With 15 chickens you don't need to keep more than one rooster even if the other 14 turn out to be hens (definitely won't happen anyway in a straight run order). The recommended ratio of roosters to hens is 1 rooster for every 10 hens as too many roosters, as they mature, will become very hard physically on your hens; over-breeding them, biting and plucking feathers from their necks and backs, battering them, and potentially, seriously injuring them. It's why whenever I order from a hatchery, I order all pullets, and even then, I always get one or two roosters in the order (most hatcheries only guarantee 90% on pullet orders). The only real reason you need a rooster is to fertilize eggs for hatching and one rooster can easily handle 10 hens in that regard. I currently have 25 hens and no roosters in my flock, and I get loads of eggs without all the aggression, fights, biting and plucking of feathers, feeding of non-productive mouths, crowing in the middle of the night, and over-breeding and battering of hens that goes along with having roosters (especially too many). My hens are stress free, and enjoying life without a rooster.
