Birds
Keel-billed Toucan
Ramphastos sulfuratus · also called rainbow-billed toucan, sulfur-breasted toucan
The keel-billed toucan looks like a bird designed by committee: a compact black body, a lemon-yellow face and chest, bright blue feet, and then an enormous bill splashed with green, orange, red, and blue. That bill is the whole story of the species.
Overview
Ramphastos sulfuratus ranges from southern Mexico to northern Colombia, in lowland and foothill forest. It is 42–55 cm long and weighs 380–500 g. It eats mostly fruit, swallowed whole so the seeds pass intact, but will also take insects, lizards, snakes, and the eggs and chicks of other birds.
The bill
The bill is about a third of the bird’s length but weighs very little: under a thin keratin shell is an open lattice of bony struts. It lets the toucan perch on a solid branch and still reach fruit on twigs too thin to stand on, and it doubles as a radiator — the bird routes blood through it to shed heat when warm and hold heat when cool.
Getting around
Toucans are poor fliers, crossing the canopy in short undulating bursts and mostly hopping and climbing. To sleep in a tree cavity, several birds squeeze in together, each folding its tail over its back and tucking its bill under a wing.
Status
The keel-billed toucan is Least Concern but slowly declining with lowland forest clearance. It is the national bird of Belize.
Keel-billed Toucan: common questions
Is the toucan's bill heavy?
Surprisingly not. It looks like it should overbalance the bird, but the bill is mostly hollow. Inside a thin, hard outer layer of keratin is an open framework of slender bony rods and membrane, a bit like foam or a honeycomb, so the whole structure is stiff and large but very light. That is why a toucan can hold a big fruit at the tip of a long bill without straining, and why it can move a bill that size quickly. The trade-off is that the bill is not strong; it is no good for heavy digging or serious fighting.
What is the giant bill actually for?
Several things at once, which is probably why it evolved to be so big. It lets the bird sit on a stout branch and still reach fruit and berries dangling from twigs that would never hold its weight. It is used to reach into tree holes for eggs and chicks. Its bright pattern is a signal to other toucans in courtship and social life, and the birds fence and pass fruit to each other with it. And research on toucan bills has shown they work as adjustable radiators, letting the bird release heat through the bill in warm conditions and reduce that loss when it is cool.
Where does the keel-billed toucan live?
It is a bird of the American tropics, ranging from southern Mexico down through Guatemala, Belize, Honduras, Nicaragua, Costa Rica, and Panama into northern Colombia and the far northwest of Venezuela. It keeps to lowland and foothill forest, including tall second growth and forest edges and clearings with scattered fruiting trees, generally below about 1,200 m. It moves around locally to follow which trees are in fruit, and small noisy flocks are a common sight in the canopy across that range.
What sound does it make?
Not the loud musical call people might expect. The keel-billed toucan gives a dry, monotonous, croaking series often compared to a frog, sometimes with a rattling or grunting quality, repeated for long stretches from a high perch. Birds often call together, and a group can keep it up through much of the day. The sound carries well through the forest and helps the flock stay in contact as it moves.