[2] This particular ibis species is a medium-sized wading bird, possessing an overall white plumage with black wing-tips (usually only visible in flight), and having the typical downward-curving bill of the ibises, though of a bright red-orange color, the same hue as its long legs.

Pairs are predominantly monogamous and both parents care for the young, although males tend to engage in extra-pair copulation with other females to increase their reproductive success.

Human pollution has affected the behavior of the American white ibis via an increase in the concentrations of methylmercury, which is released into the environment from untreated waste.

Exposure to methylmercury alters the hormone levels of American white ibis, affecting their mating and nesting behavior and leading to lower reproduction rates.

The American white ibis was one of the many bird species originally described by Carl Linnaeus in the 1758 10th edition of his Systema Naturae, where it was given the binomial name of Scolopax albus.

[8] However, in a field study published in 1987, researchers Cristina Ramo and Benjamin Busto found evidence of interbreeding in a population where the ranges of the scarlet and white ibises overlap along the coast and in the Llanos region of Colombia and Venezuela.

[8] Ornithologists James Hancock and Jim Kushlan also consider the two to be a single species, with the differences in plumage, size, skin coloration and degree of bill darkening during breeding season forming the diagnostic characters.

They have proposed the populations recontacted in northwestern South America after a period of separation, and that the color difference is likely due to the presence of an enzyme that allows uptake of pigment in the diet.

They have questioned whether white-plumaged birds of South America are in fact part of the ruber rather than the albus taxon, and acknowledge that more investigation is needed to determine this.

[8] The newly hatched American white ibis is covered with violet down feathers, deepening to dark brown or black on the head and wings.

[2] Laguna Cuyutlán is an isolated and regionally important wetland in the state of Colima on México's west coast where a breeding colony has been recorded.

[27] The population of American white ibises in a colony at Pumpkinseed Island in Georgetown County, South Carolina, dropped from 10,000 to zero between 1989 and 1990 as Hurricane Hugo had inundated nearby freshwater foraging areas with salt water.

[29] The American white ibis is found in a variety of habitats, although shallow coastal marshes, wetlands and mangrove swamps are preferred.

[33] Much of the time roosting is spent preening, biting and working their feathers with their long bills, as well as rubbing the oil glands on the sides of their heads on back plumage.

[34] In the 2006 breeding season, a non-breeding adult female was observed to be tending to multiple nests that belonged to other American white ibises—the first time the behavior has been documented for this species.

[37] The success rate of parents raising one or more young to 20 days of age ranges widely from 5 to 70% of nests, and varies greatly between nearby colonies.

[28] American white ibis parents have been known to supplement their chicks' diet with items such as cockroaches and rotting food from human garbage in poorer years, when fish and crayfish are more scarce.

[40] The draining of wetlands in south Florida has also impacted on species that forage in shallow water such as the American white ibis, and its increase in numbers is a key indicator of restoration of habitat within the Everglades.

[28] During periods of food limitations and starvation events, the American white ibis tends to exhibit sex-dependent pre-fledgling mortality.

[22] The fish crow (Corvus ossifragus) is common raider of American white ibis nests, accounting for up to 44% of egg loss in a field study at Battery Island, North Carolina.

[30] In the breeding season, American white ibises in a colony at Pumpkinseed Island travelled further to forage in freshwater wetlands and catch crayfish, than nearby saltwater areas where fiddler crabs predominated, indicating their benefit was worth the extra energy expended in fetching them for their young.

[47] The willet (Tringa semipalmata) has been observed trailing American white ibis and catching prey disturbed by them, and even kleptoparasitizing (stealing) from them, in J. N. "Ding" Darling National Wildlife Refuge on Sanibel Island in Florida.

[52] During the summer, the American white ibis roams along the coast of tidal flats and mangrove swamps as the inland marshes are usually flooded.

[30] It has become more common in urban landscapes in Florida since the late 1990s,[53] and is one of a number of wetland-dependent bird species which forages in man-made ponds on golf courses in the southwest of the state.

[59] The explanation of the species' sexual dimorphism of body size is unclear, because no differences between the sexes in feeding success rates or the foraging behavior have been observed and, as males are larger, they need more food than females.

[61] A total of 51 species of parasitic worm have been recovered from the American white ibis, predominantly from the gastrointestinal system and particularly the small intestine.

In the Everglades ecosystem, human pollution has led to increased concentrations of methylmercury, which have impacted the behaviors of the American white ibis.

[68] Hormone levels in males are affected, leading to a decrease in the rates of key courtship behavior, and fewer approaches by females during the mating season.

Both the chemically induced "homosexual" behavior and the diminished ability to attract females by males have reduced reproduction rates in affected populations.

[69] Exposure of American white ibises to methylmercury causes reduced foraging efficiency[70] and it also makes them more likely to abandon nests owing to the disruptive effect of the pollutant on the bird's hormone systems, which in turn affects parental care behavior.