Greg:

I haven't seen any replies on tweeters to your request for comments on the
problem of window kills, so I'll give it a try. We had considerable
mortality at a glassed-in walkway that connected two of our buildings in
the WSU campus back in the 1960's and 70's, so George Hudson (my
predecessor in Conner Museum) placed raptor silhouettes on the windows. We
kept data on the kills before (1968-June 70) and after (July 70-74) the
placing of the silhouettes and found that it reduced mortality to about 1/3
of the former level (see: R.E. Johnson and G.E. Hudson, 1976, Bird
mortality at a glassed-in walkway in Washington state. Western Birds
7:99-107.) We couldn't be sure if raptor shapes were what was important,
or simply the fact the "something" was on the windows to alert the birds to
the glass. Of course mortality will differ according to the situation. In
our case the birds could see straight through the walkway, which was
narrow, and the birds probably didn't perceive there was an obstruction
unless the silhouettes were there. (For a picture of our walkway, see:
L.Palmer, 1976, Through a glass darkly. Pacific Search 10(6):10.)

In other cases birds probably instead see reflections of themselves, or
worse, of the habitat in front of the glass. This can be especially bad if
the glass is intentionally created to be reflective, as on some modern
buildings. This problem was discussed by Richard Banks in an article in
BioScience (1976, BioScience 26(6):414).

Most of the mortality both we and Banks saw occurred during fall and spring
migration, which suggests that some additional short-term, though perhaps
less aesthetic, remedies during these periods might be especially
justified. Placing screens over the windows during those months comes to
mind. Presumably the birds would notice the screen and slow or veer off.
And if they didn't, the screens would soften the contact to the point
where, hopefully, no lasting damage to the bird would occur.

Some other articles that might be of interest:

Klem, D.,Jr. 1989. Bird-window collisions. Wilson Bulletin 101 (4):606-620.

Klem, D.,Jr. 1989. Bird injuried, cause of death, and recuperation from
collisions with windows. J. Field Ornithology 61(1):115-119.

Klem, D.,Jr. 1990. Collisions between birds and windows: mortality and
prevention. J. Field Ornithology 61(1):120-128.

Klem felt that raptor silhouettes were not very effective, but he makes
several other suggestions.


Richard (Dick) E. Johnson
Conner Museum, and School of
Biological Sciences
Washington State University
Pullman, WA 99164-4236
johnsonre at wsu.edu




>Hi Tweeters and Chatters,
>At several of our outdoor exhibits visitors view the displays through
>large plate glass windows. During migration we have had birds killed
>after flying into the glass, and have adhered raptor silhouettes to deter
>such incidences. We still have occasional casualties. Can anyone comment
>on their experience with the effectiveness of this device, or suggest ways
>to improve its use?
>
>
>Greg
>
>Greg Toffic
>Curator of Birds
>Woodland Park Zoo
>5500 Phinney Avenue N.
>Seattle, WA 98103
>(206)684-4836 PH
>(206)233-7278 FAX
>greg.toffic at zoo.org
>
>"Metaphors be with you"