Toco toucan
The toco toucan is a species of bird in the toucan family Ramphastidae. It is the largest species of toucan and has a distinctive appearance, with a black body, a white throat, chest and uppertail-coverts, and red undertail-coverts. Its most conspicuous feature is its huge beak, which is yellow-orange with a black base and large spot on the tip. It is endemic to South America, where it has a wide distribution from the Guianas south to northern Argentina and Uruguay, and its range has recently been expanding southwards. Unlike other toucans, which inhabit continuous forests, toco toucans inhabit a variety of semi-open habitats at altitudes of up to. They are especially common in the Brazilian cerrado, gallery forests, and the wetlands of the Pantanal.
Toco toucans mainly feed on fleshy fruits, but also supplement their diets with insects, eggs, and the nestlings of other birds. They will eat any available sugar-rich fruits, and show a high level of variation in their diet depending on the surrounding habitat. Breeding is seasonal, with the timing of the breeding season differing between regions. Nests are usually made in hollows in trees and contain two to four eggs; both parents incubate the eggs for 17–18 days before hatching. It is considered to be of Least Concern by BirdLife International.
Taxonomy
The oldest known remains of the toco toucan date back to around 20,000 years ago, from Pleistocene deposits in Lagoa Santa, Minas Gerais. The first European account of the species was written by the French naturalist Pierre Belon in his 1555 work Histoire de la nature des oyseaux. Belon possessed only a specimen of the bird's bill, and hypothesized that the toucan was a web-footed, fish-eating bird due to its long, serrated bill, which Belon thought shared some features with the bills of pelicans, mergansers, and some ducks. Belon's description and ideas remained influential until the eighteenth century.The species was formally described as Ramphastos Toco by the German zoologist Philipp Ludwig Statius Müller in 1776 on the basis of specimens from Cayenne, French Guiana. In 1862, the German ornithologist Jean Cabanis described R. albogularis as a new species based on specimens from southern Brazil; by 1870, it had been demoted to the status of a subspecies of R. toco. The name of the genus, Ramphastos, derives from a misspelling of the Ancient Greek ῥαμφηστης, rhamphēstēs, meaning snouted, which is itself derived from the Greek ῥαμφη, rhampē, meaning bill; the name refers to the large bill of the toucans. The specific name toco comes from either Tucá or Tucán, the Guarani word for toucan, and may mean "bone-nose". Toco toucan is the official common name designated by the International Ornithologists' Union. It is called the tucanuçu in Portuguese, tucán grande or tucán toco in Spanish, and tucano-boi locally in Rio Grande do Sul, Brazil. In Tsimané, an indigenous language spoken in the Bolivian Amazon, it is known as yubibi.
The toco toucan is one of eight species currently placed in the genus Ramphastos, and one of over forty species in the toucan family Ramphastidae. In 1974, the German ornithologist Jürgen Haffer hypothesized that the Ramphastos toucans could be split into two clades : the "smooth-billed yelpers", comprising the chestnut-mandibled and yellow-throated toucans, and the "channel-keel-billed croakers", comprising the toco, red-breasted, keel-billed, Choco, and channel-billed toucans. He further postulated that the toco toucan was basal within the group of channel-keel-billed croakers. Later studies of mitochondrial DNA have largely confirmed the existence of these two clades, but have found the toco toucan to be basal within the family instead of being a part of the channel-keel-billed croakers. The following cladogram shows phylogenetic relationships within Ramphastos, based on a 2009 study by José Patané and colleagues:
Subspecies
Two subspecies are recognized by the IOU:- R. t. toco Statius Müller, 1776: found in the Guianas, north and northeastern Brazil, and south-eastern Peru.
- R. t. albogularis Cabanis, 1862: Found in Paraguay, southern and eastern Brazil, northern Bolivia, and northern Argentina. Very similar to the nominate subspecies, but is said to be slightly smaller, with a shorter bill and whiter throat; however, measurements of individuals from both subspecies have found that differences in size are not consistent.
Description
The extremely long and thin bill is usually reddest along the top of the culmen and has irregular orangish-brown bands on its sides, across the tomia. The beak varies in length from in male toucans and in females; on average, it is long in males and long in females. The base of the beak is black, forming a band thickest at the bottom of the. The tip of the has a large black oval, which shines intensely when seen in light.
The beak looks heavy, but as in other toucans it is relatively light because the inside largely is hollow. The tongue is nearly as long as the bill and very flat. Other than the size difference, there are no external differences between the sexes. Juveniles are duller and shorter-billed than adults. Among standard measurements, the wing chord is, the tail is and the tarsus is. Toco toucans are known to exhibit partial leucism.
