A Silent Threat: Bird Window Collisions & How to Prevent Them

A Silent Threat: Bird Window Collisions & How to Prevent Them

After a review of an article by the U.S. Fish & Wildlife Service titled “Reducing Bird Collisions With Buildings and Building Glass Best Practices” we chose to write an article that looks into bird window collisions and how window films might play a role in helping reduce this problem.

Birds, with their vibrant plumage and melodious songs, enrich our lives in countless ways. Yet, a hidden danger lurks in our modern world – glass windows and reflective surfaces. Birds simply don’t perceive clear or reflective glass as a barrier, leading to a tragic phenomenon: bird window collisions.

What Causes Bird Window Collisions?

A Silent Threat: Bird Window Collisions & How to Prevent Them - 2During the day, the peak risk period, birds see reflections in the glass. These reflections can be anything from clouds and sky to vegetation or even the ground, creating an illusion of open space. Alternatively, they might see right through the glass, mistaking the interior for actual habitat, especially if there are potted plants nearby.

Nighttime presents a different set of challenges. During migrations, particularly in spring and fall, birds can be drawn to brightly lit buildings. This attraction can lead to collisions, entrapment, and even exhaustion due to excessive energy expenditure. The consequences are stark – concentrated avian mortality events have been documented near buildings, communication towers, and offshore platforms, all thanks to the allure of artificial lights in otherwise dark environments.

The estimated annual bird mortality in the US from window collisions is staggering: between 365 and 988 million birds. While many envision this problem solely related to towering skyscrapers, the reality is quite different. A significant portion, 56%, of bird-window collisions occur at low-rise buildings (4-11 stories), with 44% happening in both urban and rural residences. High-rises contribute less than 1% to the overall mortality rate.

There is hope, however. The US Fish and Wildlife Service’s Division of Migratory Bird Management has compiled a valuable list of best practices and technologies to reduce bird collisions with building glass. These practices are categorized for both residences and office buildings, and cater to both new constructions and existing structures undergoing renovation or retrofitting. Notably, many of these measures not only protect birds but also offer energy and cost savings for building owners.

Making Glass Visible to Birds

The key to preventing bird-window collisions lies in making glass visible to birds. Here are some effective “Avoidance/Minimization Options” recommended by the Service:

Feather Friendly Window Film
Photo courtesy of Feather Friendly

Glass Options: Several glass and window design features can be integrated into buildings to deter bird collisions. The goal is to create a visual barrier that alerts birds to the presence of glass, prompting them to fly around it. Effective visual cues should cover at least the first two to three stories of a building, or extend to the height of surrounding vegetation. However, even applying treatments to just the first story or known problem windows can still be helpful.

Specific Glass Treatments:

Patterned Films: These films have visible lines, dots, or geometric shapes adhered to the exterior or interior surface of the glass. Birds can easily see these patterns, making the window appear more like a solid barrier.

Ultraviolet Light-Reflective Coatings: Avian vision extends into the ultraviolet (UV) spectrum, invisible to humans. By applying a UV-reflective coating to glass, windows appear reflective to birds, alerting them to the potential danger.

Fritted Glass: This type of glass has tiny ceramic dots embedded within its surface during manufacturing. These dots create a permanent, frit-patterned surface that disrupts reflections and provides a visual barrier for birds.

To check out the entire article from U.S. Fish & Wildlife Service as well as their references, Click HERE.

By implementing these solutions including window film and tint, we can significantly reduce the bird window collisions threat posed by glass to our feathered friends. These measures not only protect birds but can also offer benefits like reduced heat gain and glare in buildings, leading to lower energy consumption and cooling costs.

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