Every fall during the months of September through November many thousands of raptors ascend over the treetops and fly southward for the winter. These normally secretive birds are obliged to expose themselves to observation in the process. Over a dozen species can be seen during these months, ranging in size from bald eagles to the tiny kestrel. 

Each species tends to migrate during a specific window of time, but the one that gets publicized in the media is the movement of a species called the broad-winged hawk. This common little woodland hawk, about the size of a crow, spends its summer perched under the tree canopy, watching for movement on the forest floor. However, come September, most of these birds prepare to migrate to as far away as the northern Amazon basin. 

From the 10th to the 23d of September, established hawkwatch sites are crowded with observers searching for rising ‘kettles’ of these birds, which sometimes number in the hundreds, circling upwards in columns of warm air, called ‘thermals.’ As the air rises, it cools, eventually losing its lifting power, at which point the birds ‘peel’ off the top of the column and glide southwestward until they find another thermal where they can repeat the process, all the way to Central and South America.

There are several established sites for hawkwatching in our area. Putney Mountain in southern Vermont is one; South Pack Monadnock is another. Some people hike to the top of Mt. Watatic where the lower eastern summit provides excellent views to the south and east. Mount Wachusett in Westminster is a long-established site, used by the Eastern Mass Hawkwatch, where dozens of observers crowd the observation deck each fall. It has the advantage of a road to the summit, as does South Pack. Hawkwatchers are a friendly and communicative group, always glad to welcome new visitors to the watch and to provide them with tips of identifying what they see. All you need at a minimum is a pair of binoculars and warm clothing; the windchill on an open summit can be surprisingly intense, even when it is warm elsewhere. 

The intensity of the hawk migration varies with the weather. The best conditions are a mostly sunny day with cool temperatures and wind from the north at 10mph give or take. Northwest winds are often the best of the best. A few clouds in the sky provide a focusing point for one’s eyes. Contrails also help in this regard. 

The Northfield Bird Club doesn’t schedule its own hawkwatch trips, mainly because optimal days can’t be anticipated, given the vagaries of weather. However, outside of the established sites, one can, on days when the wind is favorable, simply watch from any point with a lot of sky space to the north, especially along a ‘lead line’ like a north-south ridge or along a river such as the Connecticut.  Success is admittedly hit or miss, but persistence can lead to some thrilling observations. Good luck!