Click on image to enlarge.
During the mating season (March through May along the Gulf Coast), great egrets grow long plumes that trail from their backs and extend beyond their tail. At other times of the year, they lose these plumes.
They also undergo two more changes. Their bills, which are normally a dull yellow/brown color become almost orange. They also grow green patches next to their eyes called lores. This area extends from the eyes to the upper base of the beak.