The Great Black-backed Gull has plumage that evolves through the seasons and as it ages. The largest gull in the world, its feathers were used for the fashions in the 1800s. Populations increased and their presence spread further south after the collapse of the feather trade in the early 1900s. Fifty-one were found i Central Park in this year's Bird Count. Audubon Society, Flightless Bird, Gulls, Christmas Bird, Birds Of Prey, Central Park, Bald Eagle, Wisconsin, Feathers