As wind farms populate large expanses of land of low and medium human-population density, the large-scale slaughter of birds and bats is staggering.
By K. Shawn Smallwood
First published: 26 March 2013
DOI: 10.1002/wsb.260
Wildlife Society Bulletin , Volume 37, Issue 1, March 2013, Pages 19–33
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. © 2013 The
Wildlife Society
