Birchen Orpington bantams are vary rare with only a small group of breeders specialising in the colour.
The fabulous thing about all three of these colours is that the breeding pens can be changed over to mix the colours depending on what you wanted to breed.
The Birchen colouring has been available in other breeds for many years but is a newish colour in Orpington Bantams.
It is one of my favourite colours and from my original Black Silver Birchen Orpingtons I have created my own line of both Blue and Chocolate Silver Birchen Orpingtons.
DeGaris (1969) WROTE ON BREEDING FOR BIRCHEN COLOUR
Unlike some of the other varieties, such as solid colours, it is not easy to breed to perfection,
Breast lacing will vary from one extreme to the other. It should be fairly fine and stop at the wing butts. If the lacing is wide it is inclined to extend down the body and thighs. If very fine it will stop above the wing butts. Proper lacing and white heads appear to go together, while lack of lacing and dark heads go together. A properly laced bird will hold it for a year or two but as it grows older the lacing will spread. The best mating,of course is one in which lacing is correct in both sexes and all with white caps. On the other hand, offset excessive lacing on one bird with lack of lace on its mate. Birchens continuously exposed to sunshine will finally have brassy hackles and backs. All birds need sunshine but if you plan to show them, you had better limit their exposure to it after the moult.
THE SILVER IN THE CHOCOLATE SILVER BIRCHEN IS A SEX LINKED DOMINANT GENE
In poultry the sex of any chick is determined by the hen not the cockerel. The cockerel carries two Z chromosomes so he is ZZ. The hen carries one Z chromosome and one W chromosome so she is ZW.The cockerel must pass one of his Z chromosomes onto his offspring so any sex linked genes that are on that chromosome such as Silver, Bantam, Barring and Chocolate will be inherited. The hen can pass either her Z or her W chromosome on to her offspring. If she passes her Z chromosome on her chicks will be male and they will inherit all the sex linked genes that are on that Z chromosome but if she passes her W chromosome on, her chicks will be female and they will inherit none of the sex linked genes she is carrying. Genes that are sex linked can only be carried on the male chromosome.
THE CHOCOLATE IN THE CHOCOLATE SILVER BIRCHEN BANTAM ORPINGTON IS A SEX LINKED RECESSIVE GENE
So a cockerel needs two copies of the gene to be chocolate but the hen only needs one.
Chocolate x Chocolate = 100% Chocolate
Black split Chocolate cockeral x Black hen = 25% Black split cockerals/ 25% Black cockerals/ 25% Black hens/ 25% Chocolate hens
Chocolate cockeral x Black hen = 50% Black split cockerals / 50% Chocolate hens
Black cockeral x Chocolate hen = 50% Black split cockerals/ 50% Black hens
Black split Chocolate cockeral x Chocolate hen =25% Black split Chocolate cockerals/ 25% Chocolate cockerals/ 25% Black hens/ 25% Chocolate hens