Winter bird-window collisions: mitigation success, risk factors, and implementation challenges

Area of Science:

• Ornithology
• Urban Ecology
• Conservation Science

Background:

• Bird-window collisions pose a significant threat to avian populations, causing millions of fatalities annually in the United States.
• Existing research often lacks pretest and posttest evaluations of mitigation strategies on real-world building structures.
• Mirrored windows and proximity to certain fruiting trees have been anecdotally linked to increased collision risk.

Purpose of the Study:

• To evaluate the efficacy of a bird deterrent film (Feather Friendly®) in reducing bird-window collisions on an existing building.
• To assess the impact of mirrored windows and proximity to fruiting pear trees on collision rates.
• To investigate the potential of bird-friendly glass designs in mitigating collisions.

Main Methods:

• A pretest-posttest design was employed, monitoring collisions on a mirrored building facade before and after the application of bird deterrent film.
• Collision data were collected over two winter seasons (Winter 1 and Winter 2).
• Expanded monitoring across eight buildings examined risks associated with mirrored windows, pear trees, and the benefits of bird-friendly glass, alongside citizen science data collection.

Main Results:

• Application of bird deterrent film reduced collisions by 71% in the treated area (from seven to two).
• The control area showed no reduction in collisions (eight in both seasons).
• Mirrored windows and proximity to fruiting pear trees were associated with higher collision odds, while bird-friendly glass showed a promising, though not statistically significant, reduction in collisions.

Conclusions:

• Bird deterrent film is an effective mitigation strategy for reducing bird-window collisions on existing buildings.
• Building design elements like mirrored facades and landscape choices (e.g., fruiting trees) significantly influence bird collision risk.
• Further research and implementation of bird-friendly glass and other deterrents are crucial for avian conservation in urban landscapes.