Glossy Ibises forage in relatively open freshwater marshes but also frequent brackish and saltwater marshes, mudflats, mangrove swamps, wet agricultural fields, lake or pond edges, sewage treatment areas, and shallow rivers. Even pastures, plowed fields, and highway margins that have soil moist enough to permit probing for earthworms, grubs, and other invertebrates attract ibises. Less often, they forage in dry fields, where they eat insects or grain, such as rice. They nest in shrubs, trees, or marsh vegetation, sometimes far from foraging areas.Back to top
Glossy Ibises are able to forage both by sight and touch. When on dry land pursuing insects or eating grain, they pick and glean food items. They readily consume crops such as rice and sorghum. When in wetlands or wet soil, they use their long bills to probe into the substrate, or sometimes swing the bill, scythelike, through water or mud, feeling for prey. They eat a remarkable variety of creatures: leeches, earthworms, marine worms, dragonflies, crickets, grasshoppers, many species of beetles, soldierflies, crabs, shrimp, crayfish, mollusks, snails, fish, frogs, toads, newts, salamanders, snakes, and lizards. Flocks of Glossy Ibis forage quite close together, advancing slowly as they probe a muddy area. This activity often attracts Snowy Egrets and other species of waders, which capture minnows and other prey moving away from the feeding ibis flocks. In tidal areas, Glossy Ibis forage most heavily during a falling tide, as prey become increasingly accessible in shallows.Back to top
Together, both members of a pair build a large, bulky nest near a wetland. The male collects more of the material, which varies from reeds to sticks, depending on what vegetation is available near the nest site. The nest is sometimes on the ground in a reed bed but more often in bushes or short trees, up to about 12 feet above the ground.
The nest is a bulky platform of compacted sticks, twigs, or reeds. Pairs add to the nest even after eggs have been laid, sometimes fresh green leaves or grasses. Most nests are about a foot in diameter and vary in thickness from just a few inches to nearly a foot.
|Clutch Size:||3-4 eggs|
|Number of Broods:||1 brood|
|Egg Length:||1.9-2.3 in (4.7-5.8 cm)|
|Egg Width:||1.3-1.7 in (3.3-4.3 cm)|
|Incubation Period:||20-22 days|
|Nestling Period:||8-9 days|
Glossy Ibises are highly gregarious throughout their lives, feeding and resting in flocks and nesting in tight colonies where nests are usually no more than 2 feet apart. Pairs defend the immediate vicinity of their nest, attacking other ibises or herons that come too close, but otherwise are rarely aggressive. Courting Glossy Ibises bow to one another, preen each other (a behavior called allopreening), and touch their bills together, rattling them quickly while cooing—typically in the vicinity of the nest itself. Glossy Ibises fly in flocks that resemble those of cormorants, for which they can be mistaken at a distance. Ibises tend to glide more between bouts of flapping than cormorants do. Foraging birds avoid deep water, but on rare occasions they forage in belly-deep water and have even been observed swimming. Resting birds sometimes sunbathe to warm and dry themselves, raising the wings in an open position.Back to top
Glossy Ibises are found throughout the world. In North America, populations increased by an estimated 4.2% per year between 1966 and 2015 (indicating a cumulative increase of nearly eightfold over that period), according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 820,000 and gives the species a Continental Concern Score of 8 out of 20, indicating it is of low conservation concern. In 2002, the North American Waterbird Conservation Plan estimated 13,000–15,000 breeding Glossy Ibises in North America and listed it as a species of low concern. Oil spills, pesticides, wetland drainage, ditching of marshes for mosquito control, and human disturbance are causes of concern for this species.Back to top
Davis Jr., William E. and John C. Kricher. (2000). Glossy Ibis (Plegadis falcinellus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
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.
Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.
Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center (2014b). Available from http://www.mbr-pwrc.usgs.gov/bbs/.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.