This is a complex subject, and I'm not the expert.  My son, who is an 
environmental scientist, provided the following information:

There is ONE location in North America where wind power has a significant 
negative impact on birds. In Altamont Pass, California (one of the oldest 
wind power installations in the US), a unique design has caused many birds 
to meet an untimely end. What is special about this location is that the 
turbines are spaced very close together, sit low to the ground, spin 
faster than most designs, and are mounted on a lattice framework instead 
of a single mast. The framework is an attractive place for birds to nest 
whereas they simply ignore newer high mast turbines.

Citation:

*http://www.renewableenergyworld.com/rea//news/article/2007/05/wind-
turbines-not-a-threat-to-u-s-bird-population-says-study-48393

Practically all other available research shows that turbines have no 
significant effect on birds. Much greater threats to the avian population 
come from cars, airplanes, power lines, domestic cats, and global warming. 
In fact, it has been shown that fossil-fuel power is far more harmful per 
GWh generated than wind.

Citations: 

*http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2W-4VVW4W3-
3&_user=10&_coverDate=06%2F30%
2F2009&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000
050221&_version=1&_urlVersion=0&_userid=10&md5=e5ff6861ac0b333363dc9899a784
6019

*http://www.audubon.org/bird/cat/

*http://www.usatoday.com/news/offbeat/2008-11-06-birddogs_N.htm

Aesthetics is always a debatable subject. Certainly cluttered 
installations such as the aforementioned Altamont Pass might be seen as 
unattractive. That being said, most new installations look quite different 
and surveys have shown that 70% of people either like them or are 
indifferent. Also of note is that wind farms actually attract tourists 
instead of repel them, as has often been claimed. 

Citations:

*http://www.guardian.co.uk/commentisfree/2008/aug/12/windpower.alternativee
nergy

*http://www.canada.com/edmontonjournal/news/business/story.html?
id=63a5438a-ae99-4b76-9629-b7b59d238932

______________________________________________________________________

Ohio-birds mailing list, a service of the Ohio Ornithological Society.
Our thanks to Miami University for hosting this mailing list.
Additional discussions can be found in our forums, at www.ohiobirds.org/forum/.

You can join or leave the list, or change your options, at:
http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS
Send questions or comments about the list to: [log in to unmask]