What is a Cuckoo Silkie?
A Cuckoo Silkie is a chicken that has barred feathers. The barring on Silkies is not clear like it is on smooth feathers because of the soft, fluffy Plumage.
The darker birds and the males have better markings.
The genetics of Cuckoo (barring):
Barring is incompletely dominant and will almost always show. One copy produces white bars in the bird's feathers and two copies produces wider white stripes.
Barring is sex-linked and can be used to produce auto-sexing chicks. A barred or Cuckoo hen can only pass her Cuckoo gene to her male chicks, but a barred rooster can pass it to both male and female chicks.
A Cuckoo rooster is of much greater importance in breeding. It is only from a cuckoo rooster bred with a cuckoo hen that you will hatch all cuckoo chicks.
Chicks are born without any barring and look like blues.