Tilting at windmills

RSPB Scotland Senior Conservation Policy Officer, Richard Evans' response to Daily Telegraph article.

Tilting at windmills

According to yesterday’s Daily Telegraph, "wind turbines have killed more birds of prey than persecution this year", in Scotland.  Well, to quote the hapless William Boot in Evelyn Waugh’s journalistic satire Scoop:  “Up to a point, Lord Copper”. 

The Telegraph piece is based on statistics released this week by SASA (the Scottish Government’s providers of Science and Advice for Scottish Agriculture)[1].

The new figures cover the first two quarters of 2014, and include for the first time details of all animals submitted to SASA, as opposed to only incidents involving pesticides. On the face of it, this looks like an opportunity to make the sort of comparison reported by the Telegraph.  But does it?

Well, probably not to the extent to which the article implies.

First of all, SASA clearly state that “... due to the nature of some incidents and the investigations relating to these it may be necessary to limit the information published.  We will publish updates to such cases as further information becomes available ....”  Some of the information that has been “limited” relates to the 22 birds of prey found dead in March and April 2014 on the Black Isle, fifteen of which Police Scotland in June “confirmed as having digested an illegally-held poisonous substance”. The police later confirmed that a further victim has tested positive for the same substance. The SASA spreadsheet covers these birds with a single row, listing the “species or sample involved” as “various”, alongside the comment “This incident is the subject of an on-going investigation”.  So, the Telegraph’s analysis inadvertently omits sixteen bird deaths resulting from an illegal act or acts –meaning that in the first half of 2014, at least four times as many birds of prey were found to have died in Scotland as a consequence of wildlife crime than as a result of colliding with wind turbines.

Secondly, there is a more fundamental question of whether data such as SASA’s can be used to compare the rate of different causes of bird death at all.  Most wildlife crime goes unreported, and if carcasses are recovered at all they are often in such a poor state that the cause of death cannot be determined. By contrast, accidental deaths are much more likely to reported – and quickly enough for a post-mortem to be carried out. This difference introduces a statistical quirk, technically known as selection bias, meaning that a simple comparison of the numbers of different known causes of death is likely to be flawed.

In common parlance, the Telegraph piece compares apples and carrots.  Yes, the SASA data includes four bird of prey deaths at windfarms (apples).  Yes, the SASA data includes two bird of prey deaths from persecution (carrots).  Are there twice as many wind turbine deaths of Scottish raptors as deaths resulting from illegal killing?  Err, no – because selection bias means that turbine deaths (apples) are far more visible than deaths resulting from persecution (carrots), and the SASA data reports only on birds found and submitted for analysis.  And, err no again – because SASA clearly state that the data for the period are incomplete. 

It is unfortunate  that the ever-defensive Scottish Gamekeepers Association jumped on this decidedly shaky bandwagon, in a bid to try to exonerate an increasingly beleaguered gamebird shooting industry from any involvement in raptor persecution, despite contrary evidence being found on sporting estates year after year after year, and the monotonous regularity of gamekeepers appearing in our courts, including a case just last week.

But if you’re still not convinced that the Telegraph piece is way wide of the mark, why not try this little thought experiment?  Suppose – just suppose – you wanted to rid a landscape of its birds of prey, how would you do it?  Would you build a new-fangled and expensive wind farm, in the hope that all those eagle-eyed, highly manoeuvrable birds of prey would, like moths to a flame, fly into the turbines?   Or would you rely on the tried and trusted Victorian methods of targeted trapping, shooting, poisoning and nest destruction that continue to be used by some to eradicate some of our rarest bird of prey species from vast swathes of our uplands?

This is not to say that there is no risk to birds of prey from windfarms.  However, by and large the renewables industry is keen to minimise damage; and the consenting process for wind turbines is geared to avoid it.  Wish that we could say the same about some elements of the shooting industry.