COOPER'S HAWK
Accipiter cooperii

    The beautiful and baleful Cooper's hawk is an accipiter, one of three related species found in the U.S. that share many traits. Like the smaller sharp-shinned hawk and the much larger goshawk, the Cooper's hawk is classified by ornithologists as belonging to the genus Accipiter. Worldwide there are approximately 50 species in the genus. North America is home to the three species mentioned above. Accipiters are characterized by relatively short, rounded wings, a long, rudderlike tail and long legs. The females are noticeably larger than the males. Accipiters are forest hawks, adapted for speed and agility in maneuvering through branches and brush. Their flight pattern is distinctive, consisting of several steady wingbeats (usually five) followed by a glide, then another series of wingbeats followed by another glide. Accipiters often prey on other birds, and these hawks are nimble enough to catch prey in the air. Their food and habitat preference are reflected in their build. Accipiters have shortish, rounded wings that can produce an instant burst of speed when prey is spotted. The long tail serves as rudder and brake to steer the hawks around or through dense vegetation. And the long legs are used to pull prey from cover, for if their quarry seeks shelter on the ground, accipiters won't hesitate to hunt it down on foot. Because of their preference for forested habitat, accipiters are rarely seen except during migration.

      Like the sharp-shinned hawk and the goshawk, the Cooper's hawk early in this country's history acquired an unfortunate reputation for killing chickens. While this tendency has been exaggerated, it's certainly true that Cooper's hawks did take some chickens. It should also be said that settlers exterminated the passenger pigeon, once present in the East in such large numbers that colonists spoke of flocks that darkened the sky. With this once-abundant prey species wiped out, and free-ranging chickens easy pickings, the opportunistic Cooper's hawk did sometimes raid the farmyard. Another characteristic of this hawk that did not endear it to settlers was its liking for game birds such as bobwhite and ruffed grouse. That put the Cooper's hawk into competition with human hunters, who felt that they and not some hawk should be eating the quail and grouse. The Cooper's hawk acquired uncomplimentary names such as "chicken hawk," "quail hawk" and "partridge hawk" and was usually shot on sight - when it was seen. Another old name for this blue-gray hawk is "big blue darter" (the smaller sharp-shinned hawk was dubbed the "little blue darter") because of its uncanny ability to dart in, snatch up an unwary victim and be gone in seconds.

      This hawk's present-day name comes from American zoologist William Cooper (1798? - 1864). He collected a hawk that was thought to be a new species, and Charles Lucien Bonaparte, author of American Ornithology, named the bird in Cooper's honor. The Cooper's hawk is approximately crow-sized, but males are much smaller than females. Males average 15 inches in length, with an average weight of 12 ounces. Wingspan averages 29 inches across. Females average 18 inches in length, with an average weight of 19 ounces. Wingspan averages 33 inches across. Although significantly smaller than the females, male Cooper's hawks are never as small as the jay-sized sharp-shinned hawk. Nor do Cooper's hawks have the extremely thin legs of the sharpie. The Cooper's is an exquisitely proportioned bird, a dark slate to steel-blue above at maturity (females have a brown cast to their feathers). The crown is black and the nape whitish. The underparts are creamy-white, marked with wide bands of reddish brown. The long tail bears three dark bands. The eyes of the adult birds are vivid, orange that deepens to red in two or three years. First-year birds are uniformly brown above and streaked with brown below. Their eyes are pale amber or yellow.

      The Cooper's hawk breeds from central Canada to central Mexico. It is found throughout most of the U.S. with the exception of the northern Great Plains and the lower half of Florida. The species winters from the northern tier of the U.S. to Central and (sometimes) South America. Because the Cooper's hawk's distribution is more southern than that of the sharp-shinned hawk, the Northeast does not see the large numbers of migrating Cooper's hawks that it does of sharp-shins. Cooper's hawks migrate after the sharp-shins have peaked and before goshawks put in an appearance. The migration period for the Cooper's begins around the third week in September and continues through October and into November. Spring migration is later than that of the other accipiters; Cooper's hawks may not return to the Northeast until April or May. During migration this hawk soars frequently, fanning its long tail as it does so. Then birdwatchers can clearly see the wide band of white at the tip of the tail that helps to identify a Cooper's hawk. Sharp-shinned hawks, by contrast, have a narrow white band at the tail tip. For more on identifying the Cooper's hawk in flight or in the field, see Hawks of North America and A Photographic Guide to North American Raptors, both by William Clark and Brian Wheeler; or The Sibley Guide to Birds by David Allen Sibley.

      This hawk prefers a less dense forest environment that the sharp-shinned hawk, choosing to live in woodland among older, full-sized trees that prevent undergrowth. The Cooper's also seems to need larger areas of undisturbed forest than the sharpie. In its woodland habitat this is a specialized bird-hunter. In the East, about 80% of the Cooper's food is small to medium birds. In addition to game birds like the bobwhite, frequent targets are sparrows, starlings, grackles, flickers, blue-jays, meadowlarks and robins. The Eastern birds also take a fair number of chipmunks and red squirrels. Still-hunting (sitting on a perch and watching for the movement of prey) is a favorite Cooper's hawk technique. So is flying low to the ground, either to ambush prey or to scare it out of cover. Hunting on foot is also a Cooper's technique, and this species has been observed using its hearing to locate hidden prey. It will then use its long legs and toes to snatch a luckless victim from cover. In common with the sharp-shinned hawk and the goshawk, the Cooper's hawk carries its prey to a favorite "plucking post." This is a branch or log where the hawk plucks off feathers or fur before eating.

      In the less populated West, where Cooper's hawks are somewhat smaller than the Eastern birds, this species eats far more mammals. It also expands the menu to include reptiles like lizards. Western birds differ in behavior as well. Perhaps because they are less familiar with people than the Eastern birds, Western Cooper's hawks are bolder, more apt to perch in the open.

      Cooper's hawk nests are in mature stands of trees, usually near a clearing and often near water. In Massachusetts Cooper's often nest in white pine stands, but beech, maple and hickory may also be chosen. The stick nest is usually constructed near the trunk of the tree, and fresh evergreen sprigs are placed inside. Usually a new nest is built each spring. Four or five eggs are laid in April or May and are incubated for 30 to 32 days. The young are on the wing a month later. Or at least the males are. Males take 30 days to fledge (reach the flying stage); the larger, more slowly-developing females take 34 days. Both sexes begin hunting for themselves when they're about two months old. In the West, Cooper's hawks will defend their nests, but in the East, where the birds have been dealing with human persecution for generations, the hawks have become more secretive. Cooper's hawks will abandon their nests if they are disturbed during incubation.

      While Cooper's hawks are more numerous in the West, this is not a common species anywhere in the U.S. Back in the 1970s it became evident that the Eastern birds were in significant decline. The reason or reasons is unclear, but one factor certainly was pesticide poisoning. The main culprit was DDT, and its use in the U.S. was banned in 1972. Since then the Cooper's seems to be on the increase, and now this hawk is being seen in greater numbers during fall migration (during spring migration this species is much more difficult to find). Confirmed nesting records are still sparse in the Northeast, however. In Massachusetts the Cooper's hawk is regarded as a rare breeding bird. In the past decade only a few nests have been discovered. Connecticut recorded nine nesting pair in 1988; in the same year Massachusetts recorded one confirmed nest. So this hawk is still a rarity in our area, even though its numbers do seem to be modestly increasing. One possible reason is that many of our farms are reverting back to woodland, presenting the Cooper's with its favorite habitat - forest broken by clearings. Since it seems to favor mature forest, perhaps the Cooper's hawk's reappearance is tied to ecological succession.


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