding records existed for the state. Even into the early 1980's only a few scattered breeding instances were observed. Since the mid-1980's, White-faced Ibis numbers in known colonies have increased and new colonies have been located (DuBois 1989). Two theories exist to explain this apparent recent range expansion into Montana. The first describes the very transient behavior of the species. White-faced Ibises are extremely dependent on appropriate wetland habitat and water level consistency. When wetlands in the Great Basin and in particular the Great Salt Lake rose to record levels in the early 1980's, large ibis colonies were flooded. This flooding closely coincided with the marked population increases in Montana, presumably due to the northern movement of Great Basin/Utah birds. The other theory regarding White-faced Ibis presence in Montana states simply that they have always been here and have been overlooked (DuBois 1989). Regardless of the reason, the White-faced Ibis does breed at several locations in Montana, with colonies usually about 50 pairs or less. However, due to the few locations and only recent presence, no information regarding White-faced Ibis reproduction exists for the state.

In other areas of the species' range, where reproductive studies have been conducted, information includes clutch sizes ranging from typically 3 to 4 (range of 2 to 7) (Trost 1989). The incubation period is 21 to 22 days, and normally only two young survive to fledging (Trost 1989). The young are semi-altricial and fledge after 28 days; birds do not breed until they are 2 years old (Trost 1989, Ryder and Manry 1994). Nests are typically spaced 0.5 to 10 m apart, with density often increasing toward the center of the colony (summarized in Ryder and Manry 1994). Nest structures are highly variable, and are typically composed of the dominant vegetation in the colony; outside diameter may range from 27 to 50 cm, and nests are 10 to 25 cm deep (summarized in Ryder and Manry 1994). Nests may be woven into emergent vegetation, be made on a platform or bent over adjacent vegetation or may be placed on a more solid platform or on the ground (Ryder and Manry 1994).

Although no management activities are in place specifically for White-faced Ibises in Montana, water level manipulation in nesting areas for other species is ongoing. Because all White-faced Ibises in Montana currently breed in colonies located within water units managed for waterfowl, active management of water level can and does impact the breeding ibises in the management area. Conscious management of water levels for waterfowl to include White-faced Ibises would maintain or enhance nesting habitat for this species. White-faced Ibises are a Species of Management Concern in Region 6 (U.S. Fish and Wildlife Service 1995).