Possible eagle avoidance at wind farms

[Chris Merkord]

Golden Eagle Soaring A golden eagle soars over Seedskadee NWR. Photo Credit: Tom Koerner/USFWS. Source: Flickr

From the Birding Community E-bulletin, May 2014:
 
POSSIBLE EAGLE AVOIDANCE AT WIND FARMS
 
A trio of researchers at the University of Northern British Columbia observed a total of 1,134 Golden Eagles over three fall migration seasons at the location of a new wind farm, both before and after the construction of the site. The first year was pre-construction followed by two years of post-construction data-gathering.
 
In the first year, there were 60 flights, with 20 flights through the future "risk zone" (the position where a blade strike could occur, if there were one). In the next two years, only nine of 148 flights across the ridge-top flew through the "risk zone," which represented a significant drop. Moreover, Golden Eagles seemed to avoid the danger zone even more when the wind was up, thus offering plenty of clearance for turbine blades to spin. Following construction, only three of nine risky trips happened when the wind speed was sufficiently high. In general, the eagles flew high enough to clear the blade-sweep when wind conditions were significant.
 
In general, these Golden Eagles seemed to show a degree of detection and avoidance of turbine-blade zones during migration.
 
Of course, these results do not absolve wind power entirely when it comes to threats to bird strikes. The British Columbia study only pertains to circumstances involving one location and one diurnal migrant species - Golden Eagle. These results do suggest however that the siting of wind farms in certain pathways may have less of an impact than might otherwise be expected. The researchers were quick to point out that wind farms placed where birds are more likely to remain for extended periods (e.g., breeding and wintering areas) might still present real problems.
 
You can access the researchers' full paper from PLoS One here:
www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0093030#abstract0