Massachusetts is located along the Atlantic Flyway, a major route for migratory waterfowl along the Atlantic coast. Lakes in central Massachusetts provide habitat for the common loon, while a significant population of long-tailed ducks winter off Nantucket. Small offshore islands and beaches are home to roseate terns and are important breeding areas for the locally threatened piping plover. Protected areas such as the Monomoy National Wildlife Refuge provide critical breeding habitat for shorebirds and a variety of marine wildlife including a large population of gray seals.