and on the chipmuck color, my blue laced red wyandottes and welsummer both have them and look very different when grown.
most hatchery EE's come in chipmunk, chipmunk x chipmunk will yield chipmunk. I have seen many EE's with various shades color but all have the stripe. It is only when you create your own and use certain colors you lose the chipmunk markings, when other traits are more dominant. I was just at the feed store and looked in the brooder, asked the salesman "what breed" and he said "those are americana". Yes, they were chipmunk striped, as they always are at this place and they get stock from at least 2 different hatcheries. Their "americana" are always chipmunk striped.
I am not saying they aren't silver ameraucana, but it is unlikely. It's just not a common color and even my girls are clean faced, since they were still in the project phase when I got them(I did get one bearded), because of the breed that was used to introduce the color. I never pursued the project just because I didn't hatch any roos, that combined with the clean faces was proving to be a challenge. I decided if I was going to work on any project colors I would develop them myself....that way I know what I am working with, helps you get to where you are going better if you know the genes involved....
