Effects of Wind Turbines On Nongame Birds in Conservation Reserve Program Grasslands in Southwestern Minnesota

Abstract

One concern of wind power development for electrical energy generation has been the potential for bird collisions with wind turbines. The effects of wind turbines on nongame bird composition and density in Conservation Reserve Program (CRP) grasslands was evaluated in summer 1995 along Buffalo Ridge in southwestern Minnesota. Bird density in CRP fields with wind turbines was compared with that found in cropland, pastureland, woodland, and CRP grasslands without the presence of wind turbines. Bird species composition and density were determined within fixed width (40 m) transects. Nongame bird species richness and density were greater in woodlands and CRP grasslands than in pastureland and cropland. Bird species composition was not greatly affected by the presence of individual wind turbines. However, bird density was approximately four times less along the wind turbine string than at 180 m from the turbine string. At 180 m, bird density and species composition was similar to that found in CRP grassland control sites. Visual obstruction readings and effective vegetative height were highest in CRP grasslands followed by pastureland and cropland. Results of this study indicate that habitat type is important for future management decisions concerning the placement of wind turbines. If density of nesting (breeding) birds is a major concern relative to bird mortality, these results indicate that keeping adjacent land cropped or pastured would reduce passerine bird densities near turbines.