Dear Tom & Ray,
I just heard your latest show (January 18), and it was wonderful! In fact, I'm listening to it again because WRVO (Oswego, NY) rebroadcasts it on Tuesdays at 1:00 p.m. The woman from Alaska, the muffler in the road (with a yellow line painted on it), the 30-year-old woman with 32 cars and the phone call from the space shuttle were very entertaining. It was a great show!
However, I write to discuss the bird/car-color excretory problem that was also a part of that show. I may have an answer--no less correct than any of the automotive solutions you two proffer from time to time.
We are aware that birds do discern colors and can do so far more precisely than can man and many other animals. I remember reading of psychology experiments where pigeons were trained to peck a button for food when a green light came on. The wavelength of the light was approximately 6,000 angstroms. Then, the pigeon was required to discriminate between two lights--one at 6,000 angstroms (for the food) and the other at 5,800 angstroms (for no food). To humans, both lights appeared to be exactly the same green, but the pigeons could discern between them on the FIRST trial (removing position of the lights as a variable). So we know the extraordinary power of birds to discern colors.
Perhaps this ability evolved in order to tell males from females (the males have the brighter plumage)--and those birds who could not properly determine the sex of their mates would obviously have no offspring to pass on their colorblindness. Perhaps the color of nonpoisonous berries holds a greater attraction for birds than that of poisonous berries--and those birds who couldn't tell the difference didn't have the opportunity to pass on their colorblindness gene, either. We don't know the reason, we just know that birds know colors.
But as for passing things other than genes onto the paint of lighter-colored cars, I can only guess (I'm no bird expert--but I do study animal behavior). We know that wolves and dogs, as social animals, tend to use the bathroom where other canines have gone in order to limit the location of their excretory behavior. Dogs don't want dogs to excrete all over the place any more than humans do. That's why we use bathrooms, outhouses and latrines--and dogs use fire hydrants, trees, bushes and telephone poles for liquid excretion and generally contain the solid stuff to certain areas of the yard.
We can infer from this that the same must be true for birds...and since their solid excretion is somewhat white, then it would make sense that, from altitude, white and light-colored cars probably look like a place where other birds have gone before.
As for the gliding and altitude questions that Ray posed: I can only say this from past experience....In 1989, I was entering my mint-condition beige 1981 Toyota Celica (before it was totaled)--the sunroof was open--when I spied, through the windshield, this bird at about 40 feet AGL gliding toward my car and some white material emanating from its fuselage (yes, I once piloted B-52s). I could tell by its release that this "bomb" had a trajectory (course and azimuth) that that would definitely result in my car being hit and that it would probably enter the hole above me known as a sunroof. So, wanting to preserve the quality of the interior of my car--I madly hurried to close the sunroof (a hand-crank mechanism on this vehicle). Just as I closed it, the "bomb" splashed on the top of the middle of the windshield and onto the roof, merely inches away from the now closed sunroof.
Additionally, I too have noticed a greater number of "excretions" on that beige car than on my previous brown Civic and subsequent red and silver vehicles. There must be a genetic cause for this behavior, and if data shows that it is true--I will be reluctant to purchase a white or beige automobile in the future.
Sincerely,
Richard
P.S. As engineers, you already know that: Astronomers measure wavelengths of light in angstroms, a unit of measure equal to one hundred-millionth of a centimeter. It's a convenient shorthand to avoid writing lots of zeroes when talking about the wavelengths of light. In everyday terms, a sheet of paper is approximately 1,000,000 angstroms thick. Visible light covers the range from 4,000 to 8,000 angstroms. (taken from somewhere on the information highway)
