Sticking one or two decals on a window will not help. You might try one of these techniques, ranked roughly from most to least effective: Cover the glass on the outside with window screening or netting at least 2–3 inches from the glass, taut enough to bounce birds off before they can hit the glass.

Window Alert is a static-cling decal that may be applied to home and office windows, helping birds "see" windows and thus avoid striking the glass. The decal contains a component which brilliantly reflects ultraviolet sunlight. This ultraviolet light is invisible to humans, but glows like a stoplight for birds.

Ultraviolet (UV) decals and dabbers This warrants them completely ineffective at night when most birds migrate and during early morning and evening hours. Similar to the birds of prey decals, UV-based decals and dabbers must also be applied close together in a dense pattern to effectively deter avian species.