Art Springsteen sent the following letter
(response sent from mail@cartalk.com).
Dear Sirs,
This is perhaps the one automotive question which I can address with any degree of expertise. I am referring to your caller of January 18 who asked about bird excrement on his automobile and whether birds aim for cars of a particular color. While I cannot comment on the psychological aspect of aeriel bird bombardment, I can speak with some degree of knowledge about bird vision. A colleague of mine, Dr. Melvin Kreithen at the University of Pittsburgh, has done extensive work on the acuity of bird vision, primarily on raptors and pigeons (most likely one of the offending species for your caller). Bird vision is quite unlike human vision. As you well know (from safety colors for school buses and the like), human visual acuity is sharpest in the yellow-green region of the spectrum. For birds, the region is shifted down more to the lower end of the spectrum (lighter green) but also has a very sharp peak in the ultraviolet area (where humans cannot see at all). However, a white car is certainly a more inviting target than a dark green one, which the birds would likely not see at all, especially against a black background of asphalt. As for this gentleman’s comment that the birds seem to hit the car less when his green car cover is on, again, it’s a matter of what the birds see better--they don¹t see light green as well as white.
Dr. Kreithen and I worked together on a project to keep raptors (hawks and eagles) from flying into power poles and power-generating windmills by tailoring the coatings on these objects to match the birds’ visual acuity. It seems to work--the better the birds see an object they are headed toward, the better they are at avoiding it. Now, as for hitting it with bird droppings, well, I guess that’s up to the individual bird.
Best regards from a dedicated listener,
Art Springsteen, Ph.D.
Principal Scientist, Labsphere Inc.
North Sutton, NH
