(Maybe worth emphasizing this is Brian writing, not Eli or John.)
A new study gives some reason to believe that wind turbines have secondary effects on bat mortality compared to other anthropogenic factors like intentional killing, accidents, and the imported fungal disease called White Nose Syndrome. You'd have trouble knowing that though after reading the
bad reporting in Scientific American and
worse Op-Editing by a Manhattan Institute 'scholar'. To be fair to the secondary reports, the study itself could've done a better job discussing its results.
Disclaimer time! I'm not a scientist, let a alone a bat specialist, maybe I'm off. Regardless, said specialists probably will get something useful from the study, but it's broader public effect isn't so great.
So, problems with the study:
1. It is not a study of bat mortality. It's a study of Mass Mortality Events (ten bodies or more). If you don't know the relationship between MMEs and overall mortality (and apparently we don't), then you don't know the importance of MME causes to bat conservation. Aside from one throwaway sentence (that many bat species are gregarious and therefore likely to have MMEs) this issue isn't discussed. There's also no discussion of habitat destruction except when the destruction creates MMEs, when habitat destruction is likely far more important than any other factor.
2. Actually, it's not a study of MMEs, it's a study of reported MMEs. In other words, nobody went out and did transects in places with bats to survey for MMEs - this study just looks at reports of MMEs however they came to be, creating a significant bias because what gets reported is not even an attempt at a random survey of MMEs. This is not well-acknowledged in the study, with an important exception saying wind turbine reports are biased higher because of mandatory reporting requirements that don't exist for other causes. Subsequent reporting on this study by others omits this disclaimer.
3. Worst of all IMHO is they included qualitative reports of MMEs (i.e. reports of "many" dead bats) and they did not adjust measured mortality quantitatively for the number of deaths in each MME. So a MME of 10 bats counts equally in their study with one killing 10,000 bats (and they acknowledge some MMEs at that level and higher). I think this is worst of all because it seems like something they could actually fix, while the first two problems are limitations they couldn't fix but could have acknowledged more readily.
Related to this last flaw of what MMEs were considered is that they excluded MME reports of food markets and of bat imports. My cynical take is they excluded those categories because they'd overwhelm the others and highlight the problem of selection bias for reported MMEs. They say they excluded food market reports because it's been studied elsewhere, an explanation that doesn't make sense when surveying relative causes of mortality.
Disclaimer time again! I didn't read the supplements which might give some defense against my criticism, but they weren't attached to the Google Scholar link. I supposed I could've been more industrious and contacted the authors, but I also think these flaws should've been addressed in the study itself.
Anyway, some props to the study for disclosing its limitations even if they could've highlighted them and done things differently. Below are the key category results IMO - they disclose and then ignore the figures in parentheses, we will do the opposite (and note the study includes other categories that aren't relevant to this post):
Category Total MMEs (and order of magnitude for maximum number carcasses in single events per category)
Intentional killing 205 (10x5)
Accidental 66 (10x4)
Wind turbines 281 (10x2)
White Nose Syndrome 266 (10x4)
What I take from this is that of these four categories, wind turbines kill the fewest bats - by two or more orders of magnitude. Contrast this with the study abstract that says
Collisions with wind turbines and white-nose syndrome
are now the leading causes of reported MMEs in bats.
Scientific American takes that to mean
wind turbines are, by far, the largest cause of mass bat mortality around the world
And Robert Bryce of the Manhattan Institute:
wind turbines are now the largest cause of mass bat mortality.
People who don't read the original study (Bryce doesn't even link to it) are unlikely to catch the importance of the qualifier "mass," or that they're measuring events and not the numbers of bats killed in mass events. Even with all that, Scientific American's "by far" is completely wrong. Bryce gets many other things wrong or exaggerated in his anti-wind jeremiad.
One wrinkle to this is that the study shows a large change in MMEs since 2000, with far fewer of other categories while nearly-identical, large numbers of MMEs occur from wind turbines and White Nose Syndrome (maybe 37% of events from turbines and 36% from WNS). That still doesn't change the fact that WNS kills bats by two orders of magnitude more, nor that there's a reporting bias to show more wind turbine MMEs.
I'm not rejecting that turbines killing bats are a concern (my idea btw is to put high-frequency, very short distance sonar warning noisemakers on problematic turbines), just how it's being discussed. The study does mention climate change as a future and present-day impact on bats. Bryce somehow omits that.
What this all needs is perspective.