One of the fall migration’s great wonders is the en masse journey of broad-winged hawks from their summer nesting grounds in the eastern U.S. to their wintering grounds in southern Central and northern South America. Most raptors migrate alone or in small groups, but the broad-winged travels with flocks of its own kind that can number well into the thousands when conditions are favorable.Broad-winged hawks make their long journey with great efficiency. They ride the upward draft of thermal air currents, a process known as kettling,” gaining lift and altitude from the rising warmed air until its temperature drops to the point where the bird gets no more lift. Then it peels off the thermal, in a movement known as "streaming," in search of another thermal to repeat the practice again. In this way a broad-winged can cover as much as a hundred miles a day!
In the nearly three decades I have birded in New England I only have been on three hawkwatches, and those were not particularly successful. Only a few raptors were observed as a result of poor conditions and/or location. That’s why earlier this week I made good on a long held vow I would observe the broad-winged hawk migration in all its splendor by driving down to Pack Monadnock in Miller State Park in Peterborough. Of the three hawkwatch sites run by NH Audubon, also including Carter Hill Orchard in Concord and Little Round Top in Bristol, Pack Monadnock takes pride of place. Counts of broad-winged hawks during the hawk observation season running from the beginning of September to early November, have gone as high as nearly 11,000 individuals!
The observation site is accessed via a somewhat harrowing 1.5-mile auto road that leads up to the summit. From there it is a 100-yard walk out to the rocky viewing point that offers a broad vista to the west, north and east. On this particular day the view was excellent. To the northwest I could see Mt. Ascutney’s hulking profile. On the northern horizon were Cardigan and Kearsarge. Far to the northeast were the White Mountains dominated by Mt. Washington’s conical profile. There was a light, northwesterly breeze, and fluffy cumulus clouds dotting the sky, a sign of thermal activity, portending well for a good broad-winged viewing day.
When I arrived at 10:00 A.M., seven birders already were scanning the sky with spotting scopes and binoculars for any raptor movement. They had little to show for their efforts, the site steward reported, opining that conditions had not warmed enough to stimulate the thermal activity that would spur the hawks to move.
By 11:00 A.M. that situation began to change rapidly. The site steward reported he had a “kettle” of broad-wingeds in his scope, but too far out to be seen with binoculars. As the moments elapsed, the birds were reported moving closer. Suddenly someone called out that a kettle was directly overhead! With a bit of scanning, I was able to locate it and was awestruck by the site in my glasses of perhaps 80 broad-wingeds swirling and spiraling above.
By now the number of observers had swollen to about two dozen, and the level of excitement had grown with the crowd. Suddenly, it seemed the hawks were everywhere, and there was a near frenzy among the observers as they called out their sightings to one another. “Look over there!” “Wow, watch them streaming” “This is amazing!”
Truthfully, I could not locate all the different conglomerations being reported, and I don’t think I was alone in that regard. At high altitude, the birds are little more than specks, and it takes a good set of binoculars and sharp, experienced eyes to locate them.
At noon I had to call it a day perhaps having seen with certainty some 500 broad-wingeds. This was against a reported total day-to-date of more than 1500 individuals. The day’s final count came in at a very impressive 4100 with eight bald eagles and 17 osprey thrown in for good measure. However, that count's size paled by comparison to the more than 7,000 broad-wingeds observed last Sunday at Mt. Wachusett, an astounding figure.
Heading down the auto road, I chided myself for not seeing more of the action. On the other hand, it was by far the best raptor observing day I had ever had. The sight of those soaring, swirling birds is one that will always stay with me, and it certainly is one worth trying to replicate in the very near future.
Photo credit: The view looking north from Pack Monadnock Blake Allison/Lyme, NH