I have never rattled in December but the largest and most agressive Mule Deer fight I have witnessed happened in December. Two large bucks started to fight over a doe and all of a sudden all kinds of bucks started to come from different pockets of Brush/Trees. The mid-size bucks just watched and then all of a sudden they went at it with each other. this wasn't the typical sparring match, it was a brawl. Never seen anything like it and never seen anything like it again.