Cooper's hawk or peregrine falcon? How you can tell

 
By Mark Spreyer
Executive Director, Stillman Nature Center, South Barrington
Posted2/19/2018 11:42 AM
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  • Adult Cooper's Hawk with prey.

    Adult Cooper's Hawk with prey. Courtesy of Kristi Overgaard

Editor's note: This is the first in a series of contributions from naturalist and author Mark Spreyer. Spreyer did his graduate work in Minnesota on great gray owls and then went on to organize and direct Chicago's peregrine falcon release program. Under his leadership, Chicago hosted the first nest of peregrines in Illinois in 37 years. In 1989, he returned to Minnesota, where he worked with the Minnesota National Wildlife Refuge and other conservation organizations. In 1995, after completing work on a raptor exhibit with the Science Museum of Minnesota, Spreyer migrated back to Illinois to become Executive Director of the Stillman Nature Center. During his career, Spreyer has also worked with the Brooklyn Botanic Garden, National Audubon Society, and Chicago Academy of Sciences and has taught courses for the College of Lake County and Northeastern Illinois University. His recent book of nature essays, "Natural Digressions," covers everything from wildflowers to owls, with a heaping dose of humor.

I sometimes get calls about a bird-eating "peregrine falcon" in a suburban yard. In almost every instance, the caller has misidentified a Cooper's Hawk (Accipiter cooperii) as a peregrine.

The Cooper's Hawk is one of North America's accipiters. Accipiters have short wings and long tails that act like rudders. This design facilitates zigzag pursuits of prey, mainly birds and small mammals, through wooded habitats.

The Cooper's Hawk is about the size of a crow. It has blue-gray upper parts, a blackish crown, reddish breast, rounded tail, yellow legs, and piercing eyes that change from yellow to a deep ruby red as the bird ages.

Opportunistic Cooper's hawks will prey upon robins, mourning doves, jays, flickers, starlings, mice, and chipmunks.

It was not so long ago that watching a Cooper's Hawk hunt would have been extremely rare. The Cooper's Hawk had been on the state's endangered species list for many years. It wasn't only rare in Illinois.

Continental populations of the Cooper's Hawk declined rapidly during the 1960s and 1970s, primarily because of pesticides, particularly DDT. Once the use of this pesticide was banned, the Cooper's Hawk began its dramatic recovery.

In 1981, this species was known to breed in only four Illinois counties. By 1992, the number had grown to 21 counties. In 1996, due to significant increases in the breeding population, this hawk was removed from the Illinois Endangered and Threatened Species List.

The breeding population is highest in the northern and southern reaches of Illinois, where nests are found in forested areas. It lays two to five eggs, which are all white or white with brownish markings.

Many a suburban feeding station, from Arlington Heights to Alsip, has been visited by an enterprising Cooper's Hawk. Of course, they aren't feeding on seed, but on the seed eaters.

If you enjoy feeding birds near your house, I bet this has happened to you. You look out the window and see cardinals, juncos, and chickadees diligently pecking at seed in your feeders. You turn away to take care of some household chore. When you look back, all the birds are gone. Take it from me, a Cooper's Hawk has just arrived in your yard.

Don't despair, the smaller birds will return. Cooper's hawks and songbirds have been doing this predatory dance through the ages. I'm just glad that this one-time rarity has become a backyard commodity.

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