I don't think we really need to worry much about when they begin or end breeding. We need to be aware of when the hens start sitting on the nest. That is when their behavior changes during the hunting season and we need to change our tactics accordingly.

Gobbling and strutting are used for breeding purposes, but they are also used year round for dominance and peck order. They like the fair weather the same as us, and take advantage of it to do their socialization. That is why you will see them strutting on nice days in February. A good indicator of breeding season approaching is when you start seeing the flocks breaking up.