This is my first experience with chickens, and I'm loving it. I got four chicks, one of which is a speckled Sussex. They're now just over 4 months old, and I've begun to wonder about her (him?). She's always been the most assertive, and now her tail feathers look more like a rooster's, and she has a small nubbin on each leg where spurs would be. The feathers on her back look more like a rooster's feathers, too. She has also been crowing, or something like it. I'm not sure now whether I've got a cockerel or just a really butch pullet. Any help out there?