Scarlet Ibis

Appearance

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 and are found only on the longest primaries – otherwise the birds' coloration is "a vivid orange-red, almost luminous in quality."

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 long, and the males, slightly larger than females, typically weigh about 1.4 kilograms. 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. 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

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 Argentina; Brazil; Colombia; French Guiana; Guyana; Suriname; and Venezuela, as well as the islands of the Netherlands Antilles, and Trinidad and Tobago.

Status

The species enjoys protected status throughout the world, and the International Union for Conservation of Nature has classified the Scarlet Ibis as a species of Least Concern on the IUCN Red List. Though several local populations appear to be in decline, global totals remain relatively large and the current rate of losses is not considered a threat to the species' survival. Nonetheless, recent losses by established populations in French Guiana and the Florida Everglades have become a concern for conservationists, and in Brazil the bird has been included on a national list of endangered species.

Behavior

The Scarlet Ibis is a sociable and gregarious bird, and very communally-minded regarding the search for food and the protection of the young. They live in flocks of thirty or more. Members stay close, and mating pairs arrange their nests in close proximity to other pairs in the same tree.

For protection, flocks often congregate in large colonies of several thousand individuals. They also regularly share time among other avian creatures, gaining additional safety through numbers: storks, spoonbills, egrets, herons and ducks are all common companions during feedings and flights.

Habitat

Flocks gather in wetlands and other marshy habitats, including mud flats, shoreline and rainforest. There is an outlying colony in the Santos-Cubatão mangroves of Baixada Santista district in southeastern Brazil, which is considered critically endangered.

Reproduction

Mating pairs build nests in a simple style, typically "loose platforms of sticks" of a quality sometimes described as "artless." They roost in leaf canopies, mostly preferring the convenient shelter of young waterside mangrove trees.

To attract a female, the males will perform a variety of mating rituals such as "preening, shaking, bill popping, head rubbing, and high flights." As with most birds, mating does not involve any coupling or insertion: instead, a transfer of seminal fluids occurs during external contact between the cloacal openings. After a gestation period of five to six days, the female lays a clutch of three to five smooth, matte eggs which typically incubate for 19–23 days. After a successful courtship, pairs remain faithful and cohabitant, sharing parental responsibilities for the young.

In southeastern Brazil, the ibis gather in colonies in mid-September and build nests at the beginning of November. Egg laying within the colony was synchronous, with female birds laying eggs in three waves in early November, late December and late January.

Food

Their distinctive long, thin bills are used to probe for food in soft mud or under plants. Popularly imagined to be eating only shrimp, a recent study in Llanos has found that much of their diet consists of insects, of which the majority were scarabs and ground beetles . One species in particular, a scarab beetle ''Dyscinetus dubius'', formed a large part of the diet. In contrast, the diet of the co-occurring American White Ibis there differed, the latter consuming more bugs, fish and crustaceans.

They do, however, eat much shrimp and other similar fare like small crabs, mollusks and other crustaceans. The large quantity of shrimp and other red shellfish produces a surfeit of astaxanthin, a carotenoid which is the key component of the birds' red pigmentation. When kept in zoos, the birds' diet is often supplemented by beetroots and carrots to maintain color vibrance in their plumage.

The Llanos are notable in that these wetland plains support seven species of ibis in the one region. Here, Scarlet Ibis are the most aggressive, and attack other species to steal their food. They have also been observed trailing White-faced Whistling Duck and domestic livestock, and catching insects disturbed by them.