The scarlet ibis (Eudocimus ruber) is a species of ibis in the bird family Threskiornithidae. It inhabits tropical South America and islands 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.
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 an increasing number of scientists have moved to reclassify it as a subspecies of a more general American ibis species, along with its close relative Eudocimus albus.
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 55–63 centimetres (22–25 in) long, and the males, slightly larger than females, typically weigh about 1.4 kilograms (3.1 lb). 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 54 centimetres (21 in). 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.