ORIGINAL: mez
Good points.
I would caution though that when someone cuts you off from a bird so to speak, don't immediately think that was by intention. If you area good/better than average caller it is very likely that the other guy may think you are a turkey. He may be listening and trying to get between what he thinks is a hen and a tom.
x2
No way to tell without having seen a truck or a person in the area.
My general rule is that if there is a truck parked nearby in a public area.... just go someplace else. I don't like hunting near others anymore than I like others hunting near me. That keeps confrontation to a minimum.