the white wing feathers and a cuckoo like chest are impurity in the black coppers strain all around a world .they go a way when they grow, but there s a pure clean black coppers strain no white feathers what ever. .
in my experience from last year we hatched 500 black coppers chicks from all the lines ( strain ) in the country we got 40 chicks pure black ER/ER not one white feather on them.We kept them all and selected from them.this year we are in the second generation F2. from this F2 only 30% of they chicks have a white feathers the other 70% are pure Black, the way they should be.
even in France I have seen a lot lines with a white feathers when young .
we need to breed and select very carefully one generation at the time. I found the black chicks are better than a penguin type ones.
Next year 2016 we are going to start ours lines.2 pullets lines and 5 cockerels lines .
Did you test mate?
See haze on the chicks chests- are the hens overmelanized? Can we please see some photos of the parents?