Dogs, Birds, Bats, and the Shoenfeld Estimator

By John McFerrin

            For various reasons operators of industrial wind turbines seek to know the number of birds and bats that are killed by the turbines.  Some studies are done as part of academic research; some are done to meet some regulatory or permitting requirement; some are done as part of studies to make the turbines less harmful to birds and bats.

            Such studies typically involve a researcher going to the base of the wind turbine and walking around the base of the turbine in ever larger circles, collecting bird and bat carcasses.  These are then sorted by species, counted, and catalogued.  The result is the first step in determining how many birds or bats perished.

            The difficulty is that the number of carcasses recovered is never equal to the number of birds or bats that perished.  It is inevitable that some will fall in tall weeds and never be discovered by researchers.  Some will be carried away by scavengers.  There will always be fewer found than actually died.

            This is where the Shoenfeld Estimator comes in.  It is a mathematical technique in which one can take the number of bird and bat carcasses recovered and, using the Estimator, accurately estimate the number of birds and bats actually killed. 

            While few may recognize the Shoenfeld Estimator, many will recognize the name of its inventor, former West Virginia Highlands Conservancy Board member Peter Shoenfeld.  He invented it in 2004 as part of our advocacy around the Backbone Mountain wind farm.  It is now widely accepted by academics and consultants who want to know how many birds or bats perished at an industrial wind turbine.

            Now there is a new development that may require some adjustments of the Shoenfeld Estimator: dogs.  

            Dogs are now being used to find the carcasses of bats and birds killed by industrial wind turbines.  What was once a long day of drudgery for human researchers is now a game of fetch for specially trained dogs.  

            Anyone who has ever played fetch with a dog until their arm was about to drop off knows the canine temperament necessary for this job.  Even though they get to work for an hour and then rest for an hour, it still takes enormous energy to find and retrieve bats and birds.  For dogs with the right temperament, it is a great job, playing fetch to their heart’s content.

            It turns out that dogs are incredibly good at patrolling windfarms and finding dead birds and bats.  There are estimates of their effectives that range as high as 96%, many times better then human researchers.

            The Atlantic had a story about this.  If you want to read more, go to  There was no mention of the adjustments that may have to be made to the Shoenfeld Estimator.