I spent lots of time and money trying to get my Black Copper Marans to SOP, but everyone of the males ended up with white tail feathers. I finally gave up and started a dark egg project with them. I'm in the first phase and can hardly wait on the chicks to grow and start laying..
Ya...Birchen based birds are not easy to breed. The Black Copper Marans seems to be a variety that gives lots of people head aches.
You will have to give me up-dates on the Dark Egg project. I would love to see what you learn about the egg color. About everything I know about the dark egg color is from personal observation. Others of couse offer their theory on breeding for dark eggs, but few if any trap nest so they don't know where their color is coming from and what I have been observing doesn't really follow with the conventions most people are offering.