I've read that as a buck matures, he doesn't need to always be feeding as much, therefore can layup much more during the daylight hours, making it seem like he is getting mroe nocturnal. Depends on whether I should believe that or not, I forget where I read/heard it.

Now from a pressure standpoint I thinkbucks learn REAL quickto only move after dark or be dead.

My own personal beliefs based on reading and observing are that a mature buck going nocturnal is 20% of his own doing and 80% of his surroundings(pressure).