Last fall, I sat in my dining room and watched as a robin flew full speed into the patio glass doors. Its neck likely broken, it lay lifeless on the patio and quickly died.  There were dozens of robins zooming around at the time, drunk on the orange berries from the nearby mountain ash trees. This was just one ordinary robin, but sadly it’s a common occurrence.

A few weeks later I attended a webinar, hosted by the Audubon Society, that presented efforts to combat the widespread bird mortality caused by window collisions in commercial buildings and residential homes.  We often hear that cats, feral and domestic, kill several billion birds a year in the U.S.  I hadn’t realized that window collisions contribute another billion to this human-caused toll on our dwindling bird population.  Even when birds fly away after the impact, they often die or are more likely to become food for predators if they are stunned or injured.

Birds cannot see plain glass.  They either see through to a distant view of the sky or see a reflection of trees or sky behind them.  Although most bird strikes happen in the summer or during migration, they can occur year-round, at any hour of day or night.

 Affixing silhouettes of hawks or owls to windows is not an effective deterrent.  Research has shown that a better approach is to apply a pattern to the window that enables the birds to see the glass as a barrier. The material should be placed externally and spaced correctly (see below).  Lights visible indoors, especially at night, also create risk.

 Here are a few recommendations from the experts:

• Keep window coverings closed after dark.
• Keep bird feeders close to windows so birds can’t take off from the feeder toward the windows.  Closer than one meter from a window is safer.
• Patterning is important – Vinyl dots can be spaced four inches apart vertically and two inches apart horizontally. 
• Parachute cords or other hanging strips placed vertically four inches apart are another solution.
• Partially closed venetian blinds also form a visible pattern.

Many programs around the country are aimed at curbing window collision bird mortality.  Local birding groups as well as national organizations are working to educate state and local leaders, those in the construction industry and architects about products available to retrofit older buildings or use in new buildings. Many of these programs also target the use of appropriate lighting to minimize the impact on migrating birds, who can become disoriented by light during their night migrations.

Fun fact:  according to the speakers at the webinar, the dirtier your windows are the more easily birds can see them!

For more information:

https://abcbirds.org/glass-collisions/stop-birds-hitting-windows/

https://www.featherfriendly.com/residential
(for removable vinyl dots)

https://www.audubon.org/news/reducing-collisions-glass

Judy Murphy

An excerpt from this article appears in the April 2022 Panorama News.