Final Report: avian and bat mortality associated with the Vansycle wind project


Title: Final Report: avian and bat mortality associated with the Vansycle wind project
Publication Date:
February 07, 2000
Pages: 1-26

Document Access

Website: External Link
Attachment: Access File
(1 MB)


Erickson, W.; Johnson, G.; Strickland, M.; Kronner, K. (2000). Final Report: avian and bat mortality associated with the Vansycle wind project. pp 1-26.

The Avian Monitoring Plan for the Vansycle Wind Project located in Umatilla County, Oregon outlined a detailed protocol for estimation of bird and bat fatalities associated with the project. The Technical Advisory Committee (TAC) made up of experts from the cooperating agencies and ESI Vansycle Partners, L.P., local landowners, and representatives of Umatilla County agreed to meet after completion of one year of the monitoring program to discuss results of the monitoring studies, the evaluation of methodology, and the need for further study. This report presents results of carcass searches for the 1999 study year at the Vansycle Ridge Wind Project.


The windplant is comprised of 38 660-kilowatt Vestas turbines arranged in two strings, with 28 turbines on String A and 10 on String B. Carcass searches were conducted on half the turbines once every two weeks during the study, with all turbines searched each 28-day period. To estimate windplant mortality, the total number of carcasses found was adjusted for "length of stay" (scavenging) and searcher efficiency bias. Twelve bird and ten bat fatalities were found during the study. During searcher efficiency trials, searchers detected 50.0% of the small birds and 87.5% of the large birds. Scavenger removal trials indicated that carcasses remained on the search area for an average of 25.0 days before being removed. Based on the number of fatalities found adjusted for searcher efficiency and scavenger removal rates, the total number of turbine-related casualties in 1999 for the Vansycle Ridge Wind Project was estimated to be 24 birds and 28 bats. The fatality rate per year was estimated to be 0.63 birds/turbine and 0.74 bats/turbine. Most of the windplantrelated avian casualties on Vansycle Ridge were passerines, and many of these were likely nocturnal migrants. No raptor casualties were found during the study period. Mortality of large birds was apparently limited to chukars and gray partridge, two introduced upland gamebirds. Data collected indicate that avian and bat mortality appears to be relatively low on Vansycle Ridge. Overall results of the carcass search studies indicate that the monitoring protocol used for this study is sufficient to provide data required to adequately evaluate effects of windpower development on avian and bat resources.

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