Thought by early naturalists to be a fish-storage device, the gular pouch serves primarily to capture fish, which the pelicans typically swallow immediately. To maintain the elasticity of the puch, pelicans peform pouch exercies, throwing the head back with the bill open, or even tucking the head down and turning the punch inside-out over the breast. During breeding displays, the punch becomes brightly colored.
A pelicans’ bill consits of a long, narrow upper jaw and a matching lower jaw formed by two long, flexible bones supporting a deep pounch of skin. When the open b ill is thrust quickly into water, the pounch expands like a balloon, bending the two flexible lower bones ouotward to create a wide opening. After the initial thrust, the bones return to their parallel position, fitting tightly against the upper jaw. Water drains out of the bill, but the prey are trapped inside and swallowed.
So, this little fellow is just doing his exercises to keep his gular pouch nice and flexible.
