While still a small component of overall energy output in the US (0.3%), wind energy is the fastest growing energy source in the country.

With 16,000 utility grade wind turbines in operation in 30 states, and the industry poised for growth, concerns over how wind energy production may affect birds and wildlife focus in three areas:

• The most widely noted are fatalities resulting from collisions with rotors, towers, power lines, or with other related structures. Electrocution on power lines is also possible.
• Birds may avoid wind turbines and the habitat surrounding them.
• Direct impacts on bird habitat from the footprint of turbines, roads, power lines, and auxiliary buildings.

Annual per-turbine mortality rates average 2.19 birds or 1.825 outside of California (with the highest recorded per turbine mortality of 7.5 at Buffalo Mountain, Tennessee). To put that number in perspective, many man-made structures—from our existing power lines causing electrocutions to collisions with the windows of our homes—cause tens of millions of bird deaths per year. Bird deaths from domestic cats alone are estimated to range in the hundreds of millions per year.

Still, more man made items in the environment create a number of environmental concerns, according to Gerald Winegrad of the American Bird Conservancy.

One of the key concerns is mortality or other effects on ESA-listed species or Birds of Conservation Concern. A wide variety of bird species have been killed at wind turbine sites—of particular concern are species of owls, hawks, and other raptors, sparrows, wrens, and warblers.

Measures can be taken to prevent/minimize avian and other wildlife impacts at each wind energy project, Winegrad writes, including:

• A thorough review for potential avian mortality and disturbance of critical habitat should be conducted before construction of any new wind energy project.
• Bird impacts due to habitat fragmentation and any other habitat impacts related to construction and/or operation of a wind facility should be thoroughly evaluated and measures should be taken to prevent/minimize mortality and non-lethal impacts.
• Projects should be sited on areas with disturbed habitat wherever possible.
• Sites with major bird attractants (such as Altamont Pass, California) should be avoided.
• Attention should be paid to impacts on specific species, not just general numbers of kills.
• The use of guy wires should be avoided.
• Transmission lines should be placed underground to minimize project footprint.
• Lighting should be minimized, with only a limited number of towers being lit using only white or red strobes at no more than 24 pulses per minute.
• Sites should be monitored using scientifically rigorous methods, and data should be published.

On a related note, The National Audobon Society announced its support for wind turbine development last year.