field tripWinter 2009
For the Birds
How Powdermill Nature Reserve and the National Aviary have joined forces to help the state’s golden eagles coexist with wind-power technology.  
By John Altdorfer

Avian expert Trish Miller with a threatened eastern golden eagle. Photo: Mike Lanzone

At a distance, nothing seems more peaceful or harmless than the slender blades of a wind turbine slicing through the air, ever so gracefully. These giant pinwheels seem to offer reassurance that humankind is on the right track to shrinking its enormous carbon footprint. Yet for a golden eagle migrating across the Appalachian Mountains of southwest and central Pennsylvania, a collection of whirling turbines could be an unavoidable killing field.

Trish Miller, an avian expert at Powdermill Nature Reserve, Carnegie Museum of Natural History’s biological field station near Ligonier, doesn’t want to pull the plug on the much-needed wind power industry. But she also knows that scores of dead golden eagles needn’t be the acceptable collateral damage of any “green” process.

As manager of Powdermill’s Geographical Information Systems Lab—a computerized mapping system  used to produce tools such as Mapquest and Google Earth—Miller is leading a joint research program already three years in the making that pairs Powdermill with the National Aviary to chart the migration behaviors of golden eagles in the eastern United States.

“The crux of this project is the wind power issue and protecting the golden eagle,” explains Miller. “But it also will help us discover more about the ecology and behavior of these birds as far as where they’re going, why they’re going there, and what they’re doing on the way. Those are things that we just don’t understand yet.”  

What Miller knows is that the same airstreams that aid golden eagles on their journeys also turn the turbines. That combination places the birds on a potentially deadly collision course with rock-hard reinforced Fiberglas turbine blades that can weigh 3,000 pounds or more, span a diameter longer than a football field, and rotate at speeds that top 200 miles per hour at their tips. While wind power representatives say bird fatalities are minimal, stats from a turbine site at Altamont Pass, California, show that every year about 75 golden eagles there are swatted from the skies to their deaths. A similar number of fatalities in Pennsylvania could be catastrophic for a migratory population that Miller estimates to be 1,000 to 2,000 birds.

The goal of the study, which could cost as much as $300,000 and is still seeking funding, is to produce maps that land managers, government regulators, and the wind power industry can use to guide wind power development and turbine placement—which is expected to increase 20-fold in Pennsylvania over the next 15 years. Golden eagles have been targeted for study because they’re an umbrella species that migrate along routes shared by other raptors, including bald eagles, osprey, falcons, and a variety of hawks. Many of these birds, some of which are endangered or threatened like the eastern golden eagle, follow narrow corridors through the state. Those airborne pathways, which raptors follow to take advantage of buoyant updrafts, run along the very ridge lines that wind power companies are eyeing for development.

“Projects like this let us see the effects of increasing human populations and increasing resource consumption.”
Todd Katzner, director of conservation and field research, National Aviary

To locate migration hot spots, Miller works with her Powdermill colleague and husband, Mike Lanzone, to trap and track golden eagles during their spring and fall migrations. Tipping the scales at 8 to 12 pounds, a golden eagle weighs less than the average Thanksgiving turkey. But with dagger-sharp talons that can literally tear the stuffing out of its prey, they must be handled with care.

After luring a bird to a trapping site with road-killed deer carcasses, Miller and Lanzone fire a 40- by 60-foot net from a pneumatic air cannon to pin it to the ground. Bare-handed, they place a hood over the bird’s head and booties on its ever-dangerous talons. Then they carefully strap a solar-powered, cell phone-size, 3.5-ounce tracking unit between the bird’s shoulder blades, a task that can take up to two hours to complete. In flight, the $3,000 device records every 30 to 60 seconds the golden eagle’s altitude, direction, speed, and location. Outside of Pennsylvania and on the ground, it collects information every 15 minutes, relaying data back to Powdermill via the network of cellular phone towers.

According to the National Aviary’s director of conservation and field research Todd Katzner, the project, set for completion next year, can provide benefits for humans, birds, and the world we share.

“Projects like this let us see the effects of increasing human populations and increasing resource consumption,” he says. “Of course, we want to maintain the quality of life we enjoy now, but we also want to protect the environment so that golden eagles are here for future generations of people to enjoy.”

Collaborating with Powdermill was a natural selection, explains Katzner, who immediately set out to find a research partner upon his arrival at the Aviary five years ago.

“Powdermill is the obvious place to turn in western Pennsylvania if you’re interested in finding a research partner in the ornithological world,” he says. “It has a great reputation and solid core of people. And Trish is poised to become the foremost person with knowledge    of golden eagles in the eastern United States because of the time and energy she’s put into this project and the quality of the work it’s producing.”

Though definitive results and recommendations are several years away, Miller is hopeful that it will all be put to practical use.

“We want to create models that will help us show that, in some cases, turbines could be built a hundred meters from a projected site so that they could still harness the power of the wind but without presenting an increased risk to the golden eagles,” she explains. “With careful planning, we can make sure there's enough room in the skies for wind turbines and golden eagles.”
Also in this issue:

The Art of Daily Life  ·  Putting the Popular in Science  ·  Welcome  ·  Clearing a New Path  ·  Directors' Note  ·  NewsWorthy  ·  Face Time: Lynn Zelevansky  ·  Artistic License: Break-Out Performance  ·  About Town: Social Science  ·  Science & Nature: The Lord of the Flies  ·  Big Picture