Even Charles Darwin himself debated about what the toucan's beak was used for eventually settling for "toucans's 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 onamented". Fast forward to 2009 and a group of scientists discover that the toucan's beak is actually one of the largest thermal windows in the animal kingdom rivaling elephants ears in it's ability to radiate body heat. The video below shows how they used infrared thermography to show how toucan's thermoregulate their temperature.

The beak itself is made up of a honeycomb structure which actually makes the beak really light. The black band on the toucan's beak is unique to them,behind that band is the nostrils!                                                                     

                                                                  Photo courtesy of Adventures in Toucanland.