As Florida’s wild natural beaches have become more and more scarce, beachside buildings with gravel rooftops have multiplied by the thousands. Shorebirds that nest in the sand have had to adapt. Several species, including black skimmers, least terns, roseate terns and American oystercatchers, have taken to nesting on the plentiful gravel rooftops of buildings near the waterfront. “Building rooftops provide important alternative nesting habitat for shorebirds and seabirds,” said the Florida Fish and Wildlife Conservation Commission, adding that most of the species that nest on rooftops are state-designated threatened species.