Circular-shaped decals prevent bird-window collisions

Millions of birds die every year from collisions with glass panes worldwide. These estimates are still scarce in the tropics, and more studies are needed to evaluate the effectiveness of preventive measures. We compared the efficacy of two methods to prevent bird-window collisions: birds of prey vs. circular decals (BPD and CD, respectively), contrasted to glass panes without any intervention. We estimated bird-window collisions in four buildings, two twin buildings with CD treatment proportionally interspersed with no decals glass panes, and two BPD-treated buildings with proportionally control area without any device. We recorded 14 collisions from nine species, mostly Columbina talpacoti (4) and Tangara sayaca (3). The highest number of collisions was against glass windows with no intervention (9; 64%), followed by those with BPD (5; 36%). No accidents were recorded against glass panes with CD. Our data may support that circular decals are more efficient than BPD to prevent bird-window collisions.