Vocalizations
The species' voice consists of a variety of grunting, croaking, or snoring notes similar to those given by toads, including "groomkk", "grunt", "grunnkkt", "kkreekk", "grenggkt", "grr", "ggrekkekk", "arkk-rk", "rrraa", and "rrro-rrro". These notes can be made singly or in a long series, with up to 50 notes given per minute. The toucan's song is a series of grunting notes. Other calls include a murmured "te-te-te" and "ehh-ehh" vocalizations made by immatures of the species. Sounds are also made non-vocally, by hitting the bill against a branch.Although the toco toucan is unlikely to be confused visually with any other species, its vocalizations may be confused for those of the red-breasted and channel-billed toucans. The toco toucan's calls are deeper and less resonant than the calls of both of those species. Additionally, the fast parts of its calls are slower than the corresponding portions of the red-breasted toucan's calls.
Distribution and habitat
The toco toucan is endemic to South America, where it has a wide distribution from the Guianas south to northern Argentina and Uruguay. In the northern portion of its range, it has several disjunct populations, including in the Guianas, in northern Brazil near the Rio Branco, and along the mouth of the Amazon upstream to around Manaus in eastern Amazonas. It is further found from coastal Maranhão southwest to southwestern Brazil, Bolivia, and Pampas de Heath in far southeastern Peru, and south through Piauí and Bahia to northern Argentina and Uruguay. It was previously thought to have gone extinct in Tucumán in northwestern Argentina by the late 1990s, but was rediscovered there in the early 2010s. The species's range in the Amazon rainforest may be increasing due to deforestation. Similarly, it has only been recorded from Uruguay recently; previously, the southward limit of its range was Lagoa dos Patos in Brazil. The recent expansion its range south of the 30th parallel may be caused by escapes of captive individuals or changes in ecological conditions. Toco toucans are generally resident, but will sometimes move en masse in search of food.Unlike other toucans, toco toucans do not inhabit continuous, closed-canopy forests, instead preferring a variety of semi-open habitats such as gallery forests, savannas, forests adjoining water bodies, woodlands and secondary forest, chaco, plantations, orchards, and groves. It is especially common in the Brazilian cerrado, a form of tropical savanna, and gallery forests. It is also common in the wetlands of the Pantanal. It is known to inhabit altitudes of up to.
Behavior and ecology
Toco toucans are typically seen when flying or feeding in treetops, hopping from branch to branch. Their flight is somewhat undulating because they switch between heavy flapping and gliding when flying. Toco toucans, like other toucans, have large home ranges, with an average size of. They are more widely dispersed than other toucans, who do not cross large bodies of water, and are able to sustain flight across water bodies over wide.Toco toucans are less active during the day, occasionally resting in treetops. They are less gregarious than other toucans and usually feed alone or in small groups at fruiting trees. When foraging together, toucans fly from treetop to treetop in single file. Members of a group will often preen each other, although this behaviour usually ends after egg-laying occurs, as mates begin to exclusively preen each other. After the end of the breeding season, toco toucans will sometimes form large flocks that fly around forests searching for fruit. These flocks may sometimes include other species like the white-throated toucan.
Bill
The bill is serrated and is the largest relative to body size of all birds providing 30 to 50% of its body surface area, although another Neotropical species, the sword-billed hummingbird, has a longer bill relative to its body length. Further suggestions have included aid in peeling fruit, intimidating other birds when robbing their nests, social selection related to defense of territory, and as a visual warning.Research has shown that one function is as a surface area for heat exchange. The bill has the ability to modify blood flow and so regulate heat distribution in the body, allowing for the use of the bill as a thermal radiator. In terms of surface area used for this function, the bill relative to the bird's size is amongst the largest of any animal and has a network of superficial blood vessels supporting the thin horny sheath on the bill made of keratin called the rhamphotheca.
In its capacity to remove body heat, the bill is comparable to that of elephant ears. The ability to radiate heat depends upon air speed: if this is low, only 25% of the adult bird's resting heat production is radiated; if high, it radiates as much as four times this heat production. In comparison, the bill of a duck and the ears of an elephant can shed only about 9% of resting heat production. The bill normally is responsible for 30–60% of heat loss. The practice of toco toucans of placing their bills under their wings may serve to insulate the bill and reduce heat loss during sleep. It has been observed that "complexities of the vasculature and controlling mechanisms needed to adjust the blood flow to the bill may not be completely developed until adulthood."
Toco toucan beaks can suffer from a number of deformities, such as crossed mandibles, the absence of up to half of the upper or lower mandible, and perforations.