The Preserve is home to California's largest remaining valley oak riparian forest, and is one of the few protected wetland habitat areas in the state. The Cosumnes River is the only free-flowing river left in California's Central Valley. Only minutes from California's capital, this is a critical stop on the Pacific Flyway for migrating and wintering waterfowl. Over 200 species of birds have been sighted on or near the Preserve, including the state-listed threatened Swainson's hawk, greater and lesser sandhill cranes, Canada geese, and numerous ducks. The Preserve includes 11,500 acres of current and potential wetlands and valley oak forests.