Gobbling in the spring is an indication the mating season is getting started along with a lot of other signs. Other signs can be found by watching them in fields in the pre season and observing behavior and who's together, scouting, etc. You are correct in one aspect, gobbling is not limited to just the spring mating season....i too hear birds in the woods when i deer hunt on occassion, but it's because something shock gobbles them and it's an entirely different deal. It's knowing and understanding the difference in a shock gobble and a mating gobble compared to when it occurs in the fall and when it happens in the spring. If anyone in SC is hearing gobbles and seeing signs I'd love to here from you.