Cooper’s Hawk - A Fine But Fearsome SF Bay Area Raptor

August 6, 2007 on 12:43 am | In Daily Local Birder |

Greetings Birders!
Well, birding has been a bit on the quiet side since the heat of summer set in on us here in Sonoma County. Sure, the California Quail are still making their evening promenade through the cool grass, and some of our migratory visitors are still in evidence if you know where to look, but the the rapture of spring is past and the flurry of fall has yet to begin.

Just when we thought things had gotten sedate in the local birding world, we found ourselves face to face with a long-sought raptor - Cooper’s Hawk!

What a thrill to spot this awesome bird of prey, perched on a wire over Hwy 12 near the residential community of Oakmont, just east of Santa Rosa, CA. You can bet we pulled the car over fast, leapt out of our seats and rushed through a bunch of extremely painful starthistle nettles to zone our birding binoculars in on this fabulous fowl!

You will DEFINITELY know it’s not a Red-shouldered Hawk
In Sonoma County, our 2 most common hawks are the of the genus Buteo. These common fellows are the big Red-tailed Hawk, Buteo jamaicensis, and the Hallowe’en-colored Red-shouldered Hawk, Buteo lineatus. Most of the time when you see a hawk as you’re driving around Sonoma County, it’s going to be one of these two birds. Yet, Cooper’s Hawk, Accipiter cooperii, is also a year-round resident. Note that he’s not a Buteo. Cooper’s hawk is of the genus Accipiter…a whole different branch of the birds of prey! If you’re used to the Red-tails and Red-shoulders, Cooper’s Hawk will immediately stand out as a very different looking raptor to you. Let’s compare him to the Red-shouldered hawk here, just to illustrate how different the fieldmarks of the adult birds are.

Yes, both of these birds feature that beautiful rust coloration on the chest, but note how the orange color goes right over the Red-shouldered Hawk’s head and shoulders. By contrast, the distinctive slate-colored cap of the Cooper’s Hawk gives the bird’s head a much darker appearance.

Now compare the wings and tails of the two birds. I call the Red-shouldered Hawk Hallowe’en-colored because of how his checkered black-and-white feathers contrast with the orange. By contrast, the slate of the Cooper’s Hawk’s head continues all down the back of his neck, shoulders, wings and tail. There is a striping of two grey tones on his tail, but it is not nearly as pronounced as the black and white tail of the Red-shouldered Hawk.

The two birds are of comparable size, with the 17″ Red-shouldered being perhaps an inch or so larger than Cooper’s, on average. The shape of the birds is markedly different, however. The Red-shouldered hawk looks somewhat like a well-fed teddy bear. He is stocky and sturdy looking. When I saw the Cooper’s Hawk this week, I was immediately struck by what a slender overall shape he had. I’d never seen such a slim-looking raptor before. His amazingly long tail only adds to his streamlined appearance. The tail-length is something that really stands out about this interesting bird - no other local hawk has such a long one.

Both birds have bright yellow legs, but Cooper’s Hawk has glowing red eyes! Be sure to notice them when next you see this less common local raptor. Yet, even the major field marks of head color and wing/tail color are likely to be plenty to let you know you are spotting Cooper’s Hawk and not the regular old Red-shouldered.

Further field notes on Cooper’s Hawk
Birds of prey thrill me. They are exciting to me in a way that is different from the joy I feel over seeing a warbler or a wren. Their majesty and powerful flight are awesome to behold. Yet, all the same, I know I can only have this appreciation of local raptors because I am a human being. When Cooper’s Hawk left his perch on the electric wire and flew directly over our heads, I was aware of being very glad that I’m not a little songbird. Yes - I’m afraid that little birds are the mainstay of Cooper’s Hawk’s diet. In fact, backyard birders often spot their first Cooper’s Hawk next to the birdfeeder. Yikes! Nature’s ways aren’t always pretty and I confess to feeling sad about the fear small birds must feel when they sense the shadow of this enemy slipping toward them.

Once the Cooper’s hawk was out of sight on Hwy 12 this week, the air was suddenly filled with goldfinches, house finches and doves, all coming out of hiding, relieved to be okay. The world of birds is full of rather heart-thumping moments like these. You realize this, the longer you watch.

In addition to making appearances in suburban areas, Cooper’s Hawks tend to inhabit riverside and forrest terrain. They build bark-lined nests of sticks on a platform and 3-5 blue eggs are common. Immature birds are a combination of brown and white and harder to identify than the adults.

Keep your eyes on the skies. If you see that beautiful slate and orange combination in a long-tailed hawk, chances are it’s Cooper’s!