The Fish and Wildlife Service (Bureau of Sport Fisheries and Wildlife 1973) listed the Spotted Owl (Strix occidentalis) as a species whose status needed to be determined. Until recently the status of this secretive woodland raptor was unknown by government wildlife agencies and considered to be rare. Furthermore, land practices were reducing the habitat of the Spotted Owl. For these reasons, the California Department of Fish and Game and the United States Forest Service cooperatively initiated and financed this study in July 1973. In 1974 the National Park Service became involved.
In 1973 I conducted surveys in the forested mountains in northwestern California. From March to September 1974 surveys were conducted throughout the remaining areas of coniferous forest in California. During the 1975, 1976 and 1977 breeding seasons, voids in the range were checked and known sites monitored by the author and other agency biologists.