Abstract
In 1994, Northern States Power Company (NSP) initiated a windpower development project that may eventually produce 425 megawatts (MW) of electricity. The first phase (P1) was developed by Kenetech Windpower, Inc. (Kenetech) in 1994 and consists of a 25-megawatt (MW) wind plant comprised of 73 turbines on Buffalo Ridge, Minnesota. The second phase (P2) consists of a 107.25 MW wind plant comprised of 143 turbines. This facility was completed by Enron Corporation in 1998, and is the world's largest single wind farm project. The third phase (P3) consists of a 103.5 MW wind plant comprised of 138 turbines. This facility was completed by Enron in 1999.
The primary goals of this study were to evaluate risk to birds from each phase of development and the cumulative risk to birds from all windpower development in the WRA. The secondary goal was to provide information that can be used to reduce the risk to birds from subsequent developments. This monitoring study used the before/after and control/impact (BACI) design. The design and analysis used a "weight of evidence" approach to assess effects of the project on species of concern. One hundred meter radius point count surveys were conducted to estimate species composition, relative abundance, habitat use, flight behavior and relative risk during the period 15 March to 15 November, 1996-1999 at turbine locations and at randomly selected stations within the WRA. Raptor and other large bird (RLB) 0.8-km radius point count surveys were conducted at randomly located points throughout the WRA to estimate the same parameters for these birds. Carcass searches were conducted at turbine locations and at randomly selected plots throughout the WRA to estimate number of avian and bat mortalities attributable to wind turbine collisions for the entire Buffalo Ridge WRA, and to relate the mortalities by species to the relative abundance of each species, turbine characteristics, habitat and other parameters to aid in determining relative risk to that species. An estimate of the total number of avian and bat fatalities in each phase of the wind development area was made.