Blue-footed booby
The blue-footed booby is a marine bird native to subtropical and tropical regions of the eastern Pacific Ocean. It is easily recognizable by its distinctive bright blue feet, which is a sexually selected trait and a product of their diet. Males display their feet in an elaborate mating ritual by lifting them up and down while strutting before the female. To stay cool in very hot environments, Blue-footed Boobies sometimes defecate on their feet (a behavior called urohydrosis). They also flutter the skin of their throats (the gular pouch) by rapidly vibrating bones in their throat, which creates evaporative cooling through the open mouth. The blue color of Blue-footed Booby’s feet varies in its intensity. Boobies with bluer feet appear to have more success in finding a mate than birds with duller blue feet. One study looked at foot color in relation to the health of young chicks and found that healthiest chicks tended to have fathers with intensely blue feet—possibly an indication of the father’s ability to keep himself well fed.