There is no mistaking that bill. Toucans have one of the brightest, most colourful, largest and heaviest bills in the world. And yes, they are the noisiest birds in the world, often heard croaking away in their rainforest homes of Mexico and Argentina. But scientists are not sure of the bill?s function. Since the toucan?s enemies are much stronger than itself, the beak would surely not serve as any weapon.