Last year i was lucky enough to breed some mules for the first time i tried. I used a red mosaic hen, the first clutch was clear but the second 4 eggs all fertile. She hatched and reared all 4 young which turned out to be 2 cocks and 2 hens. They where hatched late, it was the 31st August but they grew well and have made nice birds. I have put the same pair back together this time. The question i have is, will the cock breed or be fertile whilst still showing black on his beak?