The Rachel Carson National Wildlife Refuge was established to preserve ten important estuaries that are key points along migration routes of waterfowl and other migratory birds. During harsh winters, the refuge's marshes provide vital food and cover for waterfowl and other migrating birds at a time when inland waters are frozen. The refuge also supports piping plover, least terns, peregrine falcons, bald eagles, and other state and federally protected species. Nesting success of plover and terns has benefitted from the increased habitat protection. In addition to anadromous fish, many commercially and recreationally important fin and shellfish rely on these coastal wetlands as critical nursery areas.