NATURAL HISTORY

CALIFORNIA SPOTTED OWL } Strix occidentalis occidentalis
FAMILY: Strigidae

DESCRIPTION: The spotted owl is a medium-sized owl with dark brown eyes, a round head with pale brown facial disks, and a grayish-colored bill. Its body is brown and heavily spotted with white on the breast and belly; the wings, back, and head have fewer spots. The owl’s plumage is soft and fluffy, which can make its head appear overlarge. Females grow to be an average of 19 inches in length with a 43-inch wingspan; males are about 18 inches long with a 42-inch wingspan. California spotted owls are intermediate in color between the darker northern spotted owl and the lighter Mexican spotted owl.

HABITAT: The spotted owl lives in mature and old-growth forest characterized by a dense, multi-layered forest canopy, old trees, large, standing dead trees, and abundant woody debris.

RANGE: The California spotted owl currently occurs in the Sierra Nevada and in the major mountains of southern California, including the San Bernadino, San Gabriel, Tehachapi, north and south Santa Lucia, Santa Ana, Liebre/Sawmill, San Diego, San Jacinto, and Los Padres ranges.

MIGRATION: California spotted owls are generally nonmigratory, remaining within the same home ranges all year. However, in the Sierra Nevada, some individuals migrate downslope to winter ranges.

BREEDING: Spotted owls generally reach reproductive maturity at two years of age. Pairs breed in the spring and form close bonds that can re-occur over many years. Egg laying peaks in mid-April and eggs hatch about 30 days after being laid. Spotted owls typically raise one or two young and do not breed every year.

LIFE CYCLE: Spotted owl chicks fledge 34 to 36 days after hatching. The species is a relatively long-lived one, with many birds surviving to be more than 10 years old.

FEEDING: Spotted owls are “perch-and-pounce” predators, feeding on a variety of birds and small mammals — particularly flying squirrels and dusky-footed wood rats. Other prey includes frogs, lizards, and insects. These owls forage primarily at night, but have been observed hunting during the day, especially while raising young.

THREATS: Logging, urbanization, wildfire, and competition from the invasive barred owl threaten the California spotted.

POPULATION TREND: Old-growth forests in the range of the California spotted owl have declined by roughly 90 percent, with an indeterminable but likely severe impact on the owl. Studies from the 1990s showed annual declines in California spotted owl populations of five to 10 percent. A recent reanalysis of population data by the U.S. Forest Service found similar declines, but because of a lack of statistical certainty, the Service concluded that the rate of decline was uncertain.

 

Photo by Ilya Katsnelson