The 5200 acre refuge was established in 1976, to protect one of the country's largest undeveloped mangrove ecosystems. The refuge consists of over 6,400 acres of mangrove forest, submerged seagrass beds, cordgrass marshes, and West Indian hardwood hammocks. Approximately 2,800 acres of the refuge are designated by Congress as a Federal Wilderness Area. The refuge was created to safeguard and enhance the pristine wildlife habitat of Sanibel Island, to protect endangered and threatened species, and to provide feeding, nesting, and roosting areas for migratory birds. Today, the refuge provides important habitat to over 245 species of birds.