Bird And Bat Behavior And Mortality At A Northern Iowa Windfarm
Aaftab A. Jain, 124 Science II, Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames, IA 50011; (515) 290-0533; FAX (515) 294-5468; aaftabj@iastate.edu
Rolf R. Koford, 124 Science II, Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames, IA 50011
Alan W. Hancock, Iowa Department of Natural Resources, 1203 N Shore Dr., Clear Lake, IA 50428
Guy G. Zenner, Iowa Department of Natural Resources, 1203 N Shore Dr., Clear Lake, IA 50428
We examined bird and bat mortality at a new 89-turbine windfarm constructed in an environmentally sensitive area, operational in November 2001. The windfarm is located in cropland between three Wildlife Management Areas (WMA's) with historically high bird use, and is partially encompassed by a Canada Goose (Branta canadensis) hunting refuge. Studies of bird collision mortality in California and elsewhere raised concerns about the possibility of mortalities in this area. We searched for dead birds under 26 turbines, from 15 May to 10 December, in 2003 and 2004. Six 76.2 m by 3.0 m transects were maintained vegetation-free under each turbine. We found two birds and 32 bats. Search efficiency and scavenge rates were evaluated. During search efficiency trials, 77% of bird carcasses were found. In scavenging trials, on average, <10% of carcasses were removed by scavengers within observer search cycles. We compared bird activity in fields with and without turbines using point counts. We compared bat activity using bat detectors. No significant differences were found between relative bird and bat activity at turbine, turbine with transect and non-turbine sites. Canada Goose foraging behavior was collected from crop fields in the Canada Goose hunting refuge both in and out of the windfarm. Results of goose behavioral analyses will be presented. The study will continue until December 2004. While we have yet to evaluate the significance of the mortality data, proper siting of these facilities remains a priority.