They've got fall/winter feeding grounds and they've got the spring brood grounds. They're going to move to where the hens have everything they need for nest cover, water, etc. If the winter grounds are good enough to cover those needs, it's quite possible they'll hang around. If not, they're moving on. Also, gobblers will move to an area they can strut and be seen from a greater distance. It helps with eye appeal. There's a reason we see them in the fields more often in spring than in other times of the year.