...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.