assessing the degree to which a particular site is acceptable for wind-energy development and the types of research and monitoring needed to help inform decision makers.

INTRODUCTION

There are two major ways that wind-energy development may influence ecosystem structure and functioning—through direct impacts on individual organisms and through impacts on habitat structure and functioning. Environmental influences of wind-energy facilities can propagate across a wide range of spatial scales, from the location of a single turbine to landscapes, regions, and the planet, and a range of temporal scales from short-term noise to long-term influences on habitat structure and influences on presence of species. In this chapter, we review the documented and potential influences of wind-energy development on ecosystem structure and functioning, focusing on scales of relevance to siting decisions and on influences on birds, bats, and other vertebrates.

Construction and operation of wind-energy facilities directly influence ecosystem structure. Site preparation activities, large machinery, transportation of turbine elements, and “feeder lines,” transmission lines that lead from the wind-energy facility to the electricity grid, all can lead to removal of vegetation, disturbance, and compaction of soil, soil erosion, and changes in hydrologic features. Although many of these activities are relatively local and short-term in practice (e.g., construction), there may be substantial effects on habitat quality for a variety of organisms. These changes will likely be detrimental to some species and beneficial to others. Wind-energy development that is focused on specific topographic features (e.g., ridgelines) that represent key habitat features for some species may have disproportionately detrimental impacts on those species that depend on or are closely associated with these habitats.

Recent reviews of available literature have clearly documented direct impacts of wind turbines on birds and bats (GAO 2005; Barclay and Kurta 2007; Kunz et al. 2007), including death from colliding with turbine blades. As discussed below, little is known about the circumstances contributing to fatalities, but issues such as turbine height and design, rotor velocity, number and dispersion of turbines, location of the turbine on the landscape, and the abundance, migration, and behavioral characteristics of each species present are likely to influence fatality rates. In addition, non-flying organisms may be affected by turbine construction and operation, because of alteration of habitat and behavioral avoidance, possibly due to noise, vibration, motion of turbines, or their mere presence in the landscape.

We can make three general predictions about the large-scale and longterm impacts of individual fatalities. First, life-history theory predicts that



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