Coopers Hawk
Accipiter cooperi
 The Coopers Hawk (or
proper Cooper's Hawk) is North America's medium size Accipiter (about the same
size as a crow). "Coops" breed throughout North America in forested areas.
They do breed in deserts and other open areas, but must have trees to nest.
As noted in the
Accipiters page,
Coopers Hawks (COHA) are reverse size dimorphic, meaning that the females are
larger than the males.
Length:
Males: 14-16 inches (37-41 cm)
Females: 16-19 inches (42-47 cm)
Wingspan:
Males: 28-30 inches (70-77 cm)
Females: 31-34 inches (79-87 cm)
Weight:
Males: 302-402 grams (10-14 oz)
Females: 479-678 grams (17-24 oz)
(above data from
A Photographic Guide to North American Raptors ,
Wheeler & Clark 1995). We highly  recommend this
book for anyone interested in raptors.
(Wheeler & Clark data are presumed to be primarily from eastern birds (Cape May, NJ migration monitoring))
We present data for wing chord and weight that we collected for both Eastern and Western Cooper's
Hawks. We have found (as have others) that
Eastern "Coops" are slightly larger on average than Western birds (see data below).
Eastern Cooper's Hawk Wing Chord*
Males: mean 236.1 mm (230-250)
Females: mean 262.6 mm (254-268)
Eastern Cooper's Hawk Weight
Males: mean 327.7 g (285-380)
Females: mean 488.7 g (456-600) Western Cooper's Hawk Wing Chord*
Males: mean 224.9 mm (210-240)
Females: mean 255.4 mm (241-270)
Western Cooper's Hawk Weight (No Food in Crop)**
Males: mean 281.7 g (239-329)
Females: mean 424.7 g (326-549)
Western Cooper's Hawk Weight (Food in Crop)**
Males: mean 300.9 g (268-382)
Females: mean 453.3 g (360-556)
*Wing Chord is measured from from the wrist to the tip of the longest primary feather of one wing. The primary feathers have a
natural camber (bend), and can be measured flattened or un-flattened. We
always measure un-flattened wing chord.
**Raptors store food in a crop (pouch in the throat area). Food in the crop or stomach can effect the bird's
weight. We can not know how much food is in the stomach, but we can
estimate the amount of food in the crop. We score the crop on a 0= no food
in the crop to a 3 = full crop. A full crop in a Cooper's hawk could weigh
as much as 60-70 grams. Keep in mind, we are not likely to capture birds
that are not hungry, so only a few birds have crops and very few birds have
large crops.
Diet: Cooper's Hawks prey mostly on small to medium sized birds and small mammals, but they
also take other prey such as lizards, insects and frogs, but they occasionally try to take larger prey.
I have even pulled out a porcupine spine found stuck in a Cooper's Hawk!
I don't know what the Coop was thinking or how big the porcupine was, but I
doubt the porcupine attacked the Coop!
(Toland 1985), found the diet of Coopers Hawks in Missouri consisted of mostly
of birds (87% of prey numerically and 65% by biomass) and mammals (34% biomass)
and 1% was prey other than birds or mammals.
Nest: Usually 18 - 28 inches in wide and 7-30 inches deep, with an inner cavity
of 7 inches diameter and 2 - 4 inches deep. The nest is made of
sticks and twigs. The nest cup is
lined with chips or flakes of bark (from pine or oak) and sometimes fresh greenery.
The nest is usually placed on horizontal branches against the trunk of
coniferous trees, or in the crotch of a deciduous tree 20-60 feet above the ground.
About 50% of nests are 35-45 feet high.
I have seen a Cooper's Hawk Nest that was only 12 feet above the ground in a
Gambel Oak (Quercus gambelii). The area was a rolling open
sage-brush area, with small patches of oaks in the washes.
Nest Construction usually begins in March or April.
Eggs: Clutch size is usually between 3-6 eggs. About
half of nests have 4 eggs and about 25% of the nests have 5 eggs.
Average size: 49 X 38.5 mm. (Bent, 1937)
Eggs are usually bluish or greenish
white, then fade to dirty white. Eggs can be un-marked or have some brownish
spots.
Egg laying usually begins in early May to early June. Eggs are usually laid
30-48 hours apart.
Incubation period: Incubation may not start until most of
the eggs are laid and is usually about 24 days. If incubation began after
all the eggs were laid, then all chicks would hatch in 24 or 25 days. If
incubation begins with the 3rd egg of a 4 egg clutch, then incubation would last
an additional 1-2 days. If incubation begins with the 3rd egg of a 5 egg
clutch, then incubation would last an additional 3-5 days for a total of 27-30
days.
The chicks usually hatch a few days apart.
Fledging: Chicks usually begin "branching" from the nest
before they can fly at about 28-30 days, but make their first flight between
32-36 days after hatching. Fledging usually occurs between early July to
early August.
Longevity Record: 20 Years and 4 months; based upon known age of
a wild Cooper's Hawk at
banding and subsequent band recovery (Data from Bird Banding Lab (Klimkiewicz
2008).
Migration: Cooper's Hawks migrate from the Northern parts of the
breeding range during late Autumn. There are many raptor migration sites where
they can be viewed during Migration.
Go to Raptor Migration Page
Coopers Hawk References
See Coopers Hawk Pictures,
with molt and ageing information
Go to Accipiters
Go to Sharp-shinned Hawk
Go to Northern Goshawk
Go to Buteos
Go to Falcons
Go to Bird Pictures Page
Go to Bird Watching Bliss Home
|
Questions or Comments?
Please Ask Your Question or Leave Your Comment Below: