Birds, humans look out for Cooper’s hawks

With a long tail and short, rounded wings, male Cooper’s hawks are smaller than crows.

Photo by Calibas, Wikimedia Comm

Last weekend, while looking for butterflies along a fire lane in the State Forest, I was surprised by a sudden halt in the bird songs that were providing the soundtrack for my stroll. A prairie warbler, which had been reciting its ascending buzz with the regularity of a clock, missed his cue; a chipping sparrow bit off his song in mid-trill.

This sort of thing makes birders look up. So I did. And as is supposed to happen at such moments, I found myself trading stares with a smallish hawk passing almost over my head. A long tail, and short, rounded wings marked this as a Cooper’s hawk; its modest size, clearly smaller than a crow, marked it as a male. Gripped in its feet, pulled snuggly against its belly like a football in a fullback’s hands, the hawk carried a small, gray item – probably a meadow vole, hardy unprecedented but not quite a typical prey item for a Cooper’s, since this woodland hawk specializes in catching birds.

The hawk, making good time on firm, steady wingbeats and clearly aiming for a nearby stand of evergreens, did not appear happy to see me. It instantly veered off course and rapidly climbed. In a few seconds, it was in full soar, wings out straight and tail fully fanned, perhaps 200 feet above me. It circled a couple times, then banked steeply and dove toward a point on the other side of the evergreens it had originally been flying to. I lost sight of it, and in a few minutes, the birds were singing again.

It was not hard to figure out what was going on, and indeed, this kind of thing happens quite often these days. A hawk making a bee-line with prey in its talons in early June is on its way back to a nest, on the way home from doing some shopping for its mate and offspring. The sudden change of direction by the hawk I observed was aimed at concealing the location of the nest. The steep climb and circling simply reflected the bird taking a good look around, making sure I was alone and that no other threats were in the area. And the sudden plunge was probably the start of a more discreet approach to the nest, through the back door. I was probably standing within 100 yards of so of an active Cooper’s hawk nest.

The relationship between humans and Cooper’s hawks has not been a happy one. The hawks, being optimized for bird-hunting, have a hard time passing up chickens. And farmers, not wanting to lose chickens, for many years responded by shooting the hawks. Sport gunning for these “undesirable” birds of prey also took a heavy toll. While never really close to extinction, in the early 20th century the Cooper’s hawk was largely erased as a breeding bird in well-settled areas in our region.

Legal protection, a regional decline in farming, and a better appreciation of wildlife has resulted in fewer Cooper’s hawks being shot, and the species has steadily rebounded in numbers over the past few decades. Long a staple of the fall hawk migration on the Vineyard, Cooper’s hawks began (or, more precisely, resumed) breeding on the Vineyard about 20 years ago. It’s hard to tell how many pairs nest here, because these birds travel widely in search of prey, and they do their best to be discreet when they have eggs or young. But based on how often and how widely I see this species during the breeding season, I’d put our current nesting population somewhere around 20 pairs, and I’m convinced the number is growing slowly but steadily.

While known to nest in a wide range of settings, Cooper’s hawks are said to have a special fondness for nesting in white pines, and on the Vineyard at least, I think they almost always nest in evergreens of some kind. Concealment is surely the reason. While adult Cooper’s hawks have little to fear from other predators, the relationship between crows and Cooper’s hawks is one of mutual detestation. Crows simply can’t see one of these hawks without harassing it; they’d eat the hawk’s eggs or nestlings if they got the chance, and by mobbing adult hawks whenever they see one, crows spoil the hunting and delay the return of adult hawks to the nest.

Cooper’s hawks remain a common fall migrant on the Vineyard, their numbers peaking in early October, with some birds lingering on the Island through most winters. The species is much less obvious, and probably less numerous, during spring migration. One puzzle is whether our nesting population migrates south, or, as with our red-tailed hawks, reflects a distinctive, sedentary population of a generally migratory bird.

In any case, the Cooper’s hawk appears well established as a breeding bird here, and the eerie silence as songbirds catch sight of an approaching Cooper’s hawk will be a common event for alert Vineyard naturalists for years to come. Don’t forget to look up.