Alright, running through my pictures of my adult buttons, I realised that the males had started to develop the vent feathers at about three weeks. My current batch is 5 weeks, and I'm not seeing any red vent feathers. I know for sure that the ivory red breast is a hen, simply because this bird is identical to my older gal. I know my luck isn't good enough to have ended up with all females, so, umm, why no red vents? I have cinnamons, two that I'm unsure of, silvers a slate and ivories. I'm not even seeing bibs on them (except for the one ivory), but I remember my original batch developed them later on the males (I think). ETA: Nope, I went through the pics again, and my first two males had bibs starting to show at 4 weeks.