 By the late 19th century, plume hunters had nearly wiped out the snowy egret population of the United States in pursuit of the bird's delicate feathers, which were commonly used by milliners for the adornment of ladies' hats.Alarmed by this trend, McIlhenny searched the Gulf Coast and located several surviving egrets, which he took back to his estate on Avery Island.There he turned the birds loose in a type of aviary he called a "flying cage," where the birds soon adapted to their new surroundings.