Monitoring, Project Development

The Avian Factor: 195 Turbines, 125 Fatalities

Oregon-based PPM Energy and Texas-based Horizon Wind Energy have released the first in a series of reports analyzing post-construction avian and bat mortality at their Maple Ridge Wind Farm, located 75 miles northeast of Syracuse, New York.

The “Annual Report for the Maple Ridge Wind Power Project, Post-construction Bird and Bat Fatality Study—2006” concluded that bird and bat fatalities found at the 231-megawatt wind farm were within the range of fatalities found during late summer and fall migration at turbines in the United States.

The wind farm itself consists of 195 wind turbines and three permanent meteorology towers on the Tug Hill Plateau of Lewis County, just west of Lowville, New York. During this first year of what will be an ongoing four-year study, carcass surveys were conducted at 50 out of 120 operational turbine sites.

Because the project itself was not operational until mid-2006, the report did not cover portions of the spring bird migration, and thus definitive estimates of bird mortality are not yet available. A total of 125 avian incidents were recorded by searchers during standardized surveys, representing 30 species.

However, the bird carcasses that were found during the study included no species listed in state or federal endangered species lists, and only one raptor—an American kestrel.

The study also found that “as with most turbine facilities across the United States, the number of fatalities of night migrants was fairly low at the Maple Ridge facility…the numbers were especially small in comparison with fatality rates of these birds at tall, guyed communication towers in the Midwestern and eastern United States, where fatalities sometimes involve hundreds or even thousands of birds in a single night or migration season.”

“The information we collect at Maple Ridge will be used to help make wind farms in New York State and across the country safer for birds and bats and help us better assess sites for new wind projects,” said Horizon Wind Energy development director Patrick Doyle.

For bats, the June to November study covered an estimate 90 percent of the period during which bats are at risk and resulted in an estimated 9.2 to 14.9 bats per megawatt per season. Although higher than predicted in pre-project studies this rate is—according to the study—lower than rates reported from Appalachian Ridges.

Remains of 326 bats were found by searchers during standardized surveys. The mix of species identified included a similar mix of species found during other wind project mortality surveys, with the largest number of incidents among hoary bats, with smaller numbers of silver-haired, little brown, red and other relatively common bat species. No bat species listed in state or federal endangered species lists were found.

In addition, the Maple Ridge Wind Farm is working closely with the New York State Energy Research and Development, Authority (NYSERDA) to facilitate NYSERDA-funded advanced radar analysis of bird and bat migration at Maple Ridge, planned for the migrations seasons of 2007 and 2008.

“On top of this extensive monitoring, the Maple Ridge Wind Farm is working with the Bat Wind Energy Cooperative and researchers from Bat Conservation International to see if we can field test experimental bat deterrent devices at Maple Ridge during the summer of 2007,” said Andy Linehan, PPM Energy’s director of wind permitting.

The 2006 study protocol was as follows:

• 50 turbines and two meteorological towers were included in the survey. (Ten turbines and one meteorological tower were checked daily, 10 turbines and one meteorological tower were checked every third day and 30 turbines are checked weekly.)
• Turbines were selected randomly, but included all representative habitat types for the project.
• Grass and other vegetation beneath the turbines were cut or cleared regularly to make it easy for searchers to find dead bats. Searcher efficiency and scavenging rate studies were also performed.
• Any carcasses found were collected and frozen for identification by experts. Bat carcasses were subject to genetic testing for species identification, radioisotope testing for determining areas of origin and mercury testing to determine bioaccumulation of pollution from fossil-burning power plants.

In addition to the post-construction studies, Maple Ridge conducted a summer bat study, a fall migration radar and night vision study, Phase I Avian Risk Assessment, and a Breeding Bird Survey before the project was approved for construction.

A multi-agency public/private team conducted the first year of a four-year study using methodology defined by the Project Technical Advisory Committee, which is comprised of the following membership: New York State Department of Environmental Conservation, U.S. Fish and Wildlife Service, New York State Energy Research and Development Authority, New York State Audubon Society, Curry and Kerlinger (responsible for implementing the design and execution of the study), Environmental Design & Research (responsible for environmental studies to support permitting for Maple Ridge Wind Farm), PPM Energy and Horizon Wind Energy. Dr. James Gibbs of State University of New York Environmental Science and Forestry was the consultant for statistical review.