Wind farms and abuse of statistics: bird edition

When "wind farms are dangerous" really just means "there are a lot of birds".

When dealing with large numbers, it helps to have an idea of the expected order of magnitude. That way, you can know whether it is merely the number which is large, or the thing it's describing as well.

For instance, if I tell you of a country with 140,000 people in long-term unemployment, it's rather important for you to know if I'm talking about the US (population 280 million) or Luxembourg (population 525,000).

That's a test a Spectator article, Wind farms vs wildlife, failed quite badly this week.

The author, Clive Hambler, is a lecturer in biological and human sciences at Oxford university, and quotes a number of statistics to demonstrate how dangerous wind farms are to wildlife. For instance:

Every year in Spain alone — according to research by the conservation group SEO/Birdlife — between 6 and 18 million birds and bats are killed by wind farms. They kill roughly twice as many bats as birds. This breaks down as approximately 110–330 birds per turbine per year and 200–670 bats per year. And these figures may be conservative if you compare them to statistics published in December 2002 by the California Energy Commission: ‘In a summary of avian impacts at wind turbines by Benner et al (1993) bird deaths per turbine per year were as high as 309 in Germany and 895 in Sweden.’

Similar claims are made throughout. Apparently the annual death toll of bats in the US and Canada is "up to three million", "Norwegian wind farms kill over ten white-tailed eagles per year", and so on.

What is missing is any context through which we can examine these numbers. It might change our interpretation of the figures to know that:

Domestic and feral cats have also been considered a major source of anthropogenic-caused mortality with estimates near 100 million annual bird deaths [in the US].

Or that, on roads near wetlands in Canada:

223 birds were killed per mile per year.                                                                                            

Power lines in the US are estimated to kill:

…approximately 130 million birds per year.                                                                                                        

While we're banning things, we may want to keep an eye out for that scourge of the avian world, windows:

97.6 to 976 million bird deaths per year in the U.S. due to collisions with windows… based on an estimated 1 to 10 bird deaths per structure per year from a fatality study in New York.

All those figures come from a 2005 paper by the US Department of Agriculture.

In other words, even with the massive figures from Spain – figures which show deaths per turbine per year two orders of magnitude higher than equivalent figures cited in the above paper, which are based on an assumption that for every confirmed death, there's nineteen uncomfirmed, and which come from a set of guidelines which explicitly concludes wind farms are OK for birds if built correctly (pdf) –  wind farms kill fewer birds than cats, power lines, roads or windows. That comparison would have been rather useful to include in the original piece. With that in mind, the numbers in the piece become less a demonstration of the awesome mortality of wind farms, and more a confirmation that yes, there are a lot of birds in the world.

Update

It's been pointed out on Twitter that I'm not comparing like to like. Spain is smaller than the US, of course. Thankfully, the USDA also estimates the number of birds killed by wind farms in America: between 20,000 and 37,000 a year. I let you draw your own conclusions from the discrepancy.

Wind Turbines in Spain. Photograph: Wikimedia Commons

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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A small dose of facts could transform Britain's immigration debate

While "myth-busting" doesn't always work, there is an appetite for a better informed conversation than the one we're having now. 

For some time opinion polls have shown that the public sees immigration as one of the most important issues facing Britain. At the same time, public understanding of the economic and social impacts of immigration is poor and strongly influenced by the media: people consistently over-estimate the proportion of the population born outside the UK and know little about policy measures such as the cap on skilled non-EU migration. The public gets it wrong on other issues too - on teenage pregnancy, the Muslim population of the UK and benefit fraud to name just three. However, in the case of immigration, the strength of public opinion has led governments and political parties to reformulate policies and rules. Theresa May said she was cracking down on “health tourists” not because of any evidence they exist but because of public “feeling”. Immigration was of course a key factor in David Cameron’s decision to call a referendum on the UK’s membership with the EU and has been central to his current renegotiations.  

Do immigration facts always make us more stubborn and confused?

The question of how to both improve public understanding and raise the low quality of the immigration debate has been exercising the minds of those with a policy and research interest in the issue. Could the use of facts address misconceptions, improve the abysmally low quality of the debate and bring evidence to policy making? The respected think tank British Future rightly warns of the dangers associated with excessive reliance on statistical and economic evidence. Their own research finds that it leaves people hardened and confused. Where does that leave those of us who believe in informed debate and evidence based policy? Can a more limited use of facts help improve understandings and raise the quality of the debate?

My colleagues Jonathan Portes and Nathan Hudson-Sharp and I set out to look at whether attitudes towards immigration can be influenced by evidence, presented in a simple and straightforward way. We scripted a short video animation in a cartoon format conveying some statistics and simple messages taken from research findings on the economic and social impacts of immigration.

Targeted at a wide audience, we framed the video within a ‘cost-benefit’ narrative, showing the economic benefits through migrants’ skills and taxes and the (limited) impact on services. A pilot was shown to focus groups attended separately by the general public, school pupils studying ‘A’ level economics and employers.

Some statistics are useful

To some extent our findings confirm that the public is not very interested in big statistics, such as the number of migrants in the UK. But our respondents did find some statistics useful. These included rates of benefit claims among migrants, effects on wages, effects on jobs and the economic contribution of migrants through taxes. They also wanted more information from which to answer their own questions about immigration. These related to a number of current narratives around selective migration versus free movement, ‘welfare tourism’ and the idea that our services are under strain.

Our research suggests that statistics can play a useful role in the immigration debate when linked closely to specific issues that are of direct concern to the public. There is a role for careful and accurate explanation of the evidence, and indeed there is considerable demand for this among people who are interested in immigration but do not have strong preconceptions. At the same time, there was a clear message from the focus groups that statistics should be kept simple. Participants also wanted to be sure that the statistics they were given were from credible and unbiased sources.

The public is ready for a more sophisticated public debate on immigration

The appetite for facts and interest in having an informed debate was clear, but can views be changed through fact-based evidence? We found that when situated within a facts-based discussion, our participants questioned some common misconceptions about the impact of immigration on jobs, pay and services. Participants saw the ‘costs and benefits’ narrative of the video as meaningful, responding particularly to the message that immigrants contribute to their costs through paying taxes. They also talked of a range of other economic, social and cultural contributions. But they also felt that those impacts were not the full story. They were also concerned about the perceived impact of immigration on communities, where issues become more complex, subjective and intangible for statistics to be used in a meaningful way.

Opinion poll findings are often taken as proof that the public cannot have a sensible discussion on immigration and the debate is frequently described as ‘toxic’. But our research suggests that behind headline figures showing concern for its scale there may be both a more nuanced set of views and a real appetite for informed discussion. A small dose of statistics might just help to detoxify the debate. With immigration a deciding factor in how people cast their vote in the forthcoming referendum there can be no better time to try.