Sibley Lake National Wildlife Refuge in North Dakota covers 1,077 acres as a privately owned easement refuge managed by the U.S. Fish and Wildlife Service. Established to protect habitat for migratory birds, white-tail deer, and other mammals, it includes a 525-acre freshwater marsh that is especially important for migrating birds. The refuge is overseen by the Valley City Wetland Management District and forms part of the Arrowwood National Wildlife Refuge Complex.