Jul 15 2013

Appropriately Responding to Bird Fatalities caused by Wind Turbines

One of the most widely publicized disadvantages of wind turbines, on or offshore, is the threat that the spinning blades pose to migratory birds. It’s no secret that thousands of birds, including endangered species and everything from large raptors to small songbirds, are killed each year due to collisions with wind turbine blades (Erickson, 2005). Considering this affect of wind turbines in assessments of wind energy sources is necessary and crucial. However, instead of discussing possible solutions, public reaction to this issue has been to dismiss wind energy as a whole. Bird mortality due to wind turbines is not only over-reported, but it is blown out of proportion and sensationalized by using biased figures and reporting the same isolated events. By focusing on the whole picture, putting this issue into proportion, and discussing the steps that have already been taken to minimize bird mortality rates in the wind energy sector, we can appropriately respond to this concern and move forward.

altamont pass

View of Altamont Pass Wind Farm
From Flikr Creative Commons; “Valley of Wind” by user Jay Galvin; May 30, 2005

The public first caught wind of this issue when reports exposed that the turbines at the Altamont Pass Wind Resource Area in California collectively kill about 4,700 birds each year (Bogo, 2007). The Altamont Pass Wind Resource Area opened in 1982 and is the deadliest wind farm to date in terms of bird mortality. These numbers are devastating. Avian conservationists and the general public questioned the wind energy sector with good reason. Better environmental assessment should have been completed in advance to avoid such a high death toll. A report from The Center for Biological Diversity summarizes the problems with the location of Altamont Pass:

“The bird kill fiasco at Altamont Pass is a result of poor planning that allowed wind turbines to be built along a major raptor migration corridor in an area with high wintering concentrations of raptors and in the heart of the highest concentration of golden eagles in North America.” (Center for Biological Diversity, http://www.biologicaldiversity.org/campaigns/protecting_birds_of_prey_at_altamont_pass/pdfs/factsheet.pdf)

Simple precautions  can be taken that are now obvious (because of the mistakes at Altamont Pass) such as avoiding designated areas with migratory bird traffic and areas that are known habitat for endangered birds. But the fiasco at Altamont Pass also created an opportunity for some of the research and assessment that should have occurred before constructing a 5,200 turbine wind farm. A very comprehensive study ran from 2000 to 2005 in order to assess the best management practices for wind farms in order to minimize bird fatalities (Smallwood, 2009). Another group directly studied Altamont Pass in order to reduce avian deaths going forward. Evidence from this study concluded that a 50% reduction in bird deaths at the Altamont facility would be possible with modern, larger turbines that are designed to reduce bird collisions. Here is a graph of the most recent data on bird fatalities from the Altamont Pass Wind Resource Area:

altamont pass data

Draft of Altamont Pass Wind Resource Area Bird Fatality Study, Bird Years
2005–2011; Leslie et. al.; March 2013

It is important to recognize the Altamont Pass Wind Resource Area as a wake-up call. The situation was sensationalized with good reason, but even the avian and wildlife conservation societies have recognized the move forward. The National Audubon Society has worked with The Nature Conservancy, US Fish and Wildlife Service, Defenders of Wildlife, and Massachusetts Audubon and Bat Conservation International under the Federal Advisory Committee Act (FACA) to create wind turbine guidelines (The National Audubon Society, 2012).  (Guidelines can be found at the following link: http://www.fws.gov/windenergy/) The only groups still sitting around gossiping about the horrors of the Altamont Pass Wind Resource Area are opponents of wind energy. Understandably, wind energy opponents would like to live in the past and sensationalize bird fatalities as opposed to recognizing the efforts to move forward. However, I hope that more current and realistic reports reach the public so that they can make up their own mind about wind energy.

Setting Altamont aside, it is interesting when you put the issue of turbine-caused bird fatalities in perspective. It is estimated that 28,500 bird fatalities occur each year due to wind turbine collisions (Erickson, 2005) around the world. How does that stack up to other causes of bird mortality, such as power lines? or (more appropriately) oil spills?

Out of a yearly estimated 853,551,500 bird deaths, here is a pie chart showing the each source of bird mortality and the percentage of mortality from that source (as estimated in the study A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions, by Erickson et al.):

bird mortality

Erickson et. al; A Summary and Comparison of Bird Mortality from
Anthropogenic Causes with an Emphasis on Collisions

As seen in the graph, wind turbines barely make it on to the pie chart. Wind turbine collisions are dumped into the “Other” category (at about 0.01%) along with airplanes and environmental disruptions. The report estimated that turbine collisions constitute less than 0.01% of the annual bird fatalities in the world. The full data table is below:

Erickson et.al.; A Summary and Comparison of Bird Mortality from  Anthropogenic Causes with an Emphasis on Collisions; 2005

Erickson et.al.; A Summary and Comparison of Bird Mortality from
Anthropogenic Causes with an Emphasis on Collisions; 2005

Unfortunately, we cannot accurately compare estimated avian death tolls for fossil fuel production methods with wind turbine collisions because data is not available for an accurate comparison. It does seems plausible that oil spills and mountain top removal probably kill their fair share of birds (and destroy bird habitats) each year.

It is important for the leaders of the wind energy movement to make efforts to publicize their efforts moving forward and to continue research to further reduce the chance of collision deaths. As offshore wind turbine technology and implementation is improved, further research should assess environmental  and ecological impacts thoroughly to avoid another renewable energy setback.  It’s time to leave the opponents in the dust and prove that wind energy, and renewable energy as a whole, can move forward with a not-so-clean record, but a clean intentions and a clean future ahead.


Bogo, J., 2007, How the Deadliest Wind Farm Can Save the Birds: Green Machine, Popular Mechanics, http://www.popularmechanics.com/science/environment/green-energy/4222351, (July 14, 2013)

Center for Biological Diversity, Fact Sheet on Altamont Pass Bird Kills, http://www.biologicaldiversity.org/campaigns/protecting_birds_of_prey_at_altamont_pass/pdfs/factsheet.pdf, (July 14, 2013)

Erickson, W. P., Johnson, G. D., Young, D.P. Jr., 2005,  A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions, USDA Forest Service Gen. Tech. Rep. PSW-GTR-191., http://www.dialight.com/Assets%5CApplication_Notes%5CSignaling%5CObstruction%20Lighting%20Bird%20Strike%20Study.pdf, (July 14, 2013)

Leslie, D., Schwartz J., and Karas, B.,  Draft of Altamont Pass Wind Resource Area Bird Fatality Study, Bird Years 2005-2011, Rep. no. M96, ICF International,  http://www.altamontsrc.org/alt_doc/m96_apwra_2005_2011_draft_bird_fatality_report.pdf, (July 14, 2013)

The National Audubon Society, 2013, Federal Guidelines a Step Forward for Bird-Friendly Wind Development, http://www.audubon.org/newsroom/press-releases/2012/federal-guidelines-step-forward-bird-friendly-wind-development, (July 14, 2013)

Smallwood, K. S., Rugge, L., and Morrison, M. L., 2009, Influence of Behavior on Bird Mortality in Wind Energy Developments, The Journal of Wildlife Management , Vol. 73, No. 7, (July 14, 2013)

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