Silent But Deadly Bird Predators: Windows

Windows are a major source of human-caused avian mortality. We love windows for the light they bring in and the views they afford us, but for birds, it’s a different story. Each year, between 365 and 988 million birds die in collisions with windows and buildings in the U.S. alone. Birds collide with glass because they don’t see it as a barrier. And at night, artificial light visible through windows increases collision risks as it draws migrating birds near buildings.

While taller commercial buildings have higher per-building mortality rates, deaths from collisions with residential structures kill more birds simply because there are more homes than commercial buildings. Many options exist to limit the toll of windows on birds. Building standards can require the use of products that reduce glass reflection and transparency or limit the number of windows. However, to be effective, such requirements must have buy-in from stakeholders such as architects, commercial building managers, and homeowners.

To gauge how various stakeholders prioritize potential benefits and obstacles to reducing bird-window collisions, researchers surveyed two groups: homeowners and conservation practitioners. In addition to measuring their priorities, researchers also wanted to learn how priorities differed between the groups and how opinions conflicted within each group. To conduct the study, they asked stakeholders to complete a survey that measured the strengths, weaknesses, opportunities, and threats of collision prevention. This is also known as a “SWOT” analysis, and it considers both direct factors and external, secondary factors related to collision management.  

Results showed that overall, both homeowners and conservation practitioners want to reduce bird-window collisions. Both groups ranked the strengths and opportunities of preventing collisions as a higher priority than the weaknesses and external threats related to collision management. Regarding the opportunities, homeowners prioritized recovering bird populations as the most important factor, followed by making bird-friendly building design the standard. However, they also cited obstacles such as the cost of making buildings bird-friendly and a lack of policy guidance. Compared to conservation specialists, there was also more conflict in opinions within the homeowner group, and homeowners were generally more neutral on the issue. 

Like homeowners, conservation practitioners also prioritized bird population recovery as the top factor when it comes to managing bird collisions. They also named fewer collisions and less mortality as birds recover from being stunned as key priorities. However, unlike homeowners, conservationists cited a lack of financial incentives for bird-friendly construction as the key weakness in reducing and preventing window collisions.

Moving forward, animal advocates will play an important role in protecting birds from window collisions.  The authors note that more education efforts should be directed to homeowners about the magnitude of the problem, steps that individuals can take to make their homes more bird-friendly, and the policies in place to address this issue. One source of information is the American Bird Conservancy, which provides helpful resources geared toward the public. The authors also recommend creating formal programs to encourage bird-friendly homes, such as subsidies, grants, and wildlife certification programs.

On the policy front, building codes should incorporate bird-friendly design requirements. The good news is that some U.S. city and state governments already have such policies in place, and there is currently a federal law under review in the U.S. Senate. However, unless the public voices concerns about this issue, builders may not make serious efforts to protect birds in their design and construction. It will take a combination of public education and legislative advocacy to make bird-friendly buildings the norm. Fortunately, we already have the knowledge to fix our built environments. The birds are counting on it.