New Report Shows a 94% Decrease in Avian Window Collisions at City Building after Retrofit

A new report from Bird Alliance of Oregon in concert with the City of Portland Bureau of Environmental Services shows that application of a striped bird-safe film to window glass at the City owned Columbia Building in North Portland resulted in a 94% decrease in bird window collisions. The report points to the effectiveness of adding window treatments to existing commercial and residential buildings in reducing collision-related deaths. 

A view of the glassy exterior of

Window collisions are considered by scientists to be among the top three killers of birds in North America, along with habitat destruction and outside-roaming pet and feral cats. Most collisions occur within the first three floors of a building. 

“A 2019 Cornell University report indicates a staggering 30% loss of our North American bird populations since 1970, which is a call to action for us to double down on measures to reduce mortality factors for birds,” said Mary Coolidge, Bird Safe Campaign Manager for Bird Alliance of Oregon. “We applaud the City for addressing the issue and taking corrective measures to resolve the significant hazard that this building posed.”

The joint report studied an avian collisions mitigation project and the associated pre- and post-retrofit monitoring at the Columbia Boulevard Wastewater Treatment Plant’s administrative Columbia Building in North Portland. The building opened in 2014 and features floor-to-ceiling windows on its north side. Building occupants immediately noticed birds colliding with windows, and subsequent monitoring showed a minimum estimate of 125 collisions per year resulting in an estimate of up to 96 avian mortalities per year.

The building was retrofitted in October 2017 with Solyx full-coverage horizontal line patterned window film applied to the exterior of the windows. Post-retrofit monitoring yielded a 94% reduction in the strike rate at this building with a post-retrofit estimate of 7.5 collisions per year. 

A close up of the Solyx full-coverage horizontal line patterned window film on the window.

 “Just like people, birds will run into glass if there are no visual clues that it’s there, but effective solutions do exist.” said Dave Helzer, Terrestrial Biologist for the Bureau of Environmental Services. “We’re thrilled that, with support from experts at Bird Alliance of Oregon, we were able to find a solution that helps protect declining bird populations.”

This is proving to be an incredibly challenging migration season for birds—between forest fires, droughts and cold fronts—all of which are likely contributing to astonishing mortality rates of birds. Trends toward glassier buildings have increased the collision hazard in the built landscape. Luckily there are solutions that can be incorporated into the glass or the building façade design, or that can be applied as a retrofit later. Bird safe measures have recently been taken at the Oregon Zoo’s Education Center and at the City’s Hannah Mason Pump Station in Willamette Park, both using etched glass in the original design, as well as window film applications at the Tualatin River National Wildlife Refuge Visitor’s Center in Sherwood and at the new Providence Park expansion in Goose Hollow. 

In recent years, the City of Portland has adopted a number of programs and policies to protect birds from window collisions. This includes the joint development of a Resource Guide for Bird-friendly Building Design with Bird Alliance of Oregon in 2012, integrating bird safe building considerations into the City’s Green Building Policy in 2015, and adopting bird safe building requirements for the Central City in 2018.  The City has recently developed a Dark Skies Report and Recommendations document, which includes a proposed timeline for implementing measures to reduce nighttime light pollution, which is a major factor in contributing to avian window collisions. 

“Portland has demonstrated strong leadership in enacting measures to reduce avian window collisions,” said Mary Coolidge. “The work done by Environmental Services demonstrates just how effective those measures can be. It is critical that we continue to build upon existing policies to ensure that Portland remains on the cutting edge of protecting wild birds that live in and migrate through our city.”

Most window collisions happen at low-rise commercial buildings and 1-3 story homes. There are a range of ways to help reduce window collisions at home from DIY to more sophisticated solutions, including:

  • Moving bird feeders to within 3 feet or more than 30 feet away from windows;
  • Installing standard insect screens; 
  • Illustrating on windows with paint pens; 
  • Or having an exterior film installed by a professional. 

Bird Alliance of Oregon’s website includes Tips for Reducing Window Strikes at Home. A video entitled How You Can Reduce Hazards for Birds at Home is also available on Bird Alliance of Oregon’s Facebook page.

Click to learn more about avian window collisions and what can be done to prevent them.

View the full report here.