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152 <br />migratory bird exposures. Finally, the towers pose a physical obstacle in which birds can <br />become entangled or into which they may collide. <br />Vulnerable migratory species breed during the spring and summer in North America and <br />migrate to the southern states, the Caribbean, or Central and South America during the <br />fall and winter. They generally fly at night and are most susceptible to tower collisions <br />during misty, foggy, rainy, or low-cloud atmospheric conditions. During these inclement <br />weather conditions, migratory birds seem to switch from their innate, nighttime <br />navigational abilities to visual reckoning. They can become attracted, more accurately, <br />they are reluctant to leave the lit area of red, pulsing navigational strobe lights, continue <br />to fly around the lit tower, and often collide with or become entangled with the tower and <br />tower guy wires. <br />Migration occurs over a broad front in May and September-October across the Triangle <br />region. Orange County does not seem to have a significant migratory flight pattern. Most <br />species migrate fairly evenly across the county and can stop over wherever there are <br />woods, according to local experts. <br />Options. The United Scares Fish and Wildlife Service strongly encourages <br />telecommunication towers to: <br />1. Collocate on existing structures; <br />2. Keep telecommunication tower height under 200 feet, so that it can be unguyed, and <br />unlit; <br />3. Consider the cumulative and individual impacts of each tower; <br />4. If collocation is not possible, consider locations in existing "antenna farms;" <br />5. For towers over 200 feet high, install white, up-shielded, night lighting with a <br />minimum number of lights, minimum intensity, and minimum flashing rates, under <br />FCC telecommunication tower regulations; <br />6. For guyed towers, use daytime, visual bird diverter devices; <br />7. Locate towers away from wildlife habitat, wetlands, or natural resource corridors, <br />and minimize natural habitat disruption; <br />8. Locate proposed sites away from known avian habitat areas, <br />9. Accommodate at least two additional antenna arrays on each new tower; <br />10. Require all lighting and equipment to be shielded and buffered with natural <br />vegetation; <br />11. Coordinate with local researchers to conduct migratory bird mortality studies to gain <br />better information on the impacts of different tower height, configuration and <br />lighting systems; and <br />12. Provide legal mechanisms to remove towers no longer in use or when determined to <br />be obsolete. <br />It does not appear that any area of Orange County is more susceptible to foggy and ]ow <br />visibility conditions than others, except for wetlands and riverine corridors. <br />12 <br />