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.
Image drawn on outside of window, using oil-based pen
Painted images can be excellent collision deterrents but must follow guidelines for spacing and other pattern elements to be effective. The pattern shown here meets basic spacing criteria and monitoring at the University has shown it to be successful at reducing collisions.
Recommend installation with 2" x 2" spacing
Intended for application to the inside of windows, non-adhesive, easy to apply, 2x2" spacing recommended. Field tested by Dr. Daniel Klem, on uncoated window glass glass: results may be different on glass with coatings.
These decals, intended to be applied to the inside of the glass, have only been tested on ordinary window glass and may be less effective on windows with reflective coatings. 2x2" spacing is recommended.
Place decals using 2"x2" spacing guidelines
Decals applied to the outside of the glass can be very effective, if applied with 2x2" spacing. Apply to the exterior side of the glass, first cleaning the surface. Many commercial window cleaners leave a residue that can interfere with adherence. We recommend using a 50% water/50% rubbing alcohol solution. Make sure the glass surface is completely dry before installation.
Use non-toxic paint to put up pattern or picture using 2x2" spacing guidelines
Tempera is a quick, inexpensive solution for collisions. It can be applied casually, or with a stencil , to the outside of the glass. You could create different patterns for every holiday. Patterns last a surprisingly long time, even after rain, but can be removed almost instantly.
Use non-toxic paint to put up pattern or picture using 2x2" spacing guidelines
Paint of all types can provide inexpensive, long lasting and highly effective solutions for glass collisions. Plan carefully for acrylic or oil paint, as they may be difficult to remove.
Prescriptive evaluation; reflection test
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.
Prescriptive rating
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.
Prescriptive; reflection test
Stucco, concrete, brick and stone with a matte finish should be safe for birds in any application.
