Written by: C. Polite
Reviewed by:L. Kiff
Edited by: L. Kiff
DISTRIBUTION, ABUNDANCE, AND SEASONALITY
A common, permanent resident throughout the
state from sea level to 2100 m (0-7000 ft),
occasionally to 3200 m (10,500 ft). Exploits a variety of forests
with meadows and other
openings, extending from valley foothill hardwood to mixed conifer
habitats. Commonly feeds
and breeds in riparian, conifer, chaparral, and desert habitats.
SPECIFIC HABITAT REQUIREMENTS
Feeding: Usually makes low, rapid flight
from perch to capture prey on ground. Rabbits,
rodents, and other small to medium-sized mammals usually make up 90%
of the diet. Also
eats birds (occasionally smaller or young raptors; Wiley 1975b), amphibians,
and arthropods. Frequently forages in meadows and woodland or
forest openings, or along
Cover: Requires trees with dense foliage
for roosting; often uses thickly wooded canyons.
Reproduction: Nests in abandoned hawk,
crow, raven, or squirrel nest, in cave or crevice,
on cliff ledge, occasionally in snag or tree cavity (Call 1978).
Nests in trees usually 12-21 m
(40-70 ft) above ground.
Water: Most water requirements probably
met from prey (Bartholomew and Cade 1963).
Will drink water in captivity.
Pattern: Frequents forested habitats;
feeds especially in edges, openings, and meadows.
SPECIES LIFE HISTORY
Activity Patterns: Yearlong, nocturnal
and crepuscular activity.
Seasonal Movements/Migration: Mostly
not migratory, but will move upslope and
downslope in response to weather conditions.
Home Range: In Wyoming, home range varied
from 1.2 to 2.9 km² (0.4 to 1.1 mi²), with an
average of 2.1 km² (0.8 mi²). In eastern Oregon, home
range averaged 12.1 km² (4.7 mi²). In
Michigan farmland, nesting density varied from 0.04 to 0.08 pair per
km² (0.1 to 0.2 per mi²),
and wintering density varied from 0.12 to 0.15 individuals per km²
(0.3 to 0.4 per mi²)
(Craighead and Craighead 1956).
Territory: Average territory was 65 ha
(160 ac) in oak habitats in Kansas (Fitch 1958).
Male defends territory throughout breeding season more aggressively
Reproduction: Breeds from mid-January
through June, peak usually March through May.
Clutch size 1-6; average 3; often laid in February or March.
Incubation 26-35 days,
semialtricial young fledge in 35-56 days. Male may assist with
nest activities. Craighead and
Craighead (1956) reported fledging success (young fledged/eggs laid)
of 27% and 50% in
Michigan, and 89% in Wyoming.
Niche: Golden eagles and humans may be
the only predators (Hoechlin 1976).
Competitors for food include Cooper's hawks, American kestrels, and
other large owls.
Population numbers respond to prey abundance.
Bartholomew, G. A., and T. J. Cade. 1963. The water economy
of land birds. Auk 80:504-
Bent, A. C. 1938. Life histories of North American birds
of prey. Part 2. U.S. Natl. Mus. Bull.
Call, M. W. 1978. Nesting habits and survey techniques
for common western raptors.
U. S. Dep. Inter., Bur. Land Manage., Portland
OR. Tech. Note No. 316. 115pp.
Craighead, J. J., and F. C. Craighead, Jr. 1956. Hawks,
owls and wildlife. Stackpole Books,
Harrisburg, PA. 443pp.
Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's
handbook. Simon and
Schuster, New York. 785pp.
Fitch, H. S. 1947. Predation by owls in the sierran foothills
of California. Condor 49:137-151.
Fitch, H. S. 1958. Home ranges, territories, and seasonal movements
of vertebrates of
the Natural History Reservation. Univ.
Kans., Lawrence. Publ. Mus. Nat. Hist. 11:63-
Grinnell, J., and A. H. Miller. 1944. The distribution
of the birds of California. Pac. Coast
Avifauna No. 27. 608pp.
Guiguet, C. J. 1960. The Birds of British Columbia (7).
The owls. Brit. Col. Prov. Mus.,
Vancouver. Handb. No. 18. 62pp.
Harrison, C. 1978. A field guide to the nests, eggs and
nestlings of north American birds. W.
Collins Sons and Co., Cleveland, OH.
Hoechlin, D. R. 1976. Development of golden eaglets in
southern California. West. Birds
Karalus, K. E., A. W. Eckert. 1974. The owls of North America.
Doubleday Co., Garden City
Marti, C. D. 1974. Feeding ecology of four sympatric owls.
Murray, G. A. 1976. Geographic variation in the clutch
size of seven owl species. Auk
Wiley, J. W. 1975b. Relationships of nesting hawks with
great horned owl. Auk 92:157-159.
Compiled from information from California Department of Fish and Game - California Interagency Wildlife Task Group