People who oppose wind farms often claim wind turbine blades kill large numbers of birds, often referring to them as “bird choppers”. And claims of dangers to iconic or rare birds, especially raptors, have attracted a lot of attention.
Wind turbine blades do indeed kill birds and bats, but their contribution to total bird deaths is extremely low, as these three studies show.
A 2009 study using US and European data on bird deaths estimated the number of birds killed per unit of power generated by wind, fossil fuel and nuclear power systems.
It concluded, “Wind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour (GWh) of electricity while fossil-fuelled power stations are responsible for about 5.2 fatalities per GWh.”
That’s nearly 15 times more. From this, the author estimated that wind farms killed approximately seven thousand birds in the United States in 2006 but nuclear plants killed about 327,000 and fossil-fuelled power plants 14.5 million.
In other words, for every one bird killed by a wind turbine, nuclear and fossil fuel powered plants killed 2,118 birds.
A Spanish study involved daily inspections of the ground around 20 wind farms with 252 turbines from 2005 to 2008. It found 596 dead birds.
The turbines in the sample had been working for different times during the study period (between 11 and 34 months), with the average annual number of fatalities per turbine being just 1.33. The authors noted this was one of the highest collision rates reported in the world research literature.
Raptor collisions accounted for 36% of total bird deaths (214 deaths), most of which were griffon vultures (138 birds, 23% of total mortality). The study area was in the southernmost area of Spain near Gibraltar, which is a migratory zone for birds from Morocco into Spain.
Perhaps the most comprehensive report was published in the journal Avian Conservation and Ecology in 2013 by scientists from Canada’s Environment Canada, Wildlife Research Division.