Words On Birds by Steve Grinley
Autumn Brings Migrating Hawks To Area
September 18, 2010
by Steve Grinley
September and October are prime months for the fall hawk migration, so I thought you may want to read again about the different species of hawks that you might see:
As the midday sun warms the earth on cool autumn days, the warm air rises into thermals on which hawks use to glide their way south. River valleys and mountain ridges provide thermal paths along which hawks migrate. In this area, the Merrimack Valley provides good thermals for migrating raptors. Behind the Page School in West Newbury is one of the more popular spots for hawk watchers in this area. It provides a panoramic view of the Merrimack Valley and you can watch hawks as they approach from the north. Old Town Hill in Newbury is another vantage point, or you may find your own favorite knoll to view the hawk flight. Within an hour or so drive are Mount Wachusett and Mount Watatic in central Massachusetts and Mount Agamenticus in southern Maine. These are popular spots where hawk watching vigils are held.
Identifying hawks can be difficult, even for experienced birders. Plumage differences between males and females and among juveniles give the most experienced hawk watchers problems. A good spotting scope helps distinguish field marks when birds are soaring at great heights. However, a good pair of binoculars and sometimes even the naked eye can distinguish many hawk species.
Most hawks can be identified into one of three groups: buteos, accipiters and falcons. Buteos are large hawks with broad wings and short rounded tails. Accipiters are generally smaller than buteos with rounded wings and long tails. Falcons have pointed wings and long tails.
The red-tailed hawk is probably the most familiar buteo. They are the common roadside hawk that you see sitting in a tree along Routes 95 or 495. They have a white chest with a dark band across the belly. Its red tail is present in adult birds, but juvenile red-tails have brown tails. If counting migrating hawks, you have to make sure that any red-tails you see are migrants and not just the local “residents” wandering back and forth across your view.
The most plentiful of the migrating buteos in the east is the broad-winged hawk. Broad-wings are somewhat smaller that red-tails with wide light and dark bands across the tail. Broadwings migrates by the thousands through Massachusetts and sometimes kettles of several hundred can be spotted on a good autumn day. Red-shouldered hawks and the larger rough-legged hawk are less numerous but often make appearances among the other buteos.
Of the three common accipiters, the smallest in migration is the sharp-shinned hawk. The wing beat pattern of “flap, flap, sail” is characteristic of accipiters (though other hawks do that occasionally too). The Cooper’s and sharp-shinned hawks are nearly identical in color patterns with the sharpy usually the smaller of the two with a square tail. The rounded tail of the cooper’s hawk helps distinguish it. Female hawks are usually larger than males so a female sharp-shinned can be as large as a male Cooper’s, making identification tricky. The goshawk is the largest accipiter, crow size, and appears very light underneath.
Of the three eastern falcons the largest and fastest is the peregrine falcon which can reach speeds in excess of 60 mph with a strong tail wind or when diving for a duck or pigeon. The American kestrel is the most plentiful of the falcons during migration. Adult kestrels are identified by their small size, rusty coloration on their back and tail and light color underneath. Both the peregrine and the kestrel sport black sideburns. The merlin is small like the kestrel but striped underneath with a noticeable white tip to the tail and a white line over the eye.
Several large migrating raptors don’t fall into these three groups. Harriers, once called marsh hawks, have long wings and tail and a white rump patch. The large turkey vulture, which is increasing in numbers in the northeast, has a long tail and dark two tone wings held in a dihedral. Another large raptor, the osprey, soars with a “crook” in the wing and its strong white and brown coloration is distinctive. During this fall migration, you may be lucky enough to catch sight of our national symbol, a bald eagle, soaring on flat wings with slightly upturned “fingers” at their wing tips as they glide overhead.
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