What birds are visiting your feeders? Probably cardinals and jays and chickadees and juncos and doves and the usual winter mix that comes to partake of seeds and suet. What do all these birds have in common? They attract what many people consider uninvited guests -- the bird hawks, members of the genus Accipiter, a word that comes from the Latin verb meaning "to seize." I know one is around our yard when the feeder birds become very still or suddenly disappear. Hawks are a natural part of the web of life and they help keep everything in balance. I'd prefer they catch starlings and house sparrows, but it seldom seems to work that way.
In much of the United States, from Washington to Iowa to Massachusetts and south, there are two Accipiter species likely to visit your yard in winter, the Sharp-shinned (Accipiter striatus) and the Cooper's Hawk (A. cooperii), but they are difficult at best to separate. Male Sharp-shinned Hawks are about 11 inches long, roughly the size of a blue jay. Like most hawks, the females are significantly larger. Female sharpie's are 14 inches long, about the size of a pigeon, but slimmer. Here's the problem. Male Cooper's Hawks are about the same size as female sharpie's and maybe an inch longer. The larger female Cooper's is approximately the size of a crow.
|An adult Sharp-shinned Hawk eating what might have been a Mourning Dove |
(judging by the color of the feathers on the snow after the hawk left - but its hard to tell).
Plumages of our two bird hawks are virtually identical, making it that much harder to tell one from the other. Juveniles of both are brown on top and streaked lengthwise underneath. Juvenile Cooper's have thinner, darker, tear-drop-shaped streaks, but that is subjective and requires some experience for comparison. The juvenile's yellow eyes turn orange and then red as Accipiters mature. Adults are gray or blue-gray on top, hence the nickname "blue darter." The cap or crown is darker like charcoal, especially on Cooper's. (Sometimes a Cooper's Hawk will raise its hackles giving it a small crest.) Sharpie's have more of a hood, meaning the dark crown extends down the nape, wheras Cooper's have a lighter nape.
Underneath, adults of both species are light colored with rufous cross barring on the chest giving way to white under the tail. At all ages, the tail is coarsely barred with dark bands. Under ideal conditions, subtle differences in the tail can be discerned. Sharp-shins have a square or notched tip on a slightly narrower tail. Cooper's tails are slightly wider or fanned with rounded ends due to the outer tail feathers being shorter than the inner ones (but molting could confuse the issue). A white tail tip is more noticeable on Cooper's, but this can be masked by feather wear. Cooper's have white bellies whereas sharpie's tend to have more smudged or "dirty" bellies (another subjective call).
|juvie Cooper's again showing a slight crest and making the eye appear closer to the front|
(by comparison, Sharpie's eyes appear larger and more centered on the head)
The third and largest member of the Accipiters, the Northern Goshawk (Accipiter gentilis) is a bird of Canada, the north woods and the Rockies. The name "goshawk" comes from the Old English word goshafoc, meaning "goose hawk." I have no photos of this species, but a distinguishing characteristic is a light line (called a supercilium) above the eye. This line is white in adults and it contrasts with a dark line through the eye. Adults are also gray on the back and light gray on the belly, but never rufous like the smaller bird-hawk adults. Juvenile goshawks are brown and streaky and have pale-tipped greater coverts overlapping the inner (secondary) wing flight feathers.
All of these raptors have relatively short wings for maneuvering between woodland trees. The small sharp-shin can even adeptly chase prey through bushes. I watched as one hunted chickadees. It was an aerial acrobat making contorted maneuvers, weaving and diving through the sumac and other shrubs in hot pursuit of black-caps. Accipiters have long tails to aid in sudden, sharp turns. Although small birds are the staple diet of our Accipiters, they will take other prey. Sharpie's will take mammals up to Red Squirrel size; Cooper's up to Gray Squirrel.
|adult Sharp-shin again, showing square corners on the tail and a small, rounded head|
with the crown extending down the back of the head and forming a "hood"
Mouse- and insect-eating hawks like the kestrel and redtail perch in the open and watch the ground for signs of motion. Accipiters prefer to hide in a tree or bush while they eye your feeder. When they attack, their flight is swift and low. From the side, sharp-shins appear "neckless;" they keep their heads pulled in and wings pushed forward, compressing their short necks. Overhead, this gives them a "T" shape. Cooper's have longer necks and larger heads, and overhead have the appearance of a cross. During migration, sharpie's will intersperse bursts of rapid flapping with glides and they may circle briefly if they encounter a thermal (an updraft). Cooper's flight is more direct and determined.
To the birds at your feeder, it makes no difference what species is chasing them. It's strictly a matter of life or death. The faster birds survive; the slower stragglers (read "old, sick or injured") don't. Remember the old saying, "Survival of the fittest?" If you want to help your seed eaters survive, locate your feeder(s) close to escape cover. The denser the better... Discarded Christmas trees can be staked next to the feeder and also serve as a wind break. (You also might consider placing a baffle or skirt around the bottom of the tree to prevent cats from hiding underneath.) In my younger days, when I had fewer back problems, we bought a live Christmas tree every year and planted it in the spring. Some of those trees are pretty big now and several of our feeders hang from the inner branches. If your zoning regulations permit, a loose brush pile also provides escape cover and winter storm protection for birds and small mammals. At least the House Sparrows will appreciate it and roost there overnight. Our Carolina Wren also uses the brush pile -- when it's not in the thicket across the road.
Okay, look out the window again at your feeder. Now, what do you see?
For more information, photos and sounds, visit the All About Birds website and type in the species of interest. An interactive range map (zoomable to your location) can be found in the eBird Explore Data section. Again, type in the species.
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