Wild Side: American kestrel

This attractive hawk has been feeding at Katama Farm.

A male American kestrel, similar to this one photographed at Raptor, Inc., in Ohio, has been in residence at Katama since October. — Greg Hume

While snowy owls and a remarkable invasion of finch species have dominated the attention of birders over the past few months, an attractive and interesting bird has quietly set up shop in Edgartown, amid the vast pastures of Katama Farm. An elegant male American kestrel, the smallest and arguably the prettiest of our hawks, has been putting on reliable performances for months now.

The bird may have arrived as early as Oct. 11, when Lanny McDowell reported a kestrel perched on a Katama farm silo. But certainly by the end of October the same bird that is there now was being reported regularly, most often from the fence lines along the dirt road that crosses the largest pasture at the farm.

In a sense, what’s most notable about this bird is that it’s notable. Not that many years ago, the American kestrel was a common bird on the Vineyard and indeed throughout the region. As a young birder bicycling around Boston’s western suburbs 50 years ago, I expected to see a few kestrels almost every time I was in the field, the birds either hovering over fields or perched on wires, often where high-tension powerline cuts crossed roads. And through the first three-quarters of the 20th century, kestrels were common migrants and fairly common breeding birds on Martha’s Vineyard.

Since those halcyon days for the species, though, kestrels have steadily declined both as breeding birds and as migrants in Southern New England. The decline is presumed to have been driven by the twin forces of reforestation (as abandoned farmland grows up into woodland that offers little to kestrels) and suburbanization (which results in fragmented habitat that, again, these tiny falcons have little use for). In any event, the decline has been dramatic, and a similar decline has occurred (for similar reasons) in much of the Northeast.

“On Cape Cod and the Islands,” notes Massachusetts Audubon’s Breeding Bird Atlas 2, “the species teeters perilously close to regional extirpation as a breeding species.” Kestrels do still occur here regularly as migrants; on a good day during fall migration, you might encounter four or five around the Island (the Gay Head Cliffs are the best place to look). Even in spring, when raptor migration tends to bypass the Vineyard, single kestrels are often reported (the grassland at Wasque Point is a favored location in spring). Lingering kestrels turn up with some regularity on the Vineyard Christmas Bird Count, and birds remaining deep into or even all the way through the winter are sometimes noted. But the current Katama bird has been remarkable for its fidelity to its preferred location and the ease with which it can be observed.

Kestrels of both sexes present as small falcons, long-tailed and with pointed wings. Both sexes show a strong black stripe on the side of the face. Males, like our bird, are smaller than females (this is typical among hawks) and show gray wings and a dark tail tip. A female kestrel would appear browner overall and show extensive black barring on her back and tail. These are pretty birds. In flight, kestrels seem less powerful than other falcons, more given to circling and soaring. They are capable of prolonged hovering, a talent they use when lining up a potential target for a swooping attack.

The main attraction at Katama Farm is presumably the robust population of meadow voles. These succulent, mouse-sized rodents are a favored prey of many predators, and kestrels, which typically hunt either from perches or in low, rambling flight over promising habitat, are well equipped for harvesting them. The farm’s pastures also feature large numbers of overwintering grasshopper nymphs, and since invertebrates make up a large portion of this small falcon’s diet, the bird may be nabbing some of them, as well.

On Jan. 20, ace bird photographer Jeff Bernier shot a remarkable series of photos showing the kestrel chasing away a Northern harrier at Katama Farm. As Jeff’s Facebook post noted, the harrier is a much larger bird. The boldness of the kestrel, clearly the result of a territorial impulse, may simply reflect that the bird has been present long enough to have developed a sense of ownership of the site. But it may also reflect a decline in prey density. In addition to the kestrel and harriers, a couple of highly competent red-tailed hawks work those fields, and a reduced abundance of voles may be forcing the kestrel to be more protective of its resources.

How much longer will this bird remain? That probably depends on how the vole supply holds out and how the winter develops. Already present for more than three months, the bird appears to be receptive to the notion of spending the whole winter in Edgartown. But adverse weather — either prolonged cold or significant snow cover, which would make the vole hunting a lot more difficult — may oblige the bird to move. Sooner rather than later might be the best time to look for it.