Buildings & Glass

What is the issue?
Collision with building glass is currently estimated to be the second greatest source of direct mortality of birds.  Bird mortality from window collisions in the U.S. is estimated to be between 365 million to 988 million birds annually.  When we see all the glass and windows around us, and how quickly these are becoming more prevalent in new building designs, it’s no wonder this is such a large source of mortality. 

It’s not just cities that pose a problem; building glass and windows are everywhere.  Birds collide with windows on residential, low-rise, and high rise buildings, or on walkways or bus shelters.  

Why does this happen?
Birds generally do not see clear or reflective glass. Glass reflectivity and transparency create a lethal illusion of clear airspace that birds do not see as a barrier. During the daytime, birds collide with windows because they see reflections of the landscape in the glass (e.g., clouds, sky, vegetation, or the ground); or they see through glass to “habitat” (including potted plants or vegetation inside buildings) or to sky on the other side. The majority of collisions with both residential and urban buildings happen during the day, as birds fly around looking for food. At night, in inclement weather during spring and fall bird migration, birds can be attracted to lighted buildings, resulting in building collisions, entrapment, and exhaustion. While most people consider bird/glass collisions an urban phenomenon with most birds killed at tall, mirrored-glass skyscrapers, the reality is that 56 percent of mortality occurs at low-rise (i.e., one to three story) buildings, 44 percent at urban and rural residences, and less than 1 percent at high rises.

What are some solutions?
Fortunately, awareness of this important bird conservation issue has been increasing quickly in the past few years and is garnering support and action across the country.  Many city and town governments, states, environmental organizations, federal agencies, and members of the public are becoming engaged in finding and implementing solutions.  

This includes development of bird-safe programs and guidance, and working toward increased awareness, education, research, monitoring and even policy development to help reduce bird impacts from buildings.

For the latest information on reducing building glass and lighting impacts, visit the  Bird-safe Glass Foundation website. Please also visit the Migratory Bird Program’s Building, Glass and Lighting webpage, where among other resources you can find the new  Reducing Bird Collisions with Buildings and Building Glass (1.8MB) Best Practices document that offers practical tips for home and building owners and occupants.

In the early 1990s,  Canada’s Fatal Light Awareness Program (FLAP) paved the way for some of the first actions to address and reduce bird impacts from buildings.  FLAP volunteers started by monitoring the streets of Toronto for birds injured or killed when drawn to a building by night lighting and reflective surfaces. 

Since then, FLAP has become one of the leading organizations in helping spread public awareness about the issue and informing policy and developing guidance to encourage bird-safe infrastructure and practices around the globe.   Toronto’s Bird-Friendly Development Guidelines developed by FLAP became mandatory for all new construction in 2010, and many U.S. cities have followed suit with development of similar guidelines and programs, including:  Chicago,  New York,  Minnesota,  Portland, Oregon, and  San Francisco.  The  American Bird Conservancy has also developed its own program and guidelines.

The Service is coordinating several initiatives to reduce bird impacts from buildings, including disseminating information internally and coordinating actions across our programs.  The Service is also coordinating these same actions externally with partners through the Council for the Conservation of Migratory Birds and the Urban Bird Treaty program.

Material on this webpage was sourced from:  Klem and Saenger 2009 (72.8KB),  Loss et al. 2014 (474.1KB),  Manville 2009 (112.7KB)