same here,I have axcually heard the gobble in the middle of the night when an owl would hoot close to him.we sat at the camp one night around the campfire and listen to one gobble (I would say 50 times) and it was between 10:30 and 11:00 pm.

when it full moon and the moon is setting just befor day break, I have heard them gobble over and over for two hrs. till day break.