Avian, bat and habitat cumulative impacts associated with wind energy development in the Columbia Plateau Ecoregion Of eastern Washington and Oregon

Abstract

Wind energy development is occurring in Oregon and Washington within the Columbia Plateau physiographic region (ecoregion). With this development comes the potential for direct impacts to birds and bats through collision mortality and for indirect effects through habitat fragmentation or displacement of birds and other wildlife. Collision mortality is well documented at most wind energy facilities, but population level effects have not been detected, although few studies have addressed this issue. The purpose of this report is to estimate cumulative impacts associated with wind energy development projected to occur within the Columbia Plateau Ecoregion (CPE) of eastern Washington and Oregon through 2015. This report updates two previous versions to account for additional bird and bat fatality estimates from several wind energy facilities where monitoring reports recently became available. For the purpose of this analysis, we assumed that for cumulative impacts to occur, there must be a potential for a long-term reduction in the size of a population of birds or bats. When assessing the potential for cumulative impacts, it is necessary to first define the population potentially affected by wind energy development. Because birds and other animals do not recognize geopolitical boundaries, we have defined the affected population as those birds and bats of each species that breed, winter, or migrate through the CPE. As of December 14, 2010, there were 4,059 megawatts (MW) of installed wind energy in Washington and Oregon, most of which is within the CPE. For this analysis, we assumed that 6,700 MW of wind power would be present in the CPE.