Brushing up on hawks

The afternoon was warm, and I was floating on my back in the lake to cool off, when a hawk flew across the cove. It was moving fast, and in the few seconds before it disappeared into the grove of trees on the point I was able to get only a quick impression of the general size and shape. From below, it was light in color, with a long tail and short wings, typical of the group of hawks known as accipiters. It might have been one of our year-round residents, but it reminded me that this is the time of year to be on the lookout for migrating hawks. Most hawks migrate through here from August through October, using wind and weather to speed their progress and save their energy. This is the season to pay attention to weather reports, looking for days with wind out of the northwest, and cold fronts coming down from Canada.

Migrating hawks follow ridgelines and mountain ranges, taking advantage of updrafts to give them lift. They also seek out thermals, invisible columns of warm air that form over surfaces such as paved roads, rock cliffs, and any other places that catch the sun’s heat. Once inside the thermal, the hawk spreads it wings and spirals upward in the rising air. At the top of the thermal, the bird pulls its wings back and peels off, gliding effortlessly. It then looks for another thermal, and repeats the process. In spring and fall, hawk watchers gather on mountaintops to watch migrating hawks. Hawk Mountain in South Waterford, and other mountains with exposed rock are good places, as are Bradbury Mountain in Bradbury Mountain State Park, and Mount Agamenticus in York County. On some mountains, such as Cadillac, in Acadia National Park, the Hawk Migration Association of North America conducts official migration counts.

Hawk migration is one of the marvels of the natural world, but to enjoy it best it helps to know what to look for. The hardest part for beginners is learning how tell a hawk from a non-hawk, such as a crow, raven, or turkey vulture. It also helps to recognize bald eagles, northern harriers, and osprey. Each has a distinct appearance in the air, so once familiar with those birds it is easier to move on to learning the groups of hawks known as accipiters, buteos, and falcons.

Accipiters are birds of the forest who hunt with speed and agility, and whose relatively short wings and long tails enable them to maneuver quickly and steer in tight spaces. Three species of accipiters live year round in Maine. The northern goshawk, larger than a crow, can take prey as large as a ruffed grouse or a snowshoe hare. The Cooper’s hawk and the sharp-shinned hawk are very similar in appearance, but the sharp-shinned is smaller. About the size of a blue jay, the sharp-shinned typically flies with several quick flaps followed by a short glide, described as flap-flap-sail.

Buteos have broad wings and relatively shorter tails, and large numbers of them can be seen soaring in circles as they rise up in thermals. Pete Dunne, co-author with David Sibley and Clay Sutton of the classic Hawks In Flight, calls buteos the “clipper ships of the sky,” and “keen-eyed wind masters, able to tease lift from temperature-troubled air and to soar for long periods on set wings.” The red-tailed, red-shouldered, broad-winged, and rough-legged hawks are the buteos found in Maine. A good field guide, and good viewing conditions, make identification of these birds much easier.

Another group of hawks, the falcons, are extremely fast, powerful fliers with slender pointed wings. The four falcons seen in Maine, American kestrel, merlin, peregrine falcon, and gyrfalcon, are long distance migrants. Most falcons take bird prey on the wing, in high-speed chases, but the kestrel, the smallest falcon, hunts its prey, typically mice, on the ground.

The bird flying overhead while I floated on my back in the lake was an accipiter. I was not able to tell if it was a sharp-shinned or Cooper’s hawk because the plumage of these two species is very similar and the relative size is difficult to judge. The Cooper’s is larger, but identification is complicated by the fact that female hawks are larger than males, so there may be little difference in size between a large female sharp-shinned hawk and a small male Cooper’s. I wondered if the hawk, who probably was hoping to catch a songbird for lunch, was our local resident or an early migrant. In any case, I had at least recognized it as a hawk, and beyond that as an accipiter. It was a good reminder that this is the time of year to watch for northwest winds, keep an eye on the sky, and brush up on hawk identification skills.

Jean Preis resides in Bridgton.

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