New York Natural Heritage Program
Glossy Ibis
Plegadis falcinellus (Linnaeus, 1766)
Birds

Identifying Characteristics [-]
The Glossy Ibis is a small to medium-sized bird 45-65 cm in length with a wingspan averaging 90 cm (Peterson 1980; National Geographic Society 1999). They are easily identified by their long brownish grey bill that curves downward. From a distance the birds appear black in color. Adults in breeding plumage are rich brown-red in color, the back, wings, and tail are bronzy with some glossy purple and green. The bare skin around the bill and eye changes from grey to dark blue-black with a pale whitish-blue edge running along the top and bottom of the eye. The iris is brown. The legs are gray-green and during breeding season, the joints turn red. Nonbreeding adult plumage is similar to breeding plumage but the colors are duller. Males and females are similar in color but females are smaller. Juveniles are lighter and duller in color than adults and have some white streaking on their face, head, throat, and foreneck. Hatchlings are semialtricial and have sparse down that is mostly black with some white on the throat and white-orange on the head. The bill is pink and has black bands at the base, middle, and tip. The legs are yellow and feet are pink. Eggs are elliptical to ovate in shape, averaging 50 mm by 40 mm in size. The surface of the egg is smooth or finely pitted and deep greenish blue in color. Nests are a platform of twigs lined with leaves and are about 35 cm across and 5 to 10 cm deep. The Glossy Ibis has very few vocalizations and is mostly silent. The begging call of chicks sounds like a buzzing. Adults emit a low krunk krunk sound and chatter and grunt when in flocks (Baynard 1913; Bent 1962; Davis and Kritcher 2000).

Characters Most Useful for Identification [-]
The brownish down curved bill, brown iris, olive colored legs, and incomplete white margin around the bare parts of the face of the adults during breeding season make the Glossy Ibis distinguishable from other Ibis species (Peterson 1980; National Geographic Society 1999).

Best Life Stage for Proper Identification [-]
Glossy Ibis can be easily identified when the adults are in their breeding plumage.

Behavior [-]
Glossy Ibis are colonial nesters. They arrive at their breeding grounds in the spring and establish pair bonds shortly after. Both male and female assist in nest construction, with the male doing most of the building. Eggs are laid down shortly after the nest is built with one egg being laid per day until the clutch is complete (3-5 eggs). The incubation period lasts on average 20 days with both parents taking turns. Hatching is asynchronous and occasionally results in mortality of younger chicks (Baynard 1913). In New York, egg dates are between May and July with chicks fledging beginning in July and continuing to September. (Bull 1974). Glossy Ibis will renest if unsuccessful and will also use abandoned nests of other wading birds (Baynard 1913).

Diet [-]
Glossy Ibis feed on a variety of invertebrates including crayfish, dragonfly larvae, caddisflies, worms, grasshoppers, small mussels and clams, and occasionally grains. They forage in same-species groups or among other wading birds and probe the shallow waters and mudflats with their bill in search of pray (Baynard 1913; Bent 1926; Erwin 1983; Davis and Kritcher 2000).
Glossy Ibis Images
click to enlarge
The Best Time to See
In New York, Glossy Ibis begin to arrive during the spring (April-May) and remain throughout the breeding season (Post 1962). They begin their fall migration to their wintering grounds in mid-August-October (Davis and Kritcher 2000).
J F M A M J J A S O N D
Present Breeding
The time of year you would expect to find Glossy Ibis present (blue shading) and breeding (orange shading) in New York.
Similar Species
  • White Ibis (Eudocimus albus)
    The White-faced Ibis has a red iris, reddish bill, and red legs. They have a white margin of feathers around the bare skin on the face extending around the eye and down the chin. The breeding plumage in the White Ibis is more bronze than in the Glossy Ibis (National Geographic Society 1999).