Laboratory efficacy of an anthraquinone-based repellent for reducing bird damage to ripening corn

Abstract

Wildlife repellents provide a non-lethal alternative for managing agricultural impacts associated with wildlife depredation. To evaluate a potential bird repellent for ripening corn, we conducted a feeding experiment at the United States Department of Agriculture, National Wildlife Research Center with 66 red-winged blackbirds (Agelaius phoeniceus). Using a two-choice experimental design we tested the efficacy of Avipel repellent (a.i. 50% 9,10-anthraquinone) on ripening sweet corn. Red-winged blackbirds consumed an average of 8.6%±0.9% of kernels from untreated ears and 5.3%±1.1% from ears treated with anthraquinone. The interaction between anthraquinone concentration and corn treatment suggests a positive concentration-response for red-winged blackbirds. Odds ratio analysis suggests red-winged blackbirds were 1.4 times more likely to damage untreated sweet corn compared to treated sweet corn. These results suggest efficacy of anthraquinone-based products as red-wing blackbird repellents for ripening corn. Moreover, exposure to anthraquinone-based repellents may reduce consumption of a food matrix that receives little to no direct anthraquinone exposure. Supplemental research is recommended to evaluate anthraquinone-based repellents under field conditions, including the establishment of a chemical tolerance for food and feed use.