Big Wind & Avian Mortality (Part I: Problem Identification)
“The [2004 California Energy Commission] study also discussed how higher raptor mortality occurred when smaller towers were “upgraded” with larger turbines and proportionally longer blades. These wind turbines offered what raptors perceived as intermediate to very big windows of opportunity to fly through what looked like open spaces between towers…. However, the industry … rapidly installed thousands of these much larger turbines across America … and focused attention on new study results that reflected far less accurate (and honest) searches and surveys.”
In 1984, the California Energy Commission concluded in regard to the state’s wind industry: “[M]any institutional, engineering, environmental and economic issues must be resolved before the industry is secure and its growth can be assured.” Though it was between the lines, the primary environmental issue alluded to was the extreme hazard that wind turbines posed to raptors.
But the wind industry pretty much knew that there was little that could be done to make its propeller-style turbines safe for raptors. With exposed blade tips spinning in open space at speeds up to 200 mph, it was impossible. Wind developers also knew they would have a public relations nightmare if people ever learned how many eagles are actually being cut in half – or left with a smashed wing, to stumble around for days before dying.
To hide this inconvenient truth, strict wind farm operating guidelines were established – including high security around turbines, gag orders in agreements, and the prevention of accurate, meaningful mortality studies.
Some three decades later, the wind developers’ hide-the-problem strategy has largely hidden the avian mortality problem. While the public has some understanding that birds are killed by wind turbines, it doesn’t have a clue about the real mortality numbers.
And the industry gets rewarded with a raft of special ratepayer and taxpayer subsidies–and immunity from endangered species and other wildlife laws.
Early Studies: Problem Identification
To fully grasp the wind turbine mortality problem, one needs to examine a 2004 report about the Altamont Pass Wind Resource Area (APWRA) by the California Energy Commission (CEC). Developing Methods to Reduce Bird Mortality in the Altamont Pass Wind Resource Area. The study usefully began (p. 1):
For decades, research has shown that wind turbines in the Altamont Pass Wind Resource Area (APWRA) kill many birds, including raptors, which as protected by the Migratory Bird Treaty Act, the Bald and Golden Eagle Protection Act, and/or state and federal Endangered Species Acts. Each violation of these acts can result in fines and/or criminal convictions.
The study’s five-year review (1998–2003) was partial (the researchers did not have full access to all the Altamont turbines) but illustrative of a great problem.
This careful, honest effort analyzed turbine characteristics in relation to mortality and estimated mortality from body counts compiled in careful searches. Researchers then adjusted mortality numbers by examining statistical data based on searcher efficiency and other factors, such as carcass removal by predators and scavengers. The report even suggested that the mortality estimates probably erred on the low side, due to missed carcasses and other human errors.
This study stands in marked contrast to studies being conducted today, especially the Wildlife Reporting Response System, which is currently the only analysis happening or permitted at most wind farms. The WRRS is the power companies’ own fatality reporting system, and allows paid personnel to collect and count carcasses. It explains why mortality numbers are always on the low side and why many high-profile species are disappearing near turbine installations.
Incredibly, the APWRA report actually admitted (chapter 3, p. 52):
We found one raptor carcass buried under rocks and another stuffed in a ground squirrel burrow. One operator neglected to inform us when a golden eagle was removed as part of the WRRS. Based on these experiences, it is possible that we missed other carcasses that were removed.
It’s easy to see how human “errors” keep bird mortality low.
The APWRA study also documented that raptor food sources, turbine sizes and turbine placement all directly affect raptor mortality. It was thus able to identify many of the most dangerous turbines or groups of turbines – those with a history of killing golden eagles, kestrels, burrowing owls, and red-tailed hawks.
The study also discussed how higher raptor mortality occurred when smaller towers were “upgraded” with larger turbines and proportionally longer blades. These wind turbines offered what raptors perceived as intermediate to very big windows of opportunity to fly through what looked like open spaces between towers.
But actually, this space was occupied by much longer, rapidly moving rotor blades, resulting in significantly more fatalities of golden eagles, red-tailed hawks, American kestrels, burrowing owls, mallards, horned larks and western meadowlarks. Turbines with slower rotations per minute actually made it appear that there was more space and “greater windows of time.” This fooled birds, by giving them the illusion that they had open flight space between the rotating blades.
The illusion fools people, too. The newest turbines move their blades at 10–20 rotations per minute, which appears to be slow – but for their blade tips this translates into 100–200 mph!
All this was very important, because the industry was moving away from smaller turbines and installing much larger turbines, with much longer blades.
However, the industry not only ignored the APWRA findings and rapidly installed thousands of these much larger turbines across America, despite their far greater dangers for birds and raptors. It also kept the APWRA out of the public’s awareness, and focused attention on new study results that reflected far less accurate (and honest) searches and surveys.
Part II Tomorrow: Studies Deteriorate in Face of Wind Industry Pressure
Jim Wiegand is an independent wildlife expert with decades of field observations and analytical work. He is vice president of the US region of Save the Eagles International, an organization devoted to researching, protecting and preserving avian species threatened by human encroachment and development.