Hi, Maurie:

When I lived in the Santa Monica mountains in southern California I had red,
purple, orange, light yellow, and golden rod yellow house finches at my
feeders. I, too, have read that it's the diet but these birds all lived in the same
area and, presumably, at the same foods. Up here in eastern WA I get only red
and kind of a peach color. Perhaps someone "out there" knows of a study done
that could answer the question.

Regards, Joanne
jopowell39 at aol.com
Greenacres (Spokane) WA