Strix occidentalis
L 16″ W 42″
Habitat: This uncommon owl occurs in most old-age conifer associations in the western United States. Forsman (1976) located 123 pairs in Oregon, and 95 percent occupied undisturbed old-growth conifer forests. Karalus and Eckert (1974) described the habitat as being dense fir forests, heavily wooded cliffsides, narrow canyons, and sometimes stream valleys well stocked with oak, sycamore, willow, cottonwood, and alder.
Nest: Forsman (1976) found spotted owls nesting in the holes of living old-growth conifers, particularly Douglas-fir. Nest trees typically had secondary crowns and broken tops caused by parasite infection. Cavities were located inside the tops of hollow trunks 62 to 180 feet above ground. Dunn (1901) reported spotted owls nesting in cavities in live and dead oak and sycamore trees. Spotted owls also nest in cavities in cliffs, and occasionally in abandoned nests of other large birds (Bent 1938).
Food: The major food items of the spotted owl are mammals and birds, with occasional insects and amphibians. Forsman (1976) found that mammals made up 90 percent of the total biomass taken; the major prey species were flying squirrels and wood rats. Marshall (1942) examined 23 pellets and stomach contents of 5 spotted owls and found 6 bats, 4 mice, 31 crickets, 12 flying squirrels, 1 mole, 1 shrew, 4 songbirds, 2 smaller owls, and 1 amphibian.
Boreal owl
Aegolius funereus
L 10″ W 24″
