Effects of Decoy Gender and Wing Clipping on Capture Success of Brown-Headed Cowbirds

Due to the risks that nest parasitism by brown-headed cowbirds (Molothrus ater) pose to breeding Kirtland’s Warblers (Dendroica kirtlandii) and other songbirds, refinement of existing cowbird trapping techniques and development of new techniques are needed to improve the efficiency of cowbird removal. We conducted experiments during 1999-2002 to determine if the use of male and female decoys affected capture rates of cowbirds, and to determine if clipping primaries on one wing of female decoys to prevent escapes affected cowbird capture success. These experiments were conducted using 6 permanently placed modified Australian crow traps (decoy traps) measuring 3.6 x 3.6 x 2 m in Erie County, Ohio. Cowbirds were lured to the traps using a white millet/sunflower seed bait mixture and captive cowbirds used as decoys. To answer each question, we compared the number of male and female cowbirds captured for each trapping period among treatments at each trap using Analysis of Variance in a repeated measures design. We found no statistical effects of decoy gender or wing clipping on capture success for brown headed cowbirds. We proposed future research on trapping techniques to benefit endangered species management, management of blackbird damage in agricultural and airport situations.