Birds and the Danger of Window Collisions

Image of Sarantia Katsaras

Bird Conservation Program Technician Sarantia Katsaras

Windows are one of the leading human causes of death for birds.

Windows are not always visible to birds due to reflected trees or skies, a view straight through the window, or potted plants or living walls on the other side of the glass that draw them in. In order for a window to become visible to birds, it needs to be “broken up.” Visual markers such as patterned window films, window curtains, or window screens make windows visible to birds. By adding these features, it breaks the window up and lets the bird know that it cannot pass through.

This photo is of 1,800 birds that fatally collided with windows in Ottawa this past year.

This photo is of 1,800 birds that fatally collided with windows in Ottawa this past year. Demonstration put on by Safe Wings Ottawa/

As many as one billion birds fatally collide with windows in North America annually. According to Safe Wings Ottawa, as many as 250,000 birds are killed by windows every year in Ottawa and Gatineau alone. Most window collisions occur during the fall and spring when the birds are migrating. In 2016 there were 101 different species of birds recorded in Ottawa. This includes species at risk such as the Peregrine Falcon, Chimney Swift, Eastern Whip-poor-will, Eastern Wood-Pewee, Wood Thrush, Rusty Blackbird, and Canada Warbler.

FLAP Canada estimates that 1 to 10 birds die per building, per year.

For reasons currently unknown, the Canada Warbler is highly vulnerable to window collisions compared to the average species. Canada Warblers are at 17.9 times greater risk of colliding with all building types, 25.8 times greater risk of colliding with high-rise buildings, and 46.7 times greater risk of colliding with low-rise buildings. The Canada Warbler is a threatened species and its population cannot withstand this easily preventable threat. Interestingly, birds are more susceptible to low-rise buildings than high-rise buildings. Birds typically collide with windows between 50 to 60 feet tall.

Make your windows at home visible to birds by taking these steps

To learn more about this issue and this significant threat to birds visit our Save Bird Lives page.

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