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Cooper's Hawk
Accipiter cooperii
California Department of Fish and Game "Species of Special Concern"
Life History
This is a short winged, long tailed hawk. The Cooper's hawk is quite similar to the
sharp-shinned hawk but is larger with a longer, more rounded tail. This hawk measures 14 to
20 inches in length with a 29 to 37 inch wing span. The sexes are generally monomorphic,
females growing larger than males and are almost the size of a crow. The adults have a
proportionately large, squarish head and neck compared to the sharp-shinned hawk, and there
is more contrast between the blackish crown and gray nape. The legs are yellow in color and
when perched the wing tips reach less than half way to the tip of the tail. Sometimes the
wings assume a dihedral formation while soaring and a loud, long scream similar to that of the
red-tailed hawk's is also sometimes emitted.
Cooper's hawks nest in deciduous trees in crotches or cavities that are usually 20 to 50
feet off the ground. This hawk will also nest in conifers on horizontal branches or in the main
crotch that is often just below the lowest of the live limbs. The nest is a stick platform lined
with bark. Nests are usually placed in second growth coniferous stands or in the deciduous
riparian areas that are closest to streams.
Breeding takes place March through August with the peak activity being May through
July. A single clutch of two to six eggs (usually four to five) is laid. If a clutch of eggs is lost
to predation or weather, a second clutch may be laid if it is not too late in the season.
Although four to five eggs usually hatch, fledgling success averages about two per breeding
pair per year.
This accipiter is a permanent breeding resident throughout most of the wooded areas of
California. They breed in the southern Sierra Nevada foothills, the New York Mountains, the
Owens Valley, as well as other areas in southern California. They range through a vast area
from sea level to above 9000 feet. They prefer dense stands of live oaks, riparian deciduous,
or other various forest habitats that are near water.
This robust hawk exhibits year-round diurnal activity. It is able to kill other bird prey
species because of its speed and agility. It often dashes suddenly from a
preferred perch in dense cover and pursues the prey in the air and through the tree branches.
Dense cover is important for the ambush style hunting exhibited by this hawk.
In California, they are mostly year-round residents. Some Cooper's hawks from the
more northern parts of the country migrate into California . They also move down slope and
south from the areas containing heavy snow in autumn and return in the spring.
Breeding numbers of this hawk have declined in recent decades. They may compete to
a certain extent with sharp-shinned hawks for breeding and roosting habitat. Pesticides,
human disturbance, and destruction of riparian habitat have also played significant roles in
reductions in numbers. Identification and protection of breeding habitat is needed to prevent
current population densities from declining.
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