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The toco toucan ( Ramphastos toco) 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 massive 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 1,750 m (5,740 ft). 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.
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 language word for toucan, and may mean "bone-nose". Toco toucan is the official common name designated by the International Ornithologists' Union (IOU). 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 Chimane language, 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 (groups of organisms descending from a common ancestor): 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 toucan, and channel-billed toucans. He further postulated that the toco toucan was basal (closest to the root of the phylogenetic tree) 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:
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 173 to 215 mm (6.8 to 8.5 in) in male toucans and 158 to 202 mm (6.2 to 8.0 in) in females; on average, it is 200.5 mm (7.89 in) long in males and 178.6 mm (7.03 in) 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.
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.
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, Riparian forest, and secondary forest, Humid 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 .
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 Preening 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.
Research has shown that one function is as a surface area for Heat transfer. 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.
Plants that have been recorded as contributing majorly to the toco toucan's diet include Genipa americana, Ficus luschnatiana, and Virola sebifera in gallery forest, Schefflera macrocarpa, Copaifera langsdorffii, Didymopanax morototoni, and Nectandra cissiflora in the cerrado, and Guibourtia hymenaefolia and D. morototoni in semi-deciduous forests. During the dry season when the availability of fruits declines, toco toucans will also feed on flowers of species such as Handroanthus chrysotrichus and Erythrina fusca.
The insects most commonly consumed by toco toucans are caterpillars and termites. Toco toucans also feed on small vertebrates such as lizards, nestlings, and small birds. In the wild, toucans prey on the nests of icterid blackbirds, tyrant flycatchers, puffbirds, and parrots, and especially target the nests of yellow-rumped caciques. The largest known birds whose nests are predated upon by the toco toucan are the hyacinth macaw and buff-necked ibis; the nestlings of the latter weigh , compared to the toucan's body mass of around , and are killed by breaking their necks with sideways movements of the toucan's beak. In captivity, toucans will feed on a number of smaller birds that are placed with them, such as Toxostoma thrashers, house sparrows, Inca doves, cactus wrens, and Gambel's quails.
Nesting is seasonal, but timing of the breeding season differs between regions. Breeding has been observed from September to January in Amazonas and Maranhão and from September to February in São Paulo, Rio de Janeiro, Paraná, and Paraguay. In eastern Argentina and Rio Grande do Sul, it occurs from October to February, and in Goiás, Minas Gerais, and Bahia, it lasts from November to February. It has been documented from December to June in Bolivia and western Argentina, and from May to June in Piauí. Nesting occurs in cavities, which are usually made in trees such as coral cockspur and Pinus elliottii, but which can also be in stream banks or termite mounds. Nests are sometimes made in cavities excavated by other species of birds: recorded instances include nests in cavities made by Campo flicker and cream-backed woodpeckers. Successful breeding has also been observed in urban areas, although high levels of human-caused disturbances, such as construction activities, around the nest can lead to abandonment by the parents. Captive birds have been observed cleaning their nests early on, but the nests are eventually filled with droppings and fruit seeds.
Toucans usually breed annually in the wild, but have been reported breeding multiple times a year in captivity. Females lay two to four eggs, which are incubated by both parents for 17–18 days, after which they hatch. Chicks can be detected by the loud begging calls they make in the absence of their parents. Hatchlings are initially fed mostly insects, with the proportion of fruit in their diet increasing as they age. Chicks fledge 43–52 days after hatching.
Toco toucans are also an especially important seed disperser for the manduvi tree, being responsible for over 83% of the seed dispersal of that species. The endangered hyacinth macaw nests near-exclusively in hollows in manduvi trees, leading to an indirect dependency on the toco toucan, despite the latter species being responsible for over half of egg predation of the hyacinth macaw. Toco toucans may also be ecologically significant nest predators for species which nest in areas with few other terrestrial predators, such as cliffs.
No specific predators of the toco toucan are known, but toucans in general are known to be hunted by monkeys and large birds of prey. Several species of chewing lice, such as Austrophilopterus cancellosus and Myrsidea witti, are known to parasitize the toco toucan. The species is also parasitized by the protozoans Plasmodium nucleophilum, P. huffi, P. pinottii, Toxoplasma gondii, and Giardia duodenalis, Trichomonas parabasalids, and trematodes.
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