Illinois Natural History Survey - University of Illinois

Cooper's
Hawk

 

Susan Post

 

"[The cooper’s hawk] had become a brown-cloaked, streak-breasted torpedo, weaving through a world of shadows."  

Pete Dunne   

The Wind Masters 

 

The Cooper’s Hawk, Accipiter cooperii, was named after the naturalist William Cooper, one of the founders of the New York Academy of Sciences. Common names include Big Blue Darter, Bullet Hawk, Swift Hawk, Black-capped Hawk, Striker, Chicken Hawk, Hen Hawk, Quail Hawk, Partridge Hawk, and Pigeon Hawk. Some of these names are based on physical characteristics of the bird, while other names refer to hunting tactics or prey. It is for the latter [prey items] that early settlers persecuted these hawks.

Cooper’s Hawks belong to the genus Accipiter, a group of birds adapted for short bursts of weaving flight through heavy brush to capture their prey in deep woods and thick undergrowth. Surprise is the ally of an accipiter, not endurance. Think of these birds as sprinters or like cheetahs. If the prey is not taken in the first attempt or after a short chase, pursuit is broken off.  There birds hunt by stealth, listening and watching, approaching their prey through dense cover, and then pouncing with rapid powerful flight

In the United States there are three members of the genus Accipiter—Sharp-shinned Hawk, Cooper's Hawk, and Goshawk. Distinguishing one from the other is not easy. Cooper’s Hawks are lanky, with long, straight tails with dark bands ending with white terminal bands. Their tails have round tips. The adults are slate blue above with orangish breasts. They have dark caps and red eyes. Juveniles are clean breasted and have a dark, hooded appearance. They have yellow eyes and are warm brown in color. In flight Cooper’s Hawks appear long-necked and they look like flying crucifixes or Roman crosses.

 The hawk’s victims are almost always birds that vary in size from wood warblers to Pheasants. While they will pursue warblers or chickadees, they favor larger prey, birds up to the size of Pheasants and mammals as large as squirrels. Cooper’s Hawks need robin-sized meals daily, and in energy requirements it takes less time and energy to capture one robin-sized bird than six warbler-sized birds.

They capture their prey with their feet and kill them by repeated squeezing their talons. Cooper’s Hawks hold their catch away from the body until it dies.

The Cooper’s Hawk nest, a bulky structure of sticks lined with bark, is in a tree and is usually 25 to 50 feet above ground. Many times the nest will be on top of an abandoned squirrel nest. Three to five pale bluish white eggs are laid. Incubation lasts 34 to 36 days. During this time the male will bring food to the female. Once the eggs hatch, both parents feed the hungry chicks, which will be able to fly in about four to five weeks.

Cooper’s Hawks may be found in a variety of forest and woodland habitats—open woodlands, mature forest, wood edges, and river groves. They have even adapted to our backyard bird feeders. Perching in trees overlooking the feeder, they swoop down and scatter the other birds in order to capture one in flight.

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