Written by: C. Polite, G. Ahlborn
Reviewed by: S. Bailey
Edited by: S. Bailey
DISTRIBUTION, ABUNDANCE, AND SEASONALITY
Common resident throughout California, wintering
in all habitats except high elevations.
Also a winter migrant. Fairly common on Channel Islands.
Occurs in most open habitats, in a
variety of shrub and early successional forest habitats, in forest
openings, and various
SPECIFIC HABITAT REQUIREMENTS
Feeding: Takes small mammals, birds,
insects, earthworms, reptiles, and amphibians.
Perches and pounces, pounces from a hover, or catches flying insects.
Rarely pursues prey
on wing. Caches prey near nest in cracks in trees or rocks (Collopy
1973). Perch may be
tree, snag, rock, utility pole or wire, fence post (Grinnell and Miller
1944). Forages in open
Cover: Seeks cover in a variety of cavities
in trees, snags, rocky areas, banks, and
Reproduction: Nests in cavities in trees,
snags, rock crevices, cliffs, banks, and buildings.
Bent (1938) reported nests in cavities in sycamores, willows, and cottonwoods.
construct a stick nest. Often uses cavities excavated by northern
flickers and Lewis'
woodpeckers. In Oregon, Thomas (1979) estimated that the minimum
dbh tree required by
these 2 woodpeckers was 31 cm (12 in) and 38 cm (15 in), respectively.
Water: Drinks water in captivity (Roest
1957). Has a high tolerance to heat and aridity.
Pattern: Forages in open and partially
open areas of most habitats. Needs cavities near
SPECIES LIFE HISTORY
Activity Patterns: Yearlong, diurnal
Seasonal Movements/Migration: At higher
elevations, moves downslope for winter and
upslope for summer. Individuals from north migrate into California
for winter (Grinnell and
Miller 1944). Residents often maintain pair bond throughout the
Home Range: Prebreeding home range twlce
as large as breeding home range on the
east side of the Sierra Nevada (Balgooyen 1976). At various other
locations, winter home
ranges varied from 154-452 ha (380-1117 ac) (Enderson 1960, Mills 1976).
Territory: Balgooyen (1976) reported
that 32 territories averaged 109 ha (270 ac). In the
Los Angeles area, Cade (1955) reported that defended territories averaged
10 ha (25 ac). In
various locations, summer breeding territories varied from 78-399 ha
(192-987 ac) (Enderson
1960, Mills 1976).
Reproduction: Breeds from early April
to August, with peak activity May and June. Eggs
laid mid-May to late June. Average clutch size 4-5, range 3-7.
Incubation 28-31 days; young
fledge after 29-31 days.
Niche: May be preyed upon by larger raptors.
Balgooyen (1976) suggested that tree
squirrels may destroy nests. May compete with other cavity nesters:
owls, bluebirds, nuthatches, chipmunks, squirrels. Female larger
than male, allowing pair to
partition food resources more effectively. Ectoparasites include
lice, black flies (Roest 1957),
calliphorid flies, and milichiid flies (Balgooyen 1976).
Balgooyen, T. G. 1976. Behavior and ecology of American
kestrel (Falco sparverius L.) in
the Sierra Nevada of California. Univ.
Calif. Publ. Zool. 103:1-87.
Bent, A. C. 1938. Life histories of North American birds
of prey. Part 2. U.S. Natl. Mus. Bull.
Cade, T. J. 1955. Experiments on winter territoriality
of the American kestrel (Falco
sparverius). Wilson Bull. 67:5-17.
Collopy, M. W. 1973. Predatory efficiency of American kestrels
wintering in northwestern
California. Raptor Res. 7:25-31.
Enderson, J. H. 1960. A population study of the sparrow
hawk in east-central Illinois.
Wilson Bull. 72:222-231.
Grinnell, J., and A. H. Miller. 1944. The distribution
of the birds of California. Pac. Coast
Avifauna No. 27. 608pp.
Mills, G. S. 1976. American kestrel sex ratios and habitat
separation. Auk 93:740-748.
Roest, A. I. 1957. Notes on the American sparrow hawk.
Thomas, J. W., ed. 1979. Wildlife habitats in managed forests:
The Blue Mountains of
Oregon and Washington. U.S. Dept. Agric.,
For. Serv., Portland, OR. Agric. Handb. No.
Compiled from information from California Department of Fish and Game - California Interagency Wildlife Task Group