Much monitoring and research has been conducted on the interactions of birds and wind turbines, primarily due to the potential for direct impacts due to collision with wind turbine blades. The USFWS Wind Energy Guidelines implemented in 2009 has led to hundreds of studies of avian mortality, potential displacement effects and other studies of the interactions of birds with wind turbines. We review and standardize the data for disparate methods for a meta-analysis of these studies.
Based on the fatality studies, it is estimated that an average of around 3 to 5 birds/MW are impacted by wind turbines. Broken down by taxa, the estimates are approximately 2 to 4 passerines per MW, 0.1 to 0.2 raptors/MW, and 0.1 to 0.2 water-associated birds/MW with other groups comprising the remaining amount. While passerine numbers are the highest, impacts are spread across many species and the level of impact is highly unlikely to affect any individual species populations. We summarize the results of these meta-analyses of avian mortality. We also provide a review of the strategies that have been implemented to potentially reduce and minimize passerine impacts. These include minimized and proper lighting of the wind turbines and associated infrastructure, use of unguyed met equipment, and macro and micro siting of projects and turbines.