Scarlet Ibis

About the scarlet ibis

The scarlet ibis is a medium-sized wading bird found across tropical South America and part of the Caribbean, and it is unmistakable among the roughly 27 other extant ibis species thanks to its brilliant scarlet coloring. It is one of two national birds of Trinidad and Tobago, and its Tupi-Guarani name, guará, lends part of its name to several coastal municipalities in Brazil.

Carl Linnaeus first classified the species in 1758, and it has carried several scientific names over time before settling on Eudocimus ruber. Its taxonomic status remains debated: the scarlet ibis is extremely closely related to the American white ibis, sharing essentially identical bones, claws, beaks, and feather structure, differing mainly in pigmentation. Some researchers have documented significant crossbreeding where the two species' ranges overlap in Colombia and Venezuela, producing hybrids with pale orange or white-with-orange plumage, and have proposed treating the two as one species. Others note that the two color forms persist in the wild despite overlapping ranges, arguing they function as distinct species regardless of occasional hybridization. Hybridization is common in captivity; a notable case occurred in 1962, when scarlet ibis eggs placed in white ibis nests in Florida produced "pink ibises" still occasionally seen there today.

Adult plumage is almost entirely scarlet, described as "a vivid orange-red, almost luminous in quality," with only the tips of the longest wing feathers breaking the pattern in inky black or occasionally dark blue. The bill and feet are red, though the bill can darken toward blackish at the tip, and it is long, narrow, and curved downward. Juveniles look nothing like the adults, starting out a mix of grey, brown, and white; the scarlet coloring develops gradually over about two years as a heavy diet of red crustaceans takes effect, beginning on the back around the time the young bird starts to fly and spreading across the body as it intensifies. The scarlet ibis is the only wading bird in the world with red coloration. Adults measure 55–63 cm (22–25 in) long with a wingspan of about 54 cm (21 in); males, slightly larger than females, typically weigh around 1.4 kg (3.1 lb), and their bills run about 22% longer on average than females'.

Behavior and diet

The scarlet ibis is highly sociable, living in flocks of thirty or more and often congregating in colonies of several thousand birds for safety, alongside mixed flocks of storks, spoonbills, egrets, herons, and ducks during feeding and flight. Despite spending most of its time on foot or wading, it is a strong flier capable of long migratory distances, and flocks travel in a classic V formation.

Its long, thin, downcurved bill is built for probing soft mud and vegetation for food. Although the bird is popularly imagined to live mostly on shrimp, a study in the Llanos region found that much of its actual diet is made up of insects — chiefly scarab and ground beetles, with one species, Dyscinetus dubius, forming a large share of intake — along with water beetles and water bugs. It also eats plenty of shrimp and other red shellfish, plus ragworms, mollusks, small crabs, crayfish, frogs, small snakes, small fish, fruits, and seeds. The large amount of shrimp and other red-shelled prey supplies astaxanthin, the carotenoid pigment responsible for the bird's red coloring; in zoos, keepers often supplement the diet with beetroot and carrot to help maintain that color. In the Llanos, where seven ibis species share the same wetlands, scarlet ibises are the most aggressive of the group, sometimes stealing food from other species and following white-faced whistling ducks and livestock to catch insects the animals stir up.

Breeding pairs build simple nests described as "artless" loose platforms of sticks, typically roosting in young waterside mangrove trees and, where possible, nesting on islands to keep eggs and chicks safer from predators. Courtship includes preening, shaking, bill popping, head rubbing, and high flights; after mating, the female lays three to five eggs following a five-to-six-day gestation, and these incubate for 19–23 days. Pairs stay together and share parenting duties afterward. In southeastern Brazil, birds gather into colonies in mid-September, build nests by early November, and lay eggs in three synchronized waves running from early November into late January.

Range and habitat

Native flocks of scarlet ibis are found in Brazil, Colombia, French Guiana, Guyana, Suriname, and Venezuela, as well as on islands of the Netherlands Antilles and in Trinidad and Tobago, gathering in wetlands, mud flats, shoreline, and rainforest. Outlying colonies exist along the coasts of Espírito Santo, Rio de Janeiro, São Paulo, Paraná, and Santa Catarina in Brazil, with birds observed as far south as Joinville and the island of São Francisco do Sul in recent years.

The largest populations occur in the Llanos region spanning western Venezuela and eastern Colombia, a remote, fertile tropical grassland that offers a haven from human disturbance and supports dense concentrations of scarlet ibis alongside the related bare-faced ibis. Vagrant birds have turned up well outside this core range, in Belize, Ecuador, Panama, Aruba, Cuba, Dominica, Grenada, Jamaica, and even the United States; a natural presence on the U.S. Gulf Coast may date back to the 19th century, when John James Audubon recorded a few specimens in Louisiana, but virtually all modern North American sightings trace to introduced or escaped birds.

Conservation status

The scarlet ibis is listed as Least Concern (LC), with protected status recognized around the world. Global population totals remain relatively large, and the current rate of loss is not considered a threat to the species overall, even though several local populations are in decline. One specific concern is recent losses among established populations in French Guiana, and Brazil has placed the bird on its own national list of endangered species — a reminder that a healthy global listing can still coexist with real regional declines. An important protected habitat is Trinidad's Caroni Swamp, a 199-hectare (490-acre) wetland reserve set aside in 1953 specifically for the species.