By David Spector Gazette Contributing Writer
The science of ecology often entails studying the distribution and abundance of species: Why are they where they are, and what determines their population size? On a single day of bird watching, I had the opportunity to observe two species whose presence and numbers led to very different answers to these questions, even as their lives intersected.
A year ago, I took a drive through some farm fields in Hadley, which provide habitat for open-country species of birds. These include both breeding birds and those that come down from farther north to spend the winter here. That day I saw a flock of a dozen horned larks. These plump little birds, with distinctive bold facial markings and tufts of feathers forming little “horns” at the corners of the face, make pleasingly comical sights from the human perspective. In flight they present a more serious image, flocks of sleek birds swarming over the land.
The horned lark is the only member of the lark family native to the Americas, although there are some 96 species in the Old World. The breeding population of this species is quite small in western Massachusetts, but the birds’ numbers swell during migration and in winter when locals are joined by many more that breed on the Arctic tundra.
As I left the fields, I stopped the car to take one last scan for birds, and I noticed what looked like a large ash falling from the sky. I was concerned that a fire might be breaking out nearby until I took a closer look and realized that the “ash” was a feather, one of several drifting down around my car. I looked up and saw, atop a nearby utility pole, a horned lark being plucked by a merlin, a small bird-eating falcon.
The merlin hunts birds in the air, and is known to hawk-watchers as the “bullet hawk” for its fast, direct flight. It might not be coincidental that I saw the lark becoming a meal. Merlins have been seen hunting in the company of large mammals or vehicles and preying on birds flushed into flight. The merlin I saw may well have followed my car, using it both as cover and as a beater to put prey into the air.
A few decades ago, merlins were uncommon migrants here, shooting through between their northern breeding grounds and their more southern wintering range. Recently, though, a few merlins have wintered in the Connecticut Valley as the species’ winter range has expanded north. Also, merlins are breeding more to the south than previously known, and last year the first breeding record for the species in western Massachusetts was reported in Northampton. In the Canadian part of the merlin’s range, the falcon has now moved beyond the classic wilderness and started nesting in cities.
So why are merlins expanding their range and habitat in these ways? The reasons may be many, but at least one is related to human activity: the spread of fruit-bearing plants, including invasive plants like oriental bittersweet and deliberately planted ornamentals like crabapples and cherries. These have supported expanding populations of fruit-eating birds like robins and waxwings that in turn provide prey for the merlins.
Another question, yet to be answered: Will the nesting population of merlins become established and expand in western Massachusetts? We have two habitats the bird finds suitable. The far northwest corner of our state offers patches of boreal (spruce/fir) habitat similar to the classic northern wilderness breeding areas of the species, and places like Northampton provide an urban environment that matches the merlins’ more recent choices. Only time will tell whether these are sufficient to support an ongoing presence of these falcons in our midst.
David Spector is a former board president of the Hitchcock Center for the Environment and teaches biology at Central Connecticut State University.
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