Another significant cause of songbird mortality is towers. Towers are particularly deadly to nocturnally migrating species.
The U.S. Fish and Wildlife Service states that four to five million birds are killed each year by towers, many of those killed are members of species which are in danger.
Loss of migratory birds at communication towers is estimated at 4-5 million annually. Potentially impacted resources include 90 bird species which are threatened or endangered and 124 non-game species of management concern.
http://www.fws.gov/habitatconservation/communicationtowers.htm or click here
The American Bird Conservancy has an interesting and informative pdf file on their site, Communication Towers: A Deadly Hazard To Birds A Report Compiled by American Bird Conservancy Documenting The Killing of 230 Bird Species, dated June 2000.
The report is based on data collected from 46 locations in the mid to eastern United States and one in Canada. It includes lots of purty graphs which present a visual comparison of the species documented. http://www.abcbirds.org/policy/towerkillweb.pdf *Do not click on this link if you have a slow connection.