California Spotted Owl Habitat Selection in the Central Sierra Nevada

We examined habitat selection by California spotted owls (Strix occidentalis occidentalis) at 3 spatial scales: landscape, habitat patch, and microsite. We compared landscape characteristics within 457-ha circles surrounding 25 owl activity centers to randomly selected areas of equal size. Owl activity centers were defined as the geometric center of the minimum convex polygon enclosing roosts and nests located between 1986 and 1992. Baxter-Wolf indices of habitat interspersion were lower in owl sites than in random sites suggesting that owl sites contained fewer habitat patches. Ninety-seven percent of the habitat patches in which owls roosted were characterized by residual (i.e., >100 cm dbh [diameter at breast height]) trees. Owl roost and nest sites also were characterized by residual trees and high structural diversity. Current forest classification procedures generally fail to detect this residual tree component, which has important implications for habitat conservation of the owl.