I've heard of feather sexing, but I don't know if it works on all breeds or not. When I picked out my birds at our feed store, I tried to get ones that were a week or more old. I chose from the groups of sexed pullets (supposed to be 90% pullets at least), and I picked out the ones that didn't appear to have any boyish traits hoping to increase my odds. If one had a larger comb, thicker legs, a small tail, or wasn't growing feathers across the wing bows as well compared to the rest of the group, I didn't pick that one. So far it has worked for me, my six birds are all girls.