I was looking to just take a peek at their wing feathers, as they have grown quite a lot of wing feathers and starting to grow in other places Black copper marans chicks are monomorphic, unfortunately, so they’re difficult to sex until a few months old I have seen that an m shaped wing, or 2 steps, indicates.
File:Black colour.jpg - Wikimedia Commons
All chickens can be vent sexed, including marans but this method is costly
Vent sexing is a japanese developed the technique of sexing chicks by looking at the cloacae, the small openings on the underside of birds used for waste, egg laying and mating.
The black copper marans, the most common color variation, are almost all black, with a touch of gold on their necks, and lightly feathered shanks and toes They have a bright red single comb and red to orange eyes. Black black black solid black, or with a few copper spots