ABC uses Threat Factors (TFs) to indicate the relative ability of materials to reduce collisions. Products with lower TFs are considered more effective at preventing collisions. A TF of 30 should reduce collisions by at least 50 percent and is ABC's upper threshold for categorizing materials as bird friendly. Learn more about Threat Factors.
Note: No window product, including ABC-tested products, can guarantee elimination of window collisions. Results will vary depending on local bird populations, landscape conditions, product used, and building design. In addition, ratings assume that patterns are applied to the outside surface of glass, or that surface reflections do not obscure the pattern.
Insect screen is an inexpensive and highly effective solution
Insect screens eliminate problem reflections and reduce impact if a bird does hit a window. If possible, use screens that cover the entire glass area of a window.
Stained glass is usually bird-friendly
Stained glass in general is very bird-friendly, as well as serving purposes of devotion or decoration. There is even photovoltaic stained glass! However, if a stained glass panel is insulated, by mounting an external ‘storm window’, it is important to make sure that reflections from that panel of glass don’t cause collisions.
This window film creates a solid appearance from the outside, but allows views from the inside and can reduce glare and cooling costs while protecting birds.
White Collidescape was one of the first bird-friendly solutions available and there is extensive evidence that it stops collisons almost completely - while still allowing a view out the window.
These “Zen Wind Curtains” are easy to install, long lasting and highly effective. The BirdSavers website gives directions to build your own, or order from them from the Acopian BirdSavers website. A lengthy history shows they work extremely well.
1/8" horizontal lines, spaced 0.5", 20% coverage
Tested as IGU, frit, 1/8" horizontal lines spaced 0.5" apart on surface 2, Also on surface 2: low E VE-2M surface . 20% surface coverage