Line color affects the collision risk and deterrence of crows

Abstract

Many techniques are used to deter birds from damaging crops, but almost all methods are impractical. Line techniques have some effectiveness and rarely result in habituation, but their mechanisms are not clear. Cost-effective and long-lasting damage control approaches are increasingly important, and thus an improved line technique that does not incur higher cost or additional labor is needed. To achieve this, this study used different colored lines (i.e., metallic wire-line and matte black wire-line) to test whether line color affects the deterrence of crows (Corvus spp.). The two colors differ in their ability to reflect the sun. Crows exhibited a higher risk of collision with the matte black wire-lines. Deterrence was also higher with matte black lines than metallic lines. Given these results, the author hypothesizes that lower visibility lines incur higher collision risk and thus have a greater deterrence effect on crows.