| Scarlet ibis | |
|---|---|
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| A scarlet ibis atL'Oceanogràfic | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Pelecaniformes |
| Family: | Threskiornithidae |
| Genus: | Eudocimus |
| Species: | E. ruber |
| Binomial name | |
| Eudocimus ruber | |
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| Synonyms | |
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Thescarlet ibis, sometimes calledred ibis (Eudocimus ruber), is aspecies ofibis in the bird familyThreskiornithidae. It inhabits tropicalSouth America and part of theCaribbean. In form, it resembles most of the other twenty-seven extant species of ibis, but its remarkably brilliantscarletcoloration makes it unmistakable. It is one of the two national birds ofTrinidad and Tobago, and itsTupi–Guarani name,guará, is part of the name of severalmunicipalities along the coast ofBrazil.[3]
This medium-sizedwader is a hardy, numerous, and prolific bird, and it has protected status around the world. ItsIUCN status isLeast Concern. The legitimacy ofEudocimus ruber as abiological classification, however, is in dispute. TraditionalLinnaean taxonomy classifies it as a unique species, but some scientists have moved to reclassify it as asubspecies of a more general American ibis species, along with its close relative, theAmerican white ibis (Eudocimus albus).
The species was first classified byCarl Linnaeus in 1758. Initially given thebinomial nomenclature ofScolopax rubra[4] (the name incorporates theLatin adjectiveruber, "red"), the species was later designatedGuara rubra and ultimatelyEudocimus ruber.[5]
Biologically the scarlet ibis is very closely related to theAmerican white ibis (Eudocimus albus) and is sometimes consideredconspecific with it,[4][6] leaving modern science divided over theirtaxonomy. The two birds each have exactly the same bones, claws, beaks, feather arrangements and other features – their one marked difference lies in their pigmentation.[7] Traditional taxonomy has regarded the two as separate and distinct.[7]
Early ornithological field research revealed no natural crossbreeding among the red and white, lending support to the two-species viewpoint.[7] More recent observation, however, has documented significant crossbreeding andhybridization 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 theLlanos 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 orangefeathers, and have proposed that these birds be classified as a single species.[4] 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 thecohesion species concept they would be functionally different species.[8]
Some biologists now wish to pair them withEudocimus albus as twosubspecies of the same American ibis.[4] Others simply define both of them as one and the same species, withruber being a color variation ofalbus.[9]
Adultplumage is virtually allscarlet. The feathers may show varioustints 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 longestprimaries[10] – otherwise the birds' coloration is "a vivid orange-red, almost luminous in quality."[11] Scarlet ibises have red bills and feet; however, the bill is sometimes blackish, especially toward the end.[12] They have a long, narrow, decurved bill. Their legs and neck are long and extended in flight.[13]
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.[14] The color change begins with the juvenile's secondmoult, 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.[10] The scarlet ibis is the onlyshorebird with red coloration in the world.
Adults are 55–63 centimetres (22–25 in) long,[15] and the males, slightly larger than females, typically weigh about 1.4 kilograms (3.1 lb).[10] Their bills are also on average around 22% longer than those of females.[16] The life span of the scarlet ibis is approximately sixteen years in the wild and twenty years in captivity.[17] An adult scarlet ibis has a wingspan of around 54 centimetres (21 in).[10] Though it spends most of its time on foot or wading through water, the bird is a very strong flyer:[14] they are highlymigratory and easily capable of long-distanceflight. They move asflocks in a classicV formation.[10]
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 inBrazil;Colombia;French Guiana;Guyana;Suriname; andVenezuela, as well as the islands of theNetherlands Antilles, andTrinidad and Tobago.[1] Flocks gather inwetlands and other marshy habitats, including mud flats, shoreline andrainforest.[10] Outlying colonies have been identified in the coastal areas of the states ofEspírito Santo,Rio de Janeiro,São Paulo (for example in the Santos-Cubatão mangroves of theBaixada Santista district),Paraná andSanta Catarina.[18] In recent years, bird colonies can be seen as far south as in the coastal areas ofJoinville and the island ofSão Francisco do Sul.[19][20]
The highest concentrations are found in theLlanos region of western Venezuela and eastern Colombia. The fertile and remotetropical grasslandplain of the Llanos provides a safe haven far from human encroachment.[11] Together with its relative thebare-faced ibis, the scarlet ibis is remarkably prolific and conspicuous in the region.[21]
