The Blue Sky Green Field Wind Farm began commercial operation in May of 2008. The wind farm is located near the towns of Calumet and Marshfield in Fond du Lac County, Wisconsin. The wind farm consists of 88 Vestas V-82 wind turbines that rise to approximately 397 feet (121 meters) at the highest point at the top of a turbine blade. Each wind turbine is capable of generating 1.65 MW of electricity, and the wind farm as a whole is capable of generating 145 MW of electricity, or enough to provide power to 36,000 average residences. Here, we report interim results of fatality studies at Blue Sky Green Field based on the first season of data collection. Caution should be taken when reviewing the results; these data are from one fall season and should not be extrapolated to determine a potential annual estimate.
From July 21 to October 31, 2008 we conducted the first season of a year of studies designed to estimate the number of bird and bat fatalities attributable to wind turbine operation. These dates correspond with the late-summer and fall migration periods for birds and bats, though the beginning of this period may begin as early as July 15. These studies included systematic searches at a random sample of 30 turbines at daily and weekly intervals. We also conducted trials designed to estimate potential sources of bias, including searcher efficiency and scavenger removal rates. While previous research has indicated that nearly all of the fatalities to birds and bats from wind turbine collisions occur during the late summer and fall, we will conduct a second season of fatality monitoring from March 15 to May 31, 2009, which will correspond to the spring migrating season. Based on the results from that portion of the study, we will combine both seasons and produce annual estimates of fatalities. The final report will also incorporate ancillary data such as meteorological conditions and estimates of bat activity that were recorded concurrent to the fatality searches to determine if there are correlations between these variables and the timing or number of fatalities. We do not address these analyses in this interim report.
This study represents only the fifth such study we are aware to estimate bird and bat fatalities from wind turbine operation in the Midwest, and contributes to our understanding of wind energy impacts to birds and bats. As more wind power projects are built in the region, and additional studies become available, a clearer picture of the impacts to birds and bats will emerge.