Bill Stevens sent the following letter
(response sent from mail@cartalk.com).
Dear Click and Clack,
Regarding your discussion of auto-albinoguanology (the study of bird doo and white cars):
It is widely known that birds practice guanoflage, the precision placement of poop payloads onto white objects. Apparently this is done to hide these doo-doo tracks from predators. Studies of white street lines, white birch bark and the White House all found significantly more doo-doo per sqare foot on white surfaces than on nonwhite surfaces. (A field study of bird-bombed white cars is sorely needed. Might Car Talk's Research Division want to take on this project?)
Many bird species are accurate bombardiers. I quote from The Birder's Handbook by Ehrlich, Dobkin and Wheye: "There are scattered observations of seabirds that 'divebomb' a pirating foe or a predator at the nesting colony." And some birds, including homing pigeons, navigate partly by odor.
Putting these observations together, it seems likely that birds precisely poop-target white cars in an effort to lay down a navigational odor trail (or just to lighten the load), while at the same time guanoflaging these trails from the prying eyes of predators.
But one thing concerns me: Whenever we move or wash white cars, we may be unwittingly wreaking havoc with bird navigation, pushing them toward extinction. Do you have any proposals to prevent such a disaster? Thanks for initiating discussion of this important matter.
Bill
