Birds are one of the most important species in our ecosystem, and they face a major threat from window collisions. Each year, millions of birds die after crashing into windows on buildings, transportation shelters, noise barriers, and fences. While public awareness of bird-window collisions has grown in recent years due to surveys for dead birds beneath windows, there are still major gaps in understanding how and why birds fly into windows, and what happens to the birds afterwards.
Understanding Bird Window Collisions
One of the primary causes of bird window collisions is the reflection of trees or sky on glass surfaces. These reflections can confuse birds into thinking that there is an opening in the window that they can fly through. However, it is difficult to observe these collision events directly because they happen so quickly. To better understand this phenomenon, researchers have studied bird flight velocity prior to impact as a predictor for lethality. This research has led to recommendations that bird attractants (feeders or baths) should be placed close to windows (within 1.5 feet or 0.5 m) to reduce the available space where birds can gain speed before colliding with a window.
Designing New Buildings Based on Practices That Limit Risk
New buildings can also be designed based on practices that limit risk of bird window collisions. For example, windows with low reflectivity are less likely to cause confusion for passing birds than those with high reflectivity; frosted glass or etching patterns on glass surfaces can help reduce reflections significantly. Additionally, vertical stripes around windows have been found to be effective at reducing bird strikes; wider stripes and thicker lines are more visible to birds than thin lines or narrow stripes as well as being more aesthetically pleasing than heavy mesh covers over windows. Finally, there are some plants that naturally repel birds such as lavender and marigolds—planting these near windows could help reduce window collisions further.
Bird window collisions pose a major threat to global avian populations each year. By understanding how and why birds fly into windows as well as what happens afterwards we can make informed decisions about how best to prevent these deadly events from occurring in future by placing bird attractants close to windows (within 1.5 feet or 0.5 m) and designing new buildings based on practices that limit risk of bird-window collisions including using frosted glass or etched patterns on glass surfaces as well as vertical stripes around windows with wider stripes and thicker lines being more visible than thin lines or narrow stripes for both aesthetic purposes and visibility for passing birds alike. Ultimately by taking proactive action now we can help protect our precious avian population from further harm now and in future generations too.
