Toucan – bird with largest bill, its about one third of its body length. This over sized appendages have puzzled scientists from centuries. Charles Darwin says its to attract mate, other interpretations are fruit peeling, nest predation and visual warnings.
Now, team of researchers from Brock University, Canada, and Universidade Estadual Paulista, Brazil, have an answer……Toucan uses its enormous beak to stay cool. Researchers have used infrared cameras on toco toucan (Ramphastos toco), to show the bird dumping heat from its body into its bill, helping it to regulate its body temperature.
The scientists found that as the surroundings got warmer, the toucan’s bill would rapidly heat up, effectively acting as a radiator to draw heat away from the bird’s body, allowing it to stay cool. Conversely, in cooler temperatures, little heat would radiate from the bill, letting the bird conserve its warmth.
As the surroundings heat up, the toucans dump body heat into their bills. The effect was particularly evident at night: at sunset, the birds would, in a matter of minutes, pump out heat from their beaks, lowering their body temperature as they slept. The birds’ bills have a network of blood vessels that can increase or restrict the flow of blood.
By altering blood flow to the bill’s surface, toucans can conserve body heat when it is cold or cope with heat stress by increasing blood flow. Essentially, the large surface area of the bill, and the fact it is not insulated, means that the blood flowing through is able to release heat into the bill, thus cooling the bird. This blood-derived heat in the bill is then dissipated into the air. So it’s an effective radiator.
Other animals also use parts of their bodies to regulate temperature, for example, elephants and rabbits radiate heat from their ears to cool down. Birds do not sweat, so must cope with other mechanisms to deal with elevated temperatures.