The United States is home to two species of ibises, which are long-legged wading birds found in wetland habitats: White Ibis and Glossy Ibis.
Both species of ibises are important indicators of the health of wetland ecosystems in the US, as they rely on these habitats for feeding, nesting, and breeding. However, both species face threats from habitat loss and degradation, as wetlands continue to be drained and developed for human use.
The White Ibis is considered a species of Least Concern by the International Union for Conservation of Nature (IUCN), while the Glossy Ibis is considered a species of Least Concern in North America, but is listed as Vulnerable globally due to population declines in other parts of its range.
These two species are very similar and offer a nice identification challenge. There is a limited amount of range overlap but both species can wander far out of their typical range, and the ranges are changing. For example, 30 years ago reports of the Glossy Ibis in Texas were generally not accepted by the Texas Birds Committee of the Texas Ornithological Society. The Glossy Ibis is now so common in parts of Texas that sightings are no longer considered of special interest. Glossy Ibis do wander further west on occassion, west to western Texas.
Accurate identification generally requires a combination of field marks. Color of the eye and face, when seen well, are the best field marks.
Breeding / Summer Plumage
Comparison of adults in breeding plumage – generally March through August.
Grayish bill, color apparently varies. The Sibley guide indicates the bill is brownish. The National Geographic Guide shows a yellowish bill. This photograph and other Glossy’s we have seen have a grayish bill.
White outline around dark bill base, may not extend behind the eye.
Legs grayish to pale pink or red, often redder at the joints.
Note the red eye and red in front of the eye on this White-faced Ibis. This bird shows a hint of pink on an otherwise pale bill.
Note the white line around the eye of breeding-plumaged White-faced Ibis is not noticeable on this bird.
This bird might be a more difficult identification challenge.
The eye and the area just in front of the bill look like they may be turning red, indicative of the White-faced Ibis.
Note the legs look dark. The Sibley guide (first edition) shows dark legs on the juvenile and non-breeding White-faced Ibis as well as the Glossy Ibis.
On the other hand the National Geographic guide (Fifth Edition) shows pale legs on both species.
Ibis in Flight
Identifying distant or flying Glossy or White-faced Ibis may not be possible. Both of the following images are White-faced. The 2nd bird is fairly easy to identify in the photo, but it is a different situation when the bird is moving.
Sam is the founder of Birdzilla.com. He has been birding for over 30 years and has a world list of over 2000 species. He has served as treasurer of the Texas Ornithological Society, Sanctuary Chair of Dallas Audubon, Editor of the Cornell Lab of Ornithology's "All About Birds" web site and as a contributing editor for Birding Business magazine. Many of his photographs and videos can be found on the site.