For the Birds: Window strikes are deadly

Sparrow windowkill.  Photo by Scott Carpenter.

By Christine Southwick

Window strikes kill approximately 100 million birds a year.

There are two types of window strikes: unintentional; and territorial defense.

The first type is caused by an inability to detect clear glass, and is usually fatal due to the speed of the bird. Birds rely on visual clues; glass creates a barrier to a visual path.

The second type is territory-defending-males during breeding season, and though not fatal, can make a home dweller think deadly thoughts. Robins are the most notorious, often going from window to window, for days on end trying to run off that reflected aggressive male. I once saw a Nene goose in Kauai attacking a reflecting car bumper for half a day.

Cooper's Hawk. Photo by Janet Millard.

Migrating flocks die flying into lighted buildings at night; night being the safest time for songbirds to travel. The rest of the birds die from window strikes either at resting stops or their nesting spots.

This is where we come in. We can move feeders either 25 feet or more from windows, or within three feet. Distant feeders allow more paths of disbursal. Close feeders don’t give birds time to gain enough speed to hurt themselves on impact. Even better, we can break up reflections in our windows.

Reflections from windows can appear to be open space, or a rival male. The best way to break up reflections is to put something on the outside of windows. Putting screening or shade cloth over the whole window is the fastest and surest solution. There is a new film called Collide Escape that is easily applied directly to the outside of your window. Birds see a white area, but people inside can see right through it. 

Varied Thrush. Flew into window
escaping a predator. 
Photo by Amy Schillinger

Another option is to put up moving stringers that include feathers. They can be placed in front of windows like an art display.

Silhouettes don’t work unless there are several all over each window.

Juvenile and adult birds die from window strikes. Remember the downtown female peregrine who preceded Bell? She died when she flew into a corner window while chasing her dinner-to-be pigeon.

It is estimated that 50% of all window strikes are fatal—on impact, or after, due to internal injuries or slowed reflexes. The majority of bird bodies aren’t seen because opportunistic predators are looking for tasty meals.

Save birds. Put up screens and eliminate the reflections. You’ll be glad you did.