I try to get one close to the roost but my best luck on mature birds is actually walking the tops of the ridges and calling from about 2 hours after sun up to noon when we have to stop hunting. I stay high away from the fields and call every 300 yards or so. Often I hear an answer way down low near the roads and have pretty good luck getting them to come up to my level. I hunt public land and the birds probably learn most of the hunters stay down near the fields. Interestingly enough I have tagged most of my larger gobblers between 10 and 11 am.