This is what genetic info I copied from another post, with my notes added to try and help figure it out:
Choc is a sex-linked recessive gene that dilutes black pigment. Males with one copy are carriers, but do not appear chocolate. Males with two copies appear chocolate. Females have only one copy of the gene, so they either are chocolate and show it (as all of Hershey boy's daughters should be, if he is indeed chocolate), or are not chocolate and do not show it (as I said before, if Hershey boy is chocolate, then 100% of his female offspring will be chocolate as well - not split and not "not chocolate" since that isn't possible if the dad is indeed chocolate). It wouldn't matter what color the mother is as far as female-offspring of Hershey boy, but for the male-offspring it would matter because they would be split-chocolate if the mother isn't chocolate.
So basically the question here is.....is Hershey boy chocolate or not? If so, all his daughters will be chocolate and his sons will be either split-chocolate without showing chocolate (if the mother isn't chocolate) or full-chocolate (if the mother is chocolate). It would be complicated to find out, if breeding to a dun-female. If you breed him to a solid-black female, it should be much easier to tell if he is chocolate or dun. If it's dun, then some of the male-offspring would also be dun. If chocolate, all of the male offspring would be black (split to chocolate which is recessive), and all of the female-offspring would be chocolate (not split or anything since they only carry 1 copy of the gene, not 2 like the males)
Dun is an autosomal incompletely dominant gene that dilutes black pigment. One copy gives a chocolate coloured bird, two give a khaki coloured bird.
