I've heard it called partial albinism, but I think it's leucism in this case--a deficiency in the pigment cells that keep them from producing the proper coloration. I've been told purple finches pick up much of the raspberry coloration from diet, so it makes sense that the pink would be there. But much of the brown pigment across the body is either missing or much muted. Pretty little guy, regardless, though, and I'm still crossing my fingers that he'll show up at the feeders with his buddies this afternoon.
