http://bcnbirds.org/window_files/WindowCollisionFactSheet.pdf
Information compiled by Bird Conservation Network October 2002-02,
Randi Doeker www.iit.edu/~cos/BCN
Reformatted by Paul Hunter and posted as
http://home.wi.rr.com/phunter1/birdwindowcollision.html ...
2/21/04
WINDOW
GLASS: THE DEADLIEST HAZARD FOR BIRDS
Birds do not see glass .
- Scientific research has documented that birds do not recognize
that glass is a barrier to be avoided. Birds don't see windows and,
thus, fly head-on into them, often at very high speeds. It is the
number one human-related cause of bird mortality.
- Birds strike every size of window, in all types of structures, in
every season, day and night. Window strikes are equally lethal for
large and small species.
- Fifty percent of birds that hit windows are killed. Expert
estimates of the number of birds killed each year by window strikes in
North America start at 100+ million.
- Window collisions have been documented as a serious threat to the
reintroduction of species (like the Peregrine Falcon) into urban areas.
Why do birds collide with windows?
• Windows reflect nearby trees causing
birds to think the trees continue
• Windows reflect the birds flying toward it, causing them to think it
is a flight pathway
• Bright lights near the window, outside or inside, attract the birds
• Windows are transparent; the birds don't see it
• Windows are transparent and something inside, like a plant, attracts
the birds
• Windows on two sides of a room appear to provide a clear passage
through
• Birds see their own reflection and believe it is a competitor to be
driven away
• Feeders are near windows -- the bird hits the window when trying to
escape a predator
What does not work
• A few scattered decals; the entire
window must be covered
• Owl forms on the roof of the building.
What you can do
Reflective Windows: Put something on
the outside of the window to alter the appearance of the entire window.
The coverage must be total and allow for openings no larger than 4
inches (10 cm) across.
Options:
1) Hang strips of 1+ inch wide paper /
ribbons / string / mobiles every four inches
2) "Frost" or "etch" the glass using techniques popularized by
decorating books and websites
3) Sponge or stamp on a decorative pattern with soap or thinned window
paint
4) Cover the windows with "CollidEscape" perforated film to make
windows visible to birds while allowing those inside clear view to the
outside
5) Cover the window with decorative films
6) Cover the window with a fine-mesh net so that the birds bounce off
7) Apply any form of non-reflective, contrasting decals that uniformly
cover the entire window
٠ Spider webs are believed to be the
most effective
٠ Hawk or Owl forms are no more or less effective than other shapes
8) Install outdoor blinds
9) Install hanging objects that cover the entire window area when moving
10) Move bird feeders, baths and other attractions (like nutritious
vegetation) against the window or more than 10 feet away.
Transparent windows - Additional options
Close curtains / blinds
Move houseplants away from windows
At night, use only low-intensity lighting
Use task lighting with lamp shades that direct the light away from
the window
Dim overnight lights (especially in atriums) to lowest level or
extinguish
Reference Sources
1. Animal Protection Institute
(www.api4animals.org)
2. Fatal Light Awareness Program, Toronto (FLAP.org)
3. Havahart.com
4. Journal of Field Ornithology
5. Professor Daniel Klem, Muhlenberg College - various presentations
6. National Audubon Society (www.audubon.org)
Product Sources
٠ Decorative etching techniques:
www.hgtv.com -- Search on "frost glass"
٠ CollidEscape film - check www.flap.org for details
٠ Simulated etched glass film: www.spandex.nl -- Search on "etched f
ilm" for a variety of choices
٠ The Warning Web - spider web decal from Lee Valley & Veritas
Tools (www.leevalley.com)
٠ Whispering Windows Anti-Collision Window Decals - www.wpines.com
http://www.birdmonitors.net/reducerisk.html
from Chicago Bird Collision Monitors
http://www.flap.org/new/prefr.htm
from Fatal Light Awareness Program in Toronto
http://bcnbirds.org/window.html
from Bird Conservation Network of Chicago
https://www.abcbirds.org/birdconservationalliance/members/window_paper.PDF
from American Bird Conservancy
http://www.fws.gov/birds/documents/Glass.pdf
from International Migratory Bird Day
http://www.fws.gov/birds/documents/Collisions.pdf from
International Migratory Bird Day