Scarlet ibis

The scarlet ibis (''Eudocimus ruber'') is a species of ibis in the bird family Threskiornithidae. It inhabits tropical South America and part of the Caribbean. In form, it resembles most of the other twenty-seven extant species of ibis, but its remarkably brilliant scarlet coloration makes it unmistakable. It is one of the two national birds of Trinidad and Tobago, and its Tupi–Guarani name, guará, is part of the name of several municipalities along the coast of Brazil.

This medium-sized wader is a hardy, numerous, and prolific bird, and it has protected status around the world. Its IUCN status is Least Concern. The legitimacy of ''Eudocimus ruber'' as a biological classification, however, is in dispute. Traditional Linnaean taxonomy classifies it as a unique species, but some scientists have moved to reclassify it as a subspecies of a more general American ibis species, along with its close relative, the American white ibis (''Eudocimus albus'').

Taxonomy

The species was first classified by Carl Linnaeus in 1758. Initially given the binomial nomenclature of ''Scolopax rubra'' (the name incorporates the Latin adjective ''ruber'', "red"), the species was later designated ''Guara rubra'' and ultimately ''Eudocimus ruber''.

Biologically the scarlet ibis is very closely related to the American white ibis (''Eudocimus albus'') and is sometimes considered conspecific with it, leaving modern science divided over their taxonomy. The two birds each have exactly the same bones, claws, beaks, feather arrangements and other features – their one marked difference lies in their pigmentation. Traditional taxonomy has regarded the two as separate and distinct.

Early ornithological field research revealed no natural crossbreeding among the red and white, lending support to the two-species viewpoint. More recent observation, however, has documented significant crossbreeding and hybridization in the wild. 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 in Colombia and Venezuela. They observed individuals of the two species mating and pairing, as well as hybrid ibises with pale orange plumage, or white plumage with occasional orange feathers, and have proposed that these birds be classified as a single species. Hybridization has been known to occur frequently in captivity. However, the two color forms persist in the wild despite overlapping ranges and hybrid offspring having a distinctive color type, so according to the cohesion species concept they would be functionally different species.

Some biologists now wish to pair them with ''Eudocimus albus'' as two subspecies of the same American ibis. Others simply define both of them as one and the same species, with ''ruber'' being a color variation of ''albus''.

Description

Adult plumage is virtually all scarlet. The feathers may show various tints and shades, but only the tips of their wings deviate from their namesake color. A small but reliable marking, these wingtips are a rich inky black (or occasionally dark blue) and are found only on the longest primaries – otherwise the birds' coloration is "a vivid orange-red, almost luminous in quality." Scarlet ibises have red bills and feet however the bill is sometimes blackish, especially toward the end. They have a long, narrow, decurved bill. Their legs and neck are long and extended in flight.

A juvenile scarlet ibis is a mix of grey, brown, and white. As it grows, a heavy diet of red crustaceans produces the scarlet coloration. The color change begins with the juvenile's second moult, around the time it begins to fly: the change starts on the back and spreads gradually across the body while increasing in intensity over a period of about two years. The scarlet ibis is the only shorebird with red coloration in the world.

Adults are long, and the males, slightly larger than females, typically weigh about . Their bills are also on average around 22% longer than those of females. The life span of the scarlet ibis is approximately sixteen years in the wild and twenty years in captivity. An adult scarlet ibis has a wingspan of around . Though it spends most of its time on foot or wading through water, the bird is a very strong flyer: they are highly migratory and easily capable of long-distance flight. They move as flocks in a classic V formation.

Distribution and habitat

The range of the scarlet ibis is very large, and colonies are found throughout vast areas of South America and the Caribbean islands. Native flocks exist in Brazil; Colombia; French Guiana; Guyana; Suriname; and Venezuela, as well as the islands of the Netherlands Antilles, and Trinidad and Tobago. Flocks gather in wetlands and other marshy habitats, including mud flats, shoreline and rainforest. Outlying colonies have been identified in the coastal areas of the states of Espírito Santo, Rio de Janeiro, São Paulo (for example in the Santos-Cubatão mangroves of the Baixada Santista district), Paraná and Santa Catarina. In recent years, bird colonies can be seen as far south as in the coastal areas of Joinville and the island of São Francisco do Sul.

The highest concentrations are found in the Llanos region of western Venezuela and eastern Colombia. The fertile and remote tropical grassland plain of the Llanos provides a safe haven far from human encroachment. Together with its relative the bare-faced ibis, the scarlet ibis is remarkably prolific and conspicuous in the region.

Scarlet ibis vagrants have been identified in Belize, Ecuador, and Panama; Aruba, Cuba, Dominica, Grenada, and Jamaica; sightings have even been made in the United States. The species may well have been a natural vagrant to the Gulf Coast in the 19th century or earlier – in '' The Birds of America'', John James Audubon made brief remarks regarding three ''rubra'' specimens he encountered in Louisiana.Audubon