Tucano golabianca

Identificazione

Like other toucans, the white-throated toucan is brightly marked and has a huge bill. It has a total length of 50–61 cm (19.5–24 in). Body weight is somewhat variable, ranging in adult birds from 425 to 830 g (0.937 to 1.830 lb). The male averages slightly larger, at a mass of 642 g (1.415 lb), while the female averages 580 g (1.28 lb). However, the subspecies R. t. cuvieri is larger, with males averaging 702 g (1.548 lb) and females averaging 687 g (1.515 lb). Among standard measurements, the wing chord is 20.4 to 26.5 cm (8.0 to 10.4 in), the bill is 12.2 to 22 cm (4.8 to 8.7 in), the tail is 13.3 to 16.8 cm (5.2 to 6.6 in), and the tarsus is 4.5 to 5.6 cm (1.8 to 2.2 in). The only species of toucan that surpasses the white-throated in size is the toco toucan, however the R. t. cuvieri subspecies of white-throated toucan appears to perhaps be even heavier than the Toco species.<p>It has black plumage with a white throat and breast bordered below with a narrow red line. The rump is bright yellow and the crissum (the area around the cloaca) is red. The bare skin around the eye is blue. The bill has a yellow tip, upper ridge and base of the upper mandible, and the base of the lower mandible is blue. The rest of the bill is mainly black in R. t. cuvieri and mainly reddish-brown in R. t. tucanus, with intergrades showing a mixed coloration. Males are larger and longer-billed than females, but otherwise the sexes are alike.<p>Juveniles are noticeably shorter-billed, more sooty-black, and have duller plumage.<p>The white-throated toucan of the race cuvieri is virtually identical to the related channel-billed toucan of the race culminatus, but the latter is smaller and has a proportionally shorter bill with a more strongly keeled culmen. The call is often the best distinction between the species. White-throated has a yelping eeoo, hue hue, whereas channel-billed has a croaking song.

Tassonomia

The white-throated toucan was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae. He placed it with the other toucans in the genus Ramphastos and coined the binomial name Ramphastos tucanus. Linnaeus specified the "habitat" as South America. The type locality was restricted to Suriname by the American ornithologists Ludlow Griscom and James Greenway in 1937. The genus name is from Ancient Greek ῥαμφηστης/rhamphēstēs meaning "snouted" (from ῥαμφη/rhampē meaning "bill"). The specific epithet tucanus is from the Guarani language and may mean "bonenose".<p>Three subspecies are recognized by the International Ornithological Committee (IOC), the South American Classification Committee of the American Ornithological Society, and the Clements taxonomy:<p>BirdLife International's Handbook of the Birds of the World (HBW) treats the red-billed toucan as a species R. tucanus and the other two taxa as subspecies of "Cuvier's toucan" R. cuvieri. All three taxa were formerly considered to be three separate species. The red-billed toucan and Cuvier's toucan, which differ principally in the bill colour, interbreed freely wherever they meet and therefore now merit only subspecies status. Some authorities consider the Inca toucan to represent a stable hybrid population between the other two subspecies and do not recognize it as a separate subspecies.

Nome scientifico

Ramphastos tucanus

Autorità

Linnaeus, 1758

Ordine

Piciformi

Famiglia

Ramfastidi

Genere

Ramphastos

Areale e habitat

Migrazione

Resident species

Comportamento

Small flocks or more commonly pairs of birds move through the forest with a heavy, rather weak, undulating flight, rarely flying more than 100 m (330 ft) at a time. This species is primarily an arboreal fruit-eater, but will also take insects, lizards, eggs, and small birds.<p>The 2–4 white eggs are laid in an unlined cavity high in a decayed section of a living tree, or in an old woodpecker nest in a dead tree.<p>Both sexes incubate the eggs for at 14–15 days, and the toucan chicks remain in the nest after hatching. They are blind and naked at birth, with short bills, and have specialised pads on their heels to protect them from the rough floor of the nest. They are fed by both parents, and fledge after about 6 weeks. The parents continue feeding the juveniles for several weeks after they have left the nest.

Conservazione

Tendenza della popolazione

declining