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About the California Spotted Owl

This California Spotted Owl (CSO) information repository has been created as a place for all to gather information and resources on CSO. Information is posted from a variety of sources. Copyright laws limit some postings to links to the publishing journals or authors.We hope that you find this site easy to use and helpful!

The California spotted owl (Strix occidentalis occidentalis) is a nocturnal, medium-sized owl species that preys primarily on small mammals such as woodrats and flying squirrels. As with most raptor species, the females are larger than the males. California spotted owls generally begin nesting in early April and usually fledge young by mid-June. Nests are selected from existing structures such as natural cavities, broken tree tops, and the abandoned platform nests of other raptors. The female incubates the eggs, while the male provides food to the incubating female. After the eggs hatch, both parents supply food to the young. The typical brood size is 1 or 2 young, although 3 hatchlings are possible. After fledging, the juveniles continue to receive food from the parents until late August or early September. At that time, the juveniles disperse to new locations that are 3 to 50 miles away from the natal territory. Spotted owls communicate using a wide array of vocalizations including a series of hoots, barks and soft whistles.
Owl photo by Sheila Whitmore