Scarlet ibisvagrants have been identified in Belize, Ecuador, and Panama; Aruba, Cuba, Dominica, Grenada, and Jamaica; sightings have even been made in the United States.[1] The species may well have been a natural vagrant to theGulf Coast in the 19th century or earlier – inThe Birds of America,John James Audubon made brief remarks regarding threerubra specimens he encountered in Louisiana.[22] However, virtually all modern occurrences of the species in North America have been introduced or escaped birds. In one notable example from 1962, scarlet ibis eggs were placed in white ibis nests in Florida'sGreynolds Park, and the resulting population hybridised easily, producing "pink ibises" that are still occasionally seen.[15][23]
Mating pairs buildnests in a simple style, typically "loose platforms of sticks"[14] of a quality described as "artless".[24] They roost in leaf canopies, mostly preferring the convenient shelter of young watersidemangrove trees.[25] Scarlet ibises like wet, muddy areas such as swamps, but for safety they build their nests in trees well above the water. If they can, they nest on islands, where their eggs and chicks are less likely to be in danger from predators.[26]
To attract a female, the male 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 thecloacal openings.[27] After a gestation period of five to six days,[10] the female lays a clutch of three to five smooth, matteeggs which typically incubate for 19–23 days.[17][28] After a successful courtship, pairs remain faithful and cohabitant, sharing parental responsibilities for the young.[10]
In southeastern Brazil, the ibises gather incolonies 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.[18]
Their distinctive long, thinbills are used to probe for food in soft mud or under plants.[11] Popularly imagined to be eating onlyshrimp, a recent study in theLlanos has found that much of their diet consists of insects, of which the majority werescarabs andground beetles.[29] One species in particular, a scarab beetleDyscinetusdubius, formed a large part of the diet.[29] Other insect prey includewater beetles andwater bugs.[10] In contrast, the diet of the co-occurring American white ibis there differed, the latter consuming morebugs, fish and crustaceans.[29]
They do, however, eat much shrimp and other similar fare like ragworms (Nereis), mollusks (such asMelampus), small crabs (Aratus,Uca andUcides) and other crustaceans, such as crayfish.[10][14][17][31] The large quantity of shrimp and other red shellfish produces a surfeit ofastaxanthin, acarotenoid which is the key component of the birds' red pigmentation.[14][32] Frogs, small snakes, small fish (Cichlidae), fruits and seeds are also occasional prey items for scarlet ibises.[10][17][33] When kept in zoos, the birds' diet often contains beetroot and carrot supplement to maintain color vibrancy in their plumage.[14]
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 trailingwhite-faced whistling ducks (Dendrocygna viduata) and domestic livestock, and catching insects disturbed by them.[34]
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 proximity to other pairs in the same tree.[10]
For protection, flocks often congregate in large colonies of several thousand individuals.[10] They also regularly participate in mixed flocks, gaining additional safety through numbers: storks, spoonbills, egrets, herons and ducks are all common companions during feedings and flights.[10]
The species has protected status throughout the world,[14] and theInternational Union for Conservation of Nature has classified the scarlet ibis as a species ofLeast Concern on theIUCN Red List.[1] 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.[1] Nonetheless, recent losses by established populations in French Guiana have become a concern for conservationists, and in Brazil the bird has been included on a national list ofendangered species.[35]
The scarlet ibis and the rufous-vented chachalaca, popularly known as thecocrico, are thenational birds ofTrinidad and Tobago respectively.[36] Both birds are featured on thecoat of arms of Trinidad and Tobago.[36][37] The cocrico is found on Tobago, Venezuela and Colombia.[36] The scarlet ibis is associated with Trinidad; there are not documented records of the scarlet ibis on Tobago for the last fifteen years.[38]
An important local habitat for the scarlet ibis is the wildlife sanctuary ofCaroni Swamp of Trinidad, a 199 hectares (490 acres) wetland reserve first designated in 1953 specifically to provide a habitat for the scarlet ibis.[39]
Using the bird as a literary symbol, American author James Hurst composed a popular short story, "The Scarlet Ibis" (1960).[11] A more recent short story, "Scarlet Ibis" byMargaret Atwood, is included inBluebeard's Egg (1983).[40] The name also belongs to a book of verse by American poetSusan Hahn.[41]
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The scarlet ibis builds its artless nest of brush in inaccessible places on low trees.
Data related toEudocimus ruber at Wikispecies
