Currently, wind energy plants have been constructed or plans are being developed for projects in at least 13 states within the United States, also Canada, Sweden, Denmark, Germany, Netherlands, United Kingdom, Spain and Scotland (EPRI 1994, Winkelman 1994). Approximately, 16,000 wind turbines currently operate in California, making this area the largest concentration of wind energy development in the world. Notwithstanding its positive social values, wind energy has been shown to cause avian mortalities. Since the 1970`s many studies have been done to understand the interaction between wind energy development and birds. However our knowledge and understanding of bird interactions with wind energy development is incomplete.