The Cooper's Hawk (Accipiter
cooperii) is intermediate-in-size among the three accipiters that occur in
the Kittatinny-Shawangunk raptor corridor. Although more common than the larger
Northern Goshawk, they still are not particularly common raptor corridor birds.
Cooper's Hawks nest in the Kittatinny-Shawangunk raptor corridor in large
woodlots and woodlands. Their nest is a large structure made of twigs placed on
a tree limb near the trunk, or in the tree's crotch. The nest is lined with
hemlock, maple, or oak bark. Generally there are 4 or 5 pale sky blue or dirty
white eggs deposited, which are incubated for 35 to 36 days.
The diet of Cooper's Hawk in New York was very carefully studied by Heinz
Meng who discovered that prey consists largely of medium-size birds such as
European Starlings, Common Flickers, and Eastern Meadowlarks, plus small
mammals such as Red Squirrels and Eastern Chipmunks. Sometimes lizards,
amphibians, and large insects also are captured and eaten.
Cooper's Hawks are seen during most of the autumn hawk migration season, but
October is the month when the largest numbers of these birds are migrating.
They are among the most difficult-to-identify of the migratory raptors seen in
the corridor. One key Cooper's Hawk field mark is its
long tail, generally with a well-rounded tip. Like all the accipiters, its
flight style consists of a series of flaps and glides -- but slower than that
seen in migrating Sharp-shinned Hawks, and somewhat more rapid than used by
Northern Goshawks. The flight also tends to be more direct than that of the
Sharpie.
Adult Cooper's Hawk. Drawing
by Earl L. Poole.
The numbers of migrating Cooper's Hawks counted at autumn hawk migration
lookouts such as Bake Oven Knob, Pa.,
vary considerably from year to year (see graph). Perhaps 10- or 12-year
population cycles are reflected in the migration counts. However, it will be
well into the next century before enough annual autumn hawk count data are
gathered to confirm or reject that idea.
Meanwhile, during winter, Cooper's Hawks sometimes discover concentrations
of birds at backyard bird feeders. Raptors are exhibiting normal behavior by
capturing such vulnerable prey. Hence, people can learn about predation ecology
when they see a Cooper's Hawk capturing and eating a
small bird at a backyard feeding station.
Suggested Reading
Brett, James J.
1991 The Mountain and The Migration: A Guide to Hawk
Mountain. Second
Edition. Cornell University
Press, Ithaca, N. Y.
Broun, Maurice
1949 Hawks Aloft: The Story of Hawk
Mountain. Dodd, Mead Co., New
York, N.Y.
Heintzelman, Donald S.
1975 Autumn Hawk Flights: The Migrations in Eastern North America.
Rutgers University
Press, New Brunswick, N. J.
1979 Hawks and Owls of North America.
Universe Books, New York, N. Y.
1986 The Migrations of Hawks. Indiana University Press, Bloomington, Ind.
1990 The 1957-1989 Bake Oven Knob Pa.,
Autumn Hawk Migration Field Study: A 30 Year Review and Summary. American Hawkwatcher , 17: 1-16.
Meng, Heinz
1959 Food Habits of Nesting Cooper's Hawks and Goshawks in
New York and Pennsylvania. Wilson Bulletin , 71: 169-174.
Issued: May 1994. The Kittatinny Raptor Corridor
Educational Handbook . Copyright
© 1994 by Wildlife Information Center, Inc. All rights
reserved.