Earth Notes: Birds and Glass Collisions

Mar 8, 2017

Here’s a surprising fact: the biggest human-caused threat to birds after habitat loss is window glass. Some estimates suggest up to one billion birds across the United States die each year after flying into glass surfaces. That’s roughly five percent of all birds.

Bird-glass collision
Credit Anguskirk


What’s worse, window strikes kill healthy and rare birds as well as weak and common ones. Victims include many songbirds and hummingbirds whose numbers are already declining. In the Mountain West, fall and spring are especially challenging seasons as birds migrate.

Beyond better building and window design, people can reduce these often fatal collisions by marking or covering glass with tape, string, screens, netting, multiple decals, or one-way film to reduce transparency and reflectivity. Adding awnings and grills can reduce reflections as well.

Relocating bird feeders is also advised—either less than three feet or more than 30 feet away from windows. Simply drawing blinds or curtains helps too, even at night when nocturnal fliers may be lured by household lights. Another option is to move houseplants away from windows so birds aren’t fooled into thinking what’s indoors is outdoors.

Finally, some folks swear by dirty windows. A layer of dust and grime makes the panes more visible to birds. All are fairly simple steps we can take to aid survival of our avian friends in the built world. 

For more information, see the American Bird Conservancy guide on bird-friendly design.