I ordered 15 Australorp Hens 3 weeks ago and got 16. 3 weeks later, I am doubting their supposed breed and/or gender. I have around 12 of my 16 having brown and black striped feathers on their chest. These feathers are in the same pattern as a Plymouth Rock, but has the white on the Rock substituted with a golden brown. Some of the chickens (such as the one shown) have a golden feather with a black lining on the edge, like a golden laced Wyandotte. I doubt a genetic mutation, because I'm sure that every last one of the chickens I have came from a different mother. These came from Hoover's Hatchery in Dur, Iowa.