Full Species Account

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The Cooper’s Hawk (Accipiter cooperii) is in the Order Accipitriformes  (Secretary Bird, Osprey, hawks, old world vultures, and eagles) and Family Accipitridae (hawks, old world vultures, and eagles) (1, 2). Accipiter fossils date back to 30-50 million years ago (3).

The adult Cooper’s Hawk flaunts a bluish back and rufous-barred under parts, and bright red eyes under its black cap. The upper side which is blue-grey and the pale under side of the tail, display large black bands. The juvenile plumage version is an overall brown with streaked under parts, and bright yellow eyes under a brown cap. A medium size hawk, it is ~ 14-20” long with a 29-37” wingspan. Adult females ‘weigh-in’ from 400 to 600 grams (~ 12-24 ounces) as compared to the demure male that weighs 230-300 grams (~ 8-15 ounces). (3)

The Cooper’s Hawk’s smaller ‘cousin’ - the Sharp-shinned Hawk (Accipiter striatus) share similar plumages. The best identification features between these two species are that the Cooper’s Hawk is larger (although the female Sharp-shinned Hawk is similar in size to the male Cooper’s Hawk) and has a proportionately longer tail with a broader white tip. (3)

The Cooper’s Hawk prefers forests with dense canopy cover, but it will take advantage of a forest edge or clearing for hunting. With broad wings, long tails and keen vision, all designed for high speeds and agility, this hawk can outmaneuver its prey - small birds and mammals. Hunting strategies include a direct flight approach or a ‘still-hunt’ from a perch. This hawks hooked bill, powerful legs, and strong feet that carry sharp and curved claws provide the tools needed to capture its prey by either hunt strategy. Even with these attributes for hunting, success rate is only ~ 50% for mammals and ~20% for birds. Even though small prey is preferred a Cooper’s Hawk diet may include larger birds – even their smaller cousin, the Sharp-Shinned Hawk. Michael LaCombe observed a Common Raven (~ 21-26 “ long; 45-51” wingspan; ~ 1.5-4.4 pds) being pursued by a Cooper’s Hawk – near Brackett ponds. Was the hawk chasing the raven away from its nest or was it actually hunting this ‘heavy-weight' corvid? (3, 4)

Although the Cooper’s Hawk is named after the naturalist, William Cooper (one of the founders of New York Academy of Sciences), other names styled after its hunting habits are common: Chicken Hawks (the bane of chicken farmers), Big Blue Darter, Swift Hawk, striker, and more. (5)

The Cooper’s Hawk generally breeds from March to July. Usually on a sunny mid-morning day, the male performs his flight displays for the female – wings are positioned in a deep arc. A chase ensues and the male shows his expanded under tail coverts (feathers). He raises his wings above his back and then flies in a wide arc while flapping in a slow rhythm. After a short courtship, the male bows and nest building begins. (5)

Nest sites can be near a stream, or other open water, or a forest opening in either deciduous or evergreen trees 8-16 meters above the ground. The nest is compact – a broad and flat platform of sticks placed at the fork of the tree trunk and a limb. The cavity of the nest, where the eggs and chicks reside, is lined with bark, leaves and other greenery. After two weeks of nest building, four to five cobalt blue eggs are placed in nest and incubated by the female for 30-34 days. White-downed chicks then emerge from their eggs. In another 27-30 days these chicks will venture off their nest – becoming fledglings and learning how to hunt on their own. The longevity of this hawk is approximately 8 – 12 years. (3)

Cooper’s Hawks migrate from most of their most northern ranges (including Maine), but in some cases they may remain sedentary. The juveniles will leave their natal grounds before the adults. Female adults and juveniles leave before males. Migration occurs from late August through September to mid-October along ridges or coastlines. Migration destinies include southern Florida, the Gulf States, and Mexico. Males return to their breeding territories before females. (3)

By: Patty Wainright

Reviewed by: Sam Wainright, Michelle Brown, Marty

References:

1. D.W. Winkler, S.M. Billerman, I.J. Lovette. (2015). Bird Families of the World: An Invitation to the Spectacular Diversity of Birds. Lynx Edicions, Barcelona (pages: 102-201)

2. del Hoyo, J. and Collar, N.J. (2014). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions, Barcelona (pages 518-557).

3. del Hoyo, J., Elliott, A., and Sargatal, J. eds. (1992). Handbook of the Birds of the World. Vol. 2. Lynx Edicions, Barcelona (pages: 52,159, 161).

4. Sibley, D.A.  (2000). National Audubon Society: The Sibley Guide to Birds.  Alfred A. Knopf, Inc. NY (pages: 190-191).