I bought cuckoo before I did any research, and I bought them from a hatchery. I thought all marans laid "chocolate eggs". The personalities of my cuckoos and black coppers are very similar, very docile, sweet birds with good roosters, but there is a lot of difference in everything else. I think a lot of cuckoo have been crossed with barred rocks through the years, especially by the hatcheries. I would love to have a full bodied, purebred cuckoo that still maintained the darker egg colorI have both cuckoo and black coppers...for being the same breed they sure do have some major differences.