Mark A. Hayes. Bats Killed in Large Numbers at United States Wind Energy Facilities. BioScience, 2013
See also:
Wind turbines fiasco: the news from Germany — Dr Bittar, 2013.10.13
Summary from:
http://www.sciencedaily.com/releases/2013/11/131108091314.htm
High Bat Mortality from Wind Turbines
Nov. 8, 2013 —
A new estimate of bat deaths caused by wind turbines concludes that more than 600,000 of the mammals likely died this way in 2012 in the contiguous United States. The estimate, published in an article in BioScience, used sophisticated statistical techniques to infer the probable number of bat deaths at wind energy facilities from the number of dead bats found at 21 locations, correcting for the installed power capacity of the facilities.
Bats, although not widely loved, play an important role in the ecosystem as insect-eaters, and also pollinate some plants. They are killed at wind turbines not only by collisions with moving turbine blades, but also by the trauma resulting from sudden changes in air pressure that occur near a fast-moving blade.
The article by Mark Hayes of the University of Colorado notes that 600,000 is a conservative estimate; the actual figure could be 50 percent higher. The estimate is in rough agreement with some previous estimates, but bigger than most. The data that Hayes analyzed also suggest that some areas of the country might experience much higher bat fatality rates at wind energy facilities than others: the Appalachian Mountains have the highest estimated fatality rates in Hayes’s analysis.
The consequences of deaths at wind energy facilities for bat populations are hard to assess because there are no high quality estimates of the population sizes of most North American bat species. But Hayes notes that bat populations are already under stress because of climate change and disease, in particular white-nose syndrome. The new estimate is therefore worrisome, especially as bat populations grow only very slowly, with most species producing only one young per year.
A recent study 3/7/13 from Germany … http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0067997#pone-0067997-t004
the authors estimate that the annual deaths are 4.5 bat death PER YEAR per turbine.
“These estimates are in line with other studies in Central and Western Europe. For example, [35] obtained an estimate of 6 to 26 bats killed annually per turbine in France and a review on bat mortality for north-western European countries came up with 0 to 20 bats killed annually per turbine [15]. ”
If we are considering a couple of turbines for the island, I wonder if more than ten or so bats per year are killed by cars or other sources. Let’s get some wind turbines here!
Thank you Nelly for the useful link.
From my understanding of the article, the 4.5 number of deaths is not for a year, but for a 100-day period:
“(…) mean was 4.5 in the data sets with 100 days per turbines [sic]”
which is confirmed elsewhere with the authors stating (they use a number of statistical methods):
“We estimated an average of 0.05 to 0.08 bats killed per turbine and night.”
That means the mean number of deaths that can be inferred from an analysis of carcasses near the turbines is actually 16-29 per year, not 4.5 (one must take on board that bats on Kangaroo Island are active every one of the 365 nights in the year).
It’s a complex article though, and I might be wrong in my understanding of it.
But these numbers are in congruence with the other German study mentioned at “Bats die massively at wind farms — Voigt et al. 2012”
Please note that most death from the turbines are due not to direct hits with the blades but through barrotraumas (the inner organs and lungs of bats are lethally damaged when bats are exposed to rapid pressure reductions behind the blades). These bats mostly die at some distance from the turbines, and these deaths basically are not taken into account.
Please note also this is an average, with wind turbines differing greatly in size. The number of deaths obviously does not increase linearly with the size of the wind turbines, the largest wind turbines having in all likelihood a disproportionate impact on bats.
And it’s the giant model that has been discussed for Kangaroo Island.
Since most bat species produce only one young per year, a regular attrition rate of many dozens of bats each year would in the long term have quite a detrimental impact on their population on the island.
PS
I doubt car collisions are an important cause of deaths of bats on the island. In 14 years, I have never seen the corpse of a bat hit by a car. And I never heard of it, personally.
While the National Renewable Energy Laboratory is an industry group, they show that there is little likelihood that a 1.4kPa event from a 1.5mW turbine could be fatal.
http://www.nrel.gov/wind/news/2013/2149.html
You state “the largest wind turbines having in all likelihood a disproportionate impact on bats”. I believe that is correct but possibly only for migrating bats which are flying at higher altitudes.
Again, the real point is that the annual number of deaths per turbine is small.
http://www.bio.ucalgary.ca/contact/faculty/pdf/barclay/Barclay07Tur.pdf
Locating of the turbines can surely take into account whether bats are naturally present or not in the area in order to mitigate turbine damage.
See also:
Comparing bird and bat fatality-rate estimates among North American wind-energy projects. KS Smallwood. Wildlife Society Bulletin, Volume 37, 2013.
http://onlinelibrary.wiley.com/doi/10.1002/wsb.260/abstract
Abstract
Estimates of bird and bat fatalities are often made at wind-energy projects to assess impacts by comparing them with other fatality estimates. Many fatality estimates have been made across North America, but they have varied greatly in field and analytical methods, monitoring duration, and in the size and height of the wind turbines monitored for fatalities, and few benefited from scientific peer review. To improve comparability among estimates, I reviewed available reports of fatality monitoring at wind-energy projects throughout North America, and I applied a common estimator and 3 adjustment factors to data collected from these reports. To adjust fatality estimates for proportions of carcasses not found during routine monitoring, I used national averages from hundreds of carcass placement trials intended to characterize scavenger removal and searcher detection rates, and I relied on patterns of carcass distance from wind turbines to develop an adjustment for variation in maximum search radius around wind turbines mounted on various tower heights. Adjusted fatality rates correlated inversely with wind-turbine size for all raptors as a group across the United States, and for all birds as a group within the Altamont Pass Wind Resource Area, California. I estimated 888,000 bat and 573,000 bird fatalities/year (including 83,000 raptor fatalities) at 51,630 megawatt (MW) of installed wind-energy capacity in the United States in 2012. As wind energy continues to expand, there is urgent need to improve fatality monitoring methods, especially in the implementation of detection trials, which should be more realistically incorporated into routine monitoring.
http://au.ibtimes.com/articles/533691/20140110/kangaroos-australia-heat-wave-global-warming-winton.htm#.UtHXoChe-To
100,000 bats die in Queensland due to heat wave.
“Australian Bureau of Meteorology Climate Monitoring Manager Karly Braganza stated global warning as another contributing factor to the ongoing heat wave. ” What is worse in the long run?