A Meta-Analysis of Bird-Window Collision Solutions

Abstract

North American bird populations are declining and bird-window collisions are a leading cause, resulting in 365 - 988 million bird deaths each year in the U.S. alone. One approach aimed at reducing these collisions is treating windows to reduce reflectiveness. To address the lack of comparisons between window treatments, my goal was to use a meta-analytic approach to evaluate window treatments. Specifically, the objective was to account for the variation between studies and quantify an overall effect of applied treatments, effect and rank of individual treatments, and effect and rank of treatment characteristics. I reviewed the literature following PRISMA guidelines and used meta-analysis to evaluate data across studies. I used rate ratios to compare collision rates of treated windows to clear glass for an overall estimate of effectiveness, as well as estimate for individual treatments and treatments grouped by characteristics. Overall, all treatments included in the study resulted in ~80% reduction in rate of collisions compared to clear glass. Individual treatments that performed best were complete coverage of the window with a UV absorbing and reflecting pattern (CPFilms, Fieldale, Virginia, USA) and complete coverage with white CollidEscape (Janesville, Wisconsin, USA). Assessment of treatment characteristics suggests extensive patterning and contrast are important for bird-window collision solutions to be extremely effective. Application of treatments to existing windows provide a benefit to birds and feasible solutions are available for homes and businesses.