Black chickens in your flock give the illusion of crows hanging about. This deters predators such as hawks. Crows naturally alert when hawks are spotted and will mob the hawks and chase them away. We have found this to be successful for our barnyard. We have lost fewer chickens to hawks since we have been breeding the fibro gene into our flock. Not to mention they are stunning birds to see in your mix.
Roosters: Ayam Cemani and Easter Egger.
Hens: Fibro EE, EE, Fibro Maran, Black Copper Maran, Lavender Maran, fibro mix, RIR, Buff Orpington, Lavender Orpington, Wyandotte, White Leghorn, and Turkin