I hunt an area very similar. I have only heard a turkey gobble out there once in the past 10 years. That one gobbled twice on the roost and then shut up. Ive killed 6 birds out of there though. Why the lock jaw? I dont really know. Hunting pressure isnt bad at all. These gobblers arnt always with hens either. There are alot of predators in the area though. Domestic dogs running through there frequently as well as coyotes. Bob cats are also very numerous. This may have something to do with it.