NABU recommends window markings to prevent bird collisions

According to the Nature and Biodiversity Conservation Union (NABU), approximately 100 million birds die annually in Germany due to collisions with glass panes. Birds often fail to recognize glass as an obstacle, instead flying toward reflections of trees, bushes, or the sky.

While black silhouettes of birds of prey were previously used as a deterrent, conservationists note they are largely ineffective as birds may simply fly around them. Similarly, UV markings are not specifically recommended by NABU. Instead, experts suggest using vertical lines or dot patterns to make the glass surface more visible to birds. For maximum effectiveness, these markings should be applied to the outside of the window to remain visible despite reflections.