Spring is a particularly dangerous time for birds, which during migration pass through Evanston in large numbers, risking collisions with windows. 

Between 500 million and 1 billion birds die annually in the United States after flying into windows, according to ornithologists. Window collisions are a leading cause of bird mortality and of population declines for once-common species.

Up to 1 billion birds die annually in the United States after flying into windows. Credit: Laine Hoffman

Evanston is a stopover point for around 280 species – and millions of birds – that migrate through Evanston and Chicago, and stop at our lakefront every spring and fall. Tens of thousands of dead and injured birds have been found over the past 10 years in Evanston, at lakefront buildings, high-rise buildings downtown and at residences.

Here are ways to think through which of your windows might be dangerous to birds and to consider which solution might work best for you.

Which window is a threat to birds?  

Maybe you know a window where birds have hit. If you have heard a bird hit, other birds might have hit as well. Many times raccoons, gulls and other animals remove or eat dead birds so there is no evidence of a bird casualty.

If you do not know which windows are a particular threat, walk outside your house and look at your windows. Pay special attention to the first three floors. Here are some likely trouble spots:

  • Greenery, birdfeeder or birdbath reflected? Look at your windows from the outside to see which windows reflect foliage, trees, birdfeeders or birdbaths. Birds typically land on foliage or feeders and die against windows after takeoff.
  • Fly-through areas. Are there corners, walkways, sunporches or other areas that look as if birds could fly straight through?
  • Greenery inside a window. Are there houseplants are inside your windows? Birds might try to land on it.

Which solution is best for you? 

General requirements:

  • To be effective, solutions – window films, markings – must be applied to the outside of the problem window.  Upper stories may be difficult to reach, unless windows can swing open.
  • Leave no gaps bigger than 4” by 2”. Birds will try to fit between spaces.  This is why decals generally don’t work – birds try to fly between decals and die – unless decals are applied very close.
  • For do-it-yourself methods, windows have to be reachable. For unreachable windows, consider hiring window-washers or a handy-person to do it.
  • Sticking or drawing on windows often requires moderate temperatures, ideally 50 degrees or warmer.
  • No matter what solution, monitor for bird strikes afterwards to see if it is working.

Ceramic pens or nontoxic tempera paint to mark on glass.  Use a straight edge or ruler to make vertical lines 2” apart on the outside of your problem window. Or make up your own design. Opinions differ, but white color ink is preferred by some experts. Pens containing ceramic or tempera paint can be purchased for about $6 to $9 each, or paint crayons are about $2 each from art and office supply stores.

Ceramic pen how-to video: https://www.youtube.com/watch?v=UC9xQkUtQ98

Tempera paint how-to video: https://www.youtube.com/watch?v=jP7K7hdJKYo

Pros: Least expensive, most available solution. Lasts for years. Can be scraped off with a fingernail or other edge, or washed off with water and vinegar. One pen can cover many windows. Easy to add to more windows if needed. Works on any glass: doors, casement windows, sash windows, etc. Can wash windows; just be gentle.

Cons: Requires a straight edge ruler or some skill to make lines look neat. If you make your own design, avoiding gaps 2” by 4” can be challenging.  Washable tempera paint can last years, but in an exposed location with hard rains, parts may wash off.

Window films. You can order dots or various designs and colors. It comes as rolled tape or adhesive sheets, with measuring tape to guide your placement of dots or designs. Cost $2.50 (tape), $8-$12 (dot patterns), and $4-$6 (film), all per square foot.

How-to video: https://www.youtube.com/watch?v=GHZZfUO02xc

Pros: DIY, but looks neater than some DIY. Lasts for years. Can be scraped off. Works on any glass: doors, casement windows, sash windows, etc. Can wash windows; just be gentle.

Cons: Requires measuring your windows in advance and ordering from a vendor. 

External screens, shades or netting: You can install screens, shades or netting on the outside of your window, which will break the reflections, as well as saving birds that still collide with the window. The screen, shade or netting needs to be taut and ideally far enough from the window that birds won’t die if they hit it.

Pros: Possibly a permanent solution. Some products may also provide bug-protection or energy savings.

Cons: Might not be DIY. Requires measuring your windows in advance and ordering from a vendor. Shades, screens, and especially netting, might need ongoing adjustment and maintenance. More difficult to make work on sliding doors or casement windows. Depending on the solution, washing windows might be more challenging.

Hanging chords outside. You can hang chords on the outside of the window. Chords move with the wind, alert birds that a flat surface is there, and are also pleasing to some human passersby. You can affix the strings with Velcro to remove them after migration. Personally, I have found that I end up nailing up the chords with tacks for a permanent solution. 11 cents per square foot.

How-to video: https://www.youtube.com/watch?v=mAH0MKayiEQ

Pros: Long-term solution. Works on sash windows, casements that open vertically, regular doors. No problem with washing windows.

Cons: Requires a little maintenance, e.g., tacking up the chords and sometimes minor untangling. Likely won’t work on horizontal casement windows or sliding doors.

Temporary or emergency solutions: soap or masking tape.  At home one day and hear a thud? Use soap or masking tape until you decide on a permanent solution.

How-to video, soap. https://www.youtube.com/watch?v=LRXqIlLCeYQ

How-to video, tape. https://www.youtube.com/watch?v=dVwC8moggr8

Pros: Short-term solution with often-available materials; can change it later. For tape, no problem to wash windows.

Cons: Not a long-term solution. Masking tape can be difficult to remove if left on too long; if necessary, use hot water to remove. For soap, have to redo after washing windows.

Remember to minimize lighting, too: Lights draw birds to windows, especially in bad weather. Lights also attract insects in unsustainable numbers, leading to over-predation of insects and the decline of bird populations. Turn off lights, whether outdoors or near windows, by 11 p.m., especially during migration. Use light if, when and where you need it, and keep it amber-red and minimized. Use motion sensors or timers, dimmers, and shades. Use phones or flashlights, rather than static lights. Amber is better for birds. (In summer, fireflies blink on the amber spectrum, so they need lights out or on the red spectrum.)

Designing a house? Use bird-friendly designs and materials. More info here: https://abcbirds.org/glass-collisions/architecture-planning/

More Info: American Bird Conservancy https://abcbirds.org/glass-collisions/


Leslie Shad is an organizing member of Bird-Friendly Evanston, and Leads Natural Habitat Evanston, a program of Citizens’ Greener Evanston.

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