Toco Toucan - Behavior

Behavior

The Toco Toucan eats fruit (e.g. figs and Passiflora edulis) using its bill to pluck them from trees, but also insects, frogs, small reptiles, and eggs and nestlings of birds. It also has been known to capture and eat small adult birds in captivity. The long bill is useful for reaching things that otherwise would be out-of-reach. It is also used to skin fruit and scare off predators. It is typically seen in pairs or small groups. In flight it alternates between a burst of rapid flaps with the relatively short, rounded wings, and gliding. They are poor flyers, and usually hop from tree to tree. Nesting is seasonal, but timing differs between regions. The nest is typically placed high in a tree and consists of a cavity, at least part of which is excavated by the parent birds themselves. It has also been recorded nesting in holes in earth-banks and terrestrial termite-nests. Their reproduction cycle is annual. The female usually lays two to four eggs a few days after mating. The eggs are incubated by both sexes and hatch after 17–18 days. These birds are very protective of themselves and their chicks.

The bill 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. It was called by Buffon a “grossly monstrous” appendage. Diverse functions have been suggested. Charles Darwin suggested it was a sexual ornament: “toucans may owe the enormous size of their beaks to sexual selection, for the sake of displaying the diversified and vivid stripes of colour with which these organs are ornamented". 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 bird, allowing it to use its 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 to as much as four times this heat production. In comparison the bill of a duck and the ears of elephant can shed only 9 to 91% of resting heat production. The bill normally is responsible for 30 to 60% of heat loss. The practice of Toco Toucan's 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."