Bird Mortality at a Wind-Energy Facility near a Wetland of International Importance

Abstract

Wind turbines provide a source of renewable energy to meet increasing human demand and offset the costs of fossil fuel usage and nuclear power generation. Birds are killed and displaced at wind facilities, so increased understanding of the drivers of mortality and displacement will assist planners considering the future placement and use of wind facilities. Our objectives were to assess the effect on birds of a wind facility in southeastern Wisconsin by (1) recording the species composition of recovered bird carcasses, (2) estimating mortality rates, and (3) identifying variables correlated with fatalities. We found 20 bird carcasses during scheduled searches. On this basis, we estimated that over two springs and two autumns of study from 2008 to 2010, 607 birds (0.026 per turbine per day, 0.017 per megawatt per day) were killed over 277 days of searching at this facility containing 86 turbines. Nocturnally migrating passerines accounted for 50% of the birds found killed. We found a significant negative relationship between bird fatalities and northward movement of birds through the wind facility. Despite the close proximity of Horicon Marsh National Wildlife Refuge, a wetland of international importance, we found no relationship between distance to Horicon Marsh and bird fatalities. Our study provides a timely assessment of fatal bird collisions with turbines at a wind facility in agricultural lands, uniquely located near a large wetland at which migrating birds stage.