Most likely, if he's crowing, he also has figured out how to breed the hens. Especially if he also has the super shiny feathers on his neck and saddles(back). The wing stomping dance is also a very good sign as someone said.
If you have seen the rooster seem to take an interest in pecking or even grabbing other birds by the head or neck, that's usually the very beginnings of a roo starting to get sexually mature enough to have some fertility.
If the hen is still sitting on eggs, mark the eggs so you know which ones are 'old' or 'fresh'.. and you can use this to test out the rooster's fertility.. if there are no other roosters, you can mark a few eggs (better go with 4 at least, and use the very lightest eggs- whites or very pale tans) and wait a week then candle the eggs. If the rooster is fertile and has bred the hens, you will see the beginnings of an embryo in the eggs.