Various functions of the beak have been proposed. Charles Darwin believed that it was a sexual ornament. Other suggestions include helping to peel fruit, intimidating other birds that rob their nests or defend their territory, or as a visual warning to a potential enemy.
However, research has shown that the only function is heat exchange. With a network of superficial blood vessels supporting a thin keratinized sheath on its beak, it has the ability to modify blood flow and thus regulate heat distribution in the body - it can be used as a radiator. The beak of the toco toucan has been compared to the ears of an elephant in terms of its ability to radiate heat. The ability to radiate heat depends on the air velocity; if it is low, only 25% of the resting heat of an adult bird is radiated; if it is high, the emission is four times higher.
The practice of toco toucans is to place their beaks under their wings, which can serve to insulate the beak and reduce heat loss during sleep.
