If you have a black chicken and can't tell what breed it is (like me) here's what the state poultry vet told me. I guess this only works for telling the difference between Black Jersey Giants and Black Australorps, but here goes: Catch the chicken. Wash the mud, poop, and other random stuff of the BOTTOM of a foot. If the BOTTOM (as in the part that's always touching the ground) is: White = Black Australorp Yellow = Jersey Giant Hope this helps identify some of those chickens out there! I didn't know what mine were till I called him and he wanted to know what breeds I had. I have Australorps, BTW....LOL!!