Many birds are found on Sheffield Island and more than elsewhere, according to a brochure published in 2001 by the South Western Regional Planning Agency, but according to a July 2007 article in "Darien, New Canaan & Rowayton" magazine, Cockenoe island is now the largest home for birds, who have been in decline on the other islands. Sheffield Island, according to the planning agency brochure, has a "considerable nesting potential" for osprey, herons and other migratory species. Many wading birds, shore birds, songbirds and terns live on the island, including the roseate tern. Brant, scoters, black duck and other waterfowl can be found in the waters surrounding the island.