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Wednesday's Wildlife: Window Strikes

You are at home when you hear something hit the window. You go outside to investigate and notice a small bird standing between a planter and your window.  Its feathers are fluffed, its eyes are closed, and it doesn’t seem to notice you are there. Did the bird fly into the window and if so, how can you help?

Yellow Warbler in flight
Figure 1: Yellow Warbler in flight.


Window strikes occur when bird or bat flies into a window. While birds are known to be mostly affected by window strikes, it can also happen to bats.


Bats echolocation gets confused when used on smooth surfaces, like windows.  This is one explanation for why bats end up striking windows.


Nighttime window strikes are often due to light pollution and reflective structures, on the flightpath of migratory species, which can be disorienting. Daytime window strikes are often associated with birds flying through what they perceive as a habitat corridor between trees or open sky but is in fact a reflective surface like a window.

Windows reflecting vegetation.
Figure 2: Windows reflecting vegetation.


Bird fatalities are linked to how fast a bird is flying and how near vegetation (trees or shrubs) is to reflective surfaces.  Vegetation within a three to thirty foot distance are more likely to result in fatal bird injuries as they can fly at fatal speeds into windows attempting to fly to the vegetation that is reflecting into the surface of the window. 


Birds that strike windows can end up with many different injuries, the most common being a concussion. Signs that a bird has a head injury include walking in circles or being still and fluffed up as previously described.  Broken wing bones are another injury that can be sustained.  Fortunately, if the bird is quickly taken to a wildlife rehabilitation center, they can receive the care required to recover from these injuries and released.


It's important that after a window strike, a bird or animal is brought in for assessment.  Concussions can make it difficult for wildlife to thermoregulate, or cause less obvious injuries such as internal bleeding or other body system failures.  A wildlife care professional can assess their injuries and give care when it is needed.


How can you help prevent window strikes?

Window art examples to help prevent bird window strikes.
Figure 3: Decals or art on the outside of windows about two inches apart can help break up the reflective surface of a window and prevent and reduce window strikes.


Add decals or hand drawn art to the outside of windows, separated by about two inches.   

Feather Friendly window treatments can also prevent window strikes. Feather Friendly can be purchased on the Calgary Wildlife online store.

Read Feather Friendly case studies here:


Turning off lights at night and keeping large plants away from windows are also ways you can prevent window surfaces from being an inviting flyway to birds!


Uncertain whether wildlife needs help? Found injured or orphaned wildlife?

Please call Calgary Wildlife at 403-214-1312.






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