Currently you do not have a possible combination to get the standard Birchen variety. That being said if you have a true solid blue hen with no copper in her, you could breed you males to them and get Silver Blue Birchens. Just do not add the copper gene with them.I have 2 Birchen Marans roosters and would like to breed for a few more. I have Black Copper,Blue Copper,Splash,and a couple Blue Marans hens. Will any of these work in matings to the Birchen to produce at least some Birchen chicks?? Thank You....