Birds hit windows because of the reflections caused by sunlight hitting windows. This causes birds to fly into windows instead of what they think is a tree, sky, or open habitat. By breaking up the reflections with anything following the 2-inch-by-4-inch rule, birds are less likely to strike the window. The 2-by-4 rule refers to the space between horizontal elements at no more than 2 inches apart, and the space between vertical elements at no more than 4 inches apart.
This can be done a few different ways, including:
- Applying patterned window films, decals, or tapes
- Hanging cord or rope, spaced 4 inches apart, in front of windows - Acopian BirdSavers
- Using bird-friendly glass - birdsmartglass.org
- Using exterior screens
- Placing bird feeders and birdbaths either within 3 feet or beyond 35 feet