How do bird mortality rates at wind farm projects compare to other sources of collision-related avian mortality?
The Cato Institute projects: “Ten thousand cumulative (emphasis added) bird deaths from 1,731 MW of installed U.S. capacity [as of 1995] are the equivalent of 4.4 million bird deaths across the entire capacity of the U.S. electricity market (approximately 770 GW)” (Bradley 1997), and uses this figure as argument against expansion of wind energy. Furthermore, the American Bird Conservancy estimates that feral and domestic outdoor cats probably kill on the order of hundreds of millions of birds per year (Case 2000). One study estimated that in Wisconsin alone, annual bird kill by rural cats might range from 7.8 to 217 million birds per year (Colemen & Temple 1995). The numbers of bird kills vary from project to project as well as the potential impact to bird populations. The critical questions that remain to be addressed include local impacts to bird populations especially raptors and avoiding high concentration areas, especially during migration. Better mortality studies are also needed
