BBC Research & Consulting's 2005 report for the National Wind Coordinating Committee that studies 9 wind plant sitings in an effort to identify circumstances that distinguish welcomed projects from projects that were not accepted by communities.

...additional radar studies would be required to see if spring migration patterns are different than those measured in the fall. Typically spring migration is shorter than fall migration with fewer numbers in the shorter period of time. How this will affect the numbers of birds passing through the rotor swept volume is unknown. It is important to determine the seasonal timing, altitude and numbers of migrant birds passing over the proposed project site and the effects of weather upon their passage over a greater part of the whole year. In addition, it is possible to determine some of the bird and bat species passing through the project site by accoustical sensors to determine which species, that make vocal calls, are migrating through the site.

This letter from the West Virginia Field Office of the US Fish and Wildlife Service to NedPower Mount Storm responds to the developer's biological assessment for endangered bats at the proposed Mount Storm Windpower project site to be located in Grant County, West Virginia.

This graphic shows the relationship between the height of turbines and the collision threat to nocturnal migrants at the Chautauqua Wind Farm, NY, in the Fall of 2003. A companion graphic included in the NWW photo gallery depicts this threat to noctural migrants in the Spring of 2003.

This graphic shows the relationship between the height of turbines and the collision threat to nocturnal migrants at the Chautauqua Wind Farm, NY, in the Spring of 2003. A companion graphic included in the NWW photo gallery depicts this threat to noctural migrants in the Fall of 2003.