Oct 27 2016

Do Wind Mills “Kill All the Birds?”


No energy source is perfect, but if we are going to make rational decisions about where to invest in our energy infrastructure, we have to consider all the features of each option. We need precise information that is placed into a proper context.

That, of course, requires thoroughness, diligence, a willingness to listen to actual experts, and the ability to think somewhere above a third grade level (my apologies to all third graders).

Donald Trump apparently lacks all of those qualities.

In a recent interview Trump said:

“[Wind power] kills all the birds. Thousands of birds are lying on the ground. And the eagle. You know, certain parts of California — they’ve killed so many eagles. You know, they put you in jail if you kill an eagle. And yet these windmills [kill] them by the hundreds.”

This is a claim he has repeated in numerous speeches and, of course, late night tweets.

I know that many people consider Trump’s typical speech pattern to just be hyperbole. While it is certainly that, I am not as generous in my interpretation. His speech is undeniably scattered, imprecise, absolute, and simplistic. The most parsimonious interpretation of this fact is that his thoughts are scattered, imprecise, absolute, and simplistic.

Let’s take his claim that wind power “kills all the birds.” Of course, he doesn’t mean that wind turbines literally kill every single bird. He doesn’t mean that, but he doesn’t mean anything precise or accurate. He is satisfied with a simplistic and emotional phrase. Then he starts throwing around big numbers for emphasis, big numbers that he just makes up.

Let’s compare this to reality.

A recent review of the literature on bird deaths from wind turbines concludes that the annual death of birds in the US from wind turbines is between 140,000 and 328,000. If we extrapolate this out, then if the US increases its wind energy production to 20% of total energy, that would result in 1.4 million bird deaths per year.

Before we go on, I want to point out that I am an avid birder. I love birds, and would prefer that we take all reasonable measures to preserve our native bird species. I am concerned about the adoption of a new technology that will increase the annual death of native birds. So don’t think I am taking the issue lightly.

I should add that windmills are perhaps an even greater hazard to bats, of which I am also a fan.

But here is where knowing the precise numbers, and being able to think through an issue, is necessary to have a meaningful opinion. Let’s compare bird deaths from wind turbines to bird deaths from other sources.

Cell towers kill an estimated 6.8 million birds annually. That is 20 times the current death rate from wind turbines, and about five times greater than even a fully deployed wind energy infrastructure.

High tension wires kill about 200 million – that is about 1,000 times as many birds as wind turbines.

But we’re just getting started. Windows are the big technological killer of birds. Between 365 and 988 million birds are killed each year from collisions with windows. I wonder how many birds Trump’s hotels and other buildings kill.

We haven’t even mentioned the biggest bird killer of them all – cats. A 2012 meta-analysis concluded:

We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually.

Of course, no study is final, and this study has come under some criticism, but let’s assume their estimate is not off by more than an order of magnitude.

Even if we take the lower end of the estimate ranges for each of these other sources of bird deaths, they add up to 1,872 million bird deaths a year in the US. If we compare this to the upper range of the estimate for wind turbines, 1.4 million per year after full deployment, we can see that what Trump referred to as “killing all the birds” amounts to little more than a round off error in estimates of bird deaths.

The chart at the top of this post comes from Sibley Guides. As you can see graphically, wind power deaths barely register as a blip on this chart.

What about those bald eagles? Even a small total number of bald eagle deaths is a concern. Estimates are very loose at this point, but the present estimate is that 100 golden eagles (not bald eagles) are killed per year in the US by wind farms. There have been only 6 confirmed bald eagle deaths due to wind turbines in the last 20 years. That is certainly an underestimate because these were incidental findings, not systematic searches.

Of course we should also consider the effects of climate change on bird species, although that will be a thorny and controversial issue. It is not unreasonable to conclude, however, that it is possible wind power may save more birds than they kill to the extent that they mitigate climate change. I will only say “possible” because that will be very difficult to estimate.

What about other sources of power? What is the effect of pollution from coal burning plants on bird populations?

Even if we set aside the unknowns, bird deaths from wind turbines is minuscule compared to other sources. If we truly care about the birds, we would promote technologies to mitigate deaths from collisions with windows and bury our power lines. You should also keep your cats indoors, and help control feral cat populations.

I also favor exploring technologies to reduce bird and bat deaths from wind turbines. One study, for example, found that if wind turbines turned on at higher wind speeds that would reduce energy production by only 1% but slash bat deaths (and possibly bird deaths). We need to consider where we put them, and explore technologies to repel birds and bats from the blades.

None of these technologies will save more birds than putting stickers on windows, but we should do them also.

This is the kind of thorough and nuanced discussion that we need from our elected leaders. They need to make practical decisions that consider all outcomes and alternatives, that are well-informed by experts, and are reasonably evidence-based. I don’t expect a nuanced discussion during a campaign speech, but a minimally accurate one would be nice.

Unlike some of his defenders, I don’t think Trump is dumbing it down for his campaign speeches or tweets. All of the evidence points to the conclusion that we are seeing the extent of his thought processes, and the nonsensical conclusions to which they lead.

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