I' ve heard them gobble well before any hint of first daylight. One time they were gobbling at a pack of noisy coyotes at 5:10 a.m. and another time I hunted a turkey for several days before getting him and he would be gobbling before 5 a.m. every morning. I' ve got them to gobble with owl hooters or coyote howlers well after dark in the evening also. I' ve never been around any turkeys later in the night to see if they gobble but I' m sure if I were there, I would hear one occasionally, especially when it thunders.