Caption: This adult Cooper’s Hawk has successfully captured a White-winged Dove.
by Bob Walker
The Cooper’s Hawk (Accipiter cooperii) is our other common back-yard bird of prey in Los Alamos County. It very closely resembles the slightly smaller Sharp-shinned Hawk, both in plumage and behavior. It can be found in Los Alamos County all year long, with little or no seasonal variation in frequency of reports. It is seen slightly more often than the Sharp-shinned Hawk. These two hawks can be very difficult to tell apart, and when you see one and are not sure which species it is, you will be in good company with many expert birdwatchers. The main field marks I have heard local birdwatchers use is; (1) the bird’s size, Cooper’s Hawks are crow-sized, Sharp-shinned Hawks are more the size of a dove; (2) the appearance of the head, Cooper’s Hawks have slightly larger, flatter shaped heads and adults are darker on top, Sharp-shinned Hawks heads are more rounded, golf-ball-like; and if visible (3) the shape of the tails, Cooper’s Hawks have more rounded tails, while Sharp-shinned Hawks have tails that are more square.
Cooper’s Hawks have often been seen on nests in Los Alamos County, raising two to five chicks. The young birds show a different plumage pattern on their front side – brownish teardrop-shaped streaks instead of the finely horizontally-barred orange feathers of adults.
Find more detailed articles about Cooper’s Hawks on these web pages: identify.whatbird.com and allaboutbirds.org. There is a good web page with many Cooper’s vs. Sharp-shinned ID tips at Cornell Lab’s feederwatch.org. You can see beautiful photos of adult and juvenile Cooper’s Hawks at the Brian Small web site. For more images, perform an image search on Google or Flickr, and you’ll see many good photographs.