Vincent Delguercios sent the following letter (response sent from mail@cartalk.com).
Dear Click and Clack,
I caught a portion of your show on January 18. Someone called and related a story about having a white car that is a popular place for birds to leave droppings. It seems he had a similar car that was green and that car did not receive similar bird insults. I would like to present a hypothesis as to how this could happen. As you will see, this is a long-overlooked field of study that deserves some serious research. (Could be the makings of a postgraduate thesis.)
We have a pool in the backyard, and in the spring and early summer birds will quite deliberately fly over and relieve themselves. It is usually mourning doves and robins that particapate in this endeavor. Of course, from above a pool reflects most sunlight that is incident. (Remember that the critical angle for total reflection is around 50 degrees, I think.) So, a bird over a pool or over a white car (which is also quite reflective) would have a similar impulse for action. My proposed reason for birds wanting to defecate into a body of water is that it adds nutrients to the water which would add to plant and insect populations and eventually could add to the birds’ food supply.
Now, taking this line of reasoning one step further, as I am sure you are both quite aware, the human species also has a passion for nautical defecation. Isn't evolution incredible! Gee, I'm glad that cows can't fly.
Vincent
