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Spring 2009

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Conflict between wildlife and humans occurs when both use similar resources. These types of problems are increasing in frequency as human populations and resource use grow together.

Each year, hundreds of eastern golden eagles pass through Pennsylvania, following wind currents along the ridges that traverse north to south. At the same time, wind turbines, which sometimes kill birds, are being erected on these same ridges to generate energy.

Because the eastern golden eagle population is small and because they migrate through a narrow corridor in Pennsylvania, it is important to develop wind energy in an eagle-friendly way. With high-technology tracking devices, a project based at the National Aviary (www.aviary.org), in Pittsburgh, is following golden eagle movements in order to gather the information required to reduce wind power threats to these magnificent birds. The work is being done on the eastern population of golden eagles, in the Appalachian Mountains of western and central Pennsylvania and surrounding states, including West Virginia, Kentucky, New York, Virginia, Maryland and other states.

The project began in 2005 and involves Todd Katzner of the National Aviary; Mike Lanzone of the Powdermill Avian Research Center of the Carnegie Museum of Natural History; Trish Miller, of the Powdermill Center and Penn State University; Brady Porter and Maria Wheeler, of Duquesne University; Dave Brandes, of Lafayette College; Dan Ombalski, of the State College Bird Club; and Charles Maisonneuve, Ministère des Ressources Naturelles et de la Faune, Quebec, Canada.

People in the Appalachian region of western and central Pennsylvania and surrounding states have a unique and special responsibility for the conservation of the eastern North American population of golden eagles. This biologically distinct population is of conservation concern, and preliminary data suggest that most individuals in the population migrate through one or more narrow, 30 to 60-mile bottlenecks along the mid-Appalachian Mountains. The ridges in these bottlenecks are, according to the U.S. Fish and Wildlife Service, also the sites within the region with the highest potential for development of wind power.
Wind power development is important to U.S. and local economies and also is the world’s fastest growing energy technology. Development of wind power in the Appalachians should be conducted in a manner that will best meet the dual goals of promoting renewable energy generation and, at the same time, protecting this special population of raptors.

The goal of the eastern golden eagle research is to collect data and provide information that is believed to be essential for developers and land managers, so they can take steps to reduce the threats to eagles that are posed by turbines.

At present there is little science to guide the development of wind power on Appalachian ridges. The aim in developing this research is to produce the scientific data necessary to provide managers and elected officials at every level a rational basis for turbine siting and operation criteria to reduce risk to migrating raptors.

Photo by Todd Katzmer
golden eagle

The project’s goal is to collect information on where and how the unique eastern population of golden eagles migrates through the Appalachian Mountains and to use these data to create regional maps showing the relative risk to eagles of development of wind power in different areas. The maps are expected to provide a crucial tool for managers and elected officials to guide safer development of wind power throughout the region.

The researchers are working with existing hawk migration counts, to collect additional data on flight dynamics and eagle behavior during migration. They have also trapped and telemetered eastern golden eagles for several years  (the exact number changes as more birds are trapped and released and other tracking units become inoperative) and have that data for analysis. Katzner says that eight more eagles were captured and outfitted with telemetry equipment this past winter and at least another four will be done this coming summer.
First-stage modeling has begun by focusing on broad-scale migration patterns that will indicate the routes and rationales for eagle movement. Second-stage models that provide greater detail on the specifics of how eagles use topography and weather will follow as more data and funding are developed.
Providing information on potential impacts of wind power development on eagles in the mid-Appalachians requires a multistep strategy. The project approach focuses on three components:

  • Discover the routes along which eastern golden eagles travel when they pass through the Appalachian Mountains. To do this, researchers compile data from new and existing hawk migration counts across Appalachian ridges and track individual eagles with satellite telemetry.
  • Establish how individual birds behave as they move along these migration routes. Specifically, the project is using GPS-quality telemetry data to evaluate the altitude and flight speed of birds under a suite of climatic and topographical conditions.
  • The third and final step to this process is to incorporate these data into spatially explicit computer models to predict population-level migration patterns and individual flight behavior on migration.

With these models, region-wide maps can be developed that describe the relative risk to golden eagles of wind power development in different areas along their migration routes. These maps will allow specific recommendations to be made to mitigate the impact of development of wind power on eagles and other raptors. This project will have numerous benefits to wildlife and to people, primarily because it will provide a framework for safer development of wind power.

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