from what I have read, chocolate can be sexlinked and choc can be ?? something else. in the UK, they have a different kind then we have with the dun gene.
I also saw an interesting picture in grant brereton's genetics book that showed a bird that was being called chocolate but was actually a deep red geneticly (according to him). I could see how it could be called chocolate so you have to be careful and know the backround on the birds.
this might be where the chocolate from the blue and buff birds appears, maybe it's not really chocolate but like this deep red bird.
I also saw an interesting picture in grant brereton's genetics book that showed a bird that was being called chocolate but was actually a deep red geneticly (according to him). I could see how it could be called chocolate so you have to be careful and know the backround on the birds.
this might be where the chocolate from the blue and buff birds appears, maybe it's not really chocolate but like this deep red bird.