The Susquehanna River and nearby Chesapeake Bay are important parts of the Atlantic Flyway, one of four major North American migratory routes for waterfowl, along which more than a million waterfowl migrate or spend the winter each year, including 28 species of ducks, geese, and swans. The Susquehanna's abundant waterfowl made it a popular hunting area for Native Americans and early European settlers who relied on the flyway as a source of food. In the 1800's and early 1900's, waterfowl populations plummeted because unregulated commercial hunters known as market gunners used punt guns, duck traps, and other mass-kill weapons. Today waterfowl hunting remains a popular outdoor recreation, and hunters and organizations such as the Susquehanna River Waterfowlers Association and the Susquehanna River Wetlands Trust support habitat protection, anti-overhunting laws, nesting site creation, wetland restoration, and education programs to help restore waterfowl populations throughout the Atlantic Flyway.