>I thought all this was interesting because I have always assumed, without
>giving it much thought, that Rock Doves were so variable in color because
>people have a tendency to notice the odd-colored bird in a flock and are
>more likely to toss the food in that direction.

I think the odd coloration comes from domestic pigeon-breeders originally. The
question probably is why do oddly colored pigeons continue to breed and not
get weeded out.

Domestic pigeon-breeding actually does raise some interesting genetic issues.
Steven J. Gould wrote one of his essays some years back about a scientist in
England that studied domestic pigeons. One of the patterns that develops on
pigeons is a dark-checked pattern on the wings and mantle, as opposed to
the two-striped "wild" kind. Apparently, if you have a population of the
dark-checked kind, you can breed the pattern out until you get the
two-striped. But once you've gotten rid of it, you can't get it back - the
two-striped can't be bred to have a dark-checked pattern. No amount of
selective pressure, artificial or natural, can create a trait if the
underlying genetics aren't there, (unless you sit around an wait for a
mutation.)

John Chapman

Seattle