"Dark" in Brahmas is the same variety as silver pencilled. This is an extremely sexually dimorphic variety with females being pencilled and males being black chested with silver saddle and hackle feathers. With the first set of wing feathers, both genders will often have pencilled wings so ignore the wings. Cockerels on their chests and bodies will be a splotchy mix of black and white. Your chicks' chests and white shoulders are dead giveaways. Here is a pullet Silver Pencilled Rock for comparison. Note how the chest is clearly pencilled and there are no white shoulders emerging!Thank you! We figured they may be and that's why they were dumped. Can you educate me on how you know they're cockerels?