In my "early years" of turk hunting, I got close to a bird on the roost in Franklin Co, VA. I had a bird gobble ~every 8 seconds (timed), and when he slowed down, I'd throw him a purr or yelp, and crank him up again, double and triple gobblin' - I've never heard so much gobbling from one bird. He'd strut back and forth on the limb, just gobblin' his brains out. After 8am, long after the sun was up, he flew off the limb and down the mountain, and I never heard a squeak from him again - Iwas sure he had worn out his vocal cords. I don't call to birds anymore until they are on the ground...
-fsh