A River of Raptors

An ornithologist’s season counting hawks atop Chestnut Ridge.

Cameron Rutt spends countless hours counting birds like this broad-winged hawk [Credit: David Maher, flickr.com].
By | Posted March 1, 2009
Posted in: Environment
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Today, under a low and leaden sky, the north wind offers nothing. Cameron Rutt has been standing atop the ridge since daybreak, logging his 514th hour of observation since late August – a season that has, by every measure, eclipsed all those in recent memory. But not today. “This is by far the slowest day of the season.” He sounds apologetic, as though he is not merely an observer, but a conductor whose symphony is performing poorly.

As official counter at the Chestnut Ridge hawk watch in Bedford, NY, a bucolic bedroom community an hour north of Manhattan, Rutt has, for nearly three months now, ascended the ridge at dawn, six days a week, to record the passage of migrating raptors – birds of prey ranging from diminutive kestrels to golden eagles. The numbers are not inconsequential. Biologists rely on this data to discern the subtle ebb and flow of bird populations.

Rutt’s present occupation is not for the faint of heart. “The worst part would have to be the long hours spent in solitary confinement, when nobody visits for much of the day,” he says. “A season’s worth of these days adds up very quickly.”

Nor is counting hawks a stable or well-compensated vocation. Since earning an undergraduate degree earlier this year, Rutt has held a series of typically low-paying seasonal research jobs, deliberately and painstakingly acquiring the skills of the field ornithologist. He has conducted auditory surveys, captured and banded birds in mist-netting operations and generally lived the life of an itinerant birder.

But there are other compensations. He has chased rare birds throughout the United States and Canada, Europe, the Caribbean, Costa Rica and Panama. Rutt, like so many addicted to this avian pursuit, is an unabashed lister, having documented nearly 600 of the 891 birds endemic to North America. Nearing the 600 mark places him in rarified air among birders. But Rutt has been at this game for nearly 11 years now. This passion for birds, he says, took flight when he was just nine years old.

Unlike the more remote places Rutt has traveled, Chestnut Ridge is not nature at its most pristine. The constant hum of Interstate 684 rises up the ridge like a hawk ascending a thermal air current. And oddly, there are no chestnut trees. Decimated by blight, chestnuts here have long since given way to dense stands of aspens, oaks and maples. “In many ways,” Rutt says, “Chestnut Ridge is not an ideal location for raptor migration.”

Since 1983, though, the ridge has averaged more than 13,000 hawks per season, nearly 25 for each hour of observation. Depending on the vagaries of wind and weather and the success or failure of breeding populations in Quebec, the Canadian Maritimes and New England, Rutt will, by season’s end, have counted nearly 20,000 hawks from his vantage on the ridge – far more birds in three short months than most people will notice in a lifetime.

But these statistics belie the erratic patterns of migration. The wind seldom delivers a steady stream of birds. It is either deluge or drought. Then too, the topography of the ridge favors certain species over others. Well to the west, golden eagles and goshawks abound; to the east, peregrine falcons. Like bush pilots following mountain ridges, river valleys and meandering coastlines, migrating hawks follow preferred leading lines – features of land and wind – that direct their flight and provide free uplift.

At Chestnut Ridge, it is almost all broad-winged hawks. Accounting for nearly 60 percent of all birds observed here, these diminutive raptors with short, rounded wings surf the strong northwest winds and conserve energy by catching powerful updrafts bending off the cliffs. Nearly all broad-wings pass during several days in early autumn. Rutt has recorded 9,379 broad-wings this season, more than half observed over several hours on a mid-September afternoon. At that pace, it is all he can do to keep up.

The data Rutt collects at Chestnut Ridge are fed to the Hawk Migration Association of North America, a nonprofit group that catalogs raptor migration records from more than 200 hawk watch sites throughout the United States, Canada and Mexico. These records, some stretching in an unbroken line back to the early 1960s, are sliced and diced in myriad ways by scientists looking to extract some essential truths about raptor migration.

Researchers like Chris Farmer, a biologist at Pennsylvania’s Hawk Mountain Sanctuary, rely on the data collected by counters to map broad population trends among raptor species. “It’s definitely the case,” he says, “where amateur volunteer data collection that is done consistently has tremendous value for conservation.”

This tag-team of observation and analysis signaled the precipitous decline of peregrine falcons in the early 1970s in the wake of widespread use of the pesticide DDT and enabled swift action that reversed the trend within two decades. In recent years, Farmer and his colleagues have used hawk watch data to quantify worrying decreases among American kestrels and northern harriers.

But not all trends point downwards. “We have more species that are reporting large-scale increases,” says Ernesto Ruelas Inzunza, a raptor biologist at the Cornell Laboratory of Ornithology in Ithaca, NY, “such as bald eagles, merlins, peregrine falcons and osprey, who are doing pretty well for the most part.”

As November draws to a close, the northwest winds marching past the ridge will grow increasingly cold and hawks increasingly scarce. With his season on the ridge nearly complete, Rutt has documented more birds here than any autumn in recent memory. Still, he considers himself something of a novice among hawk counters, some of whom have been at this for nearly a lifetime. “Once, a kettle of approximately 600 birds appeared right overhead, with me and another observer relegated to simply estimating the whole mass,” he says. “Perhaps if I were to do it all over again, I might develop some more intelligent strategies.”

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Posted in: Environment

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