Never known one to rattle until it's shot, or a rock busts it's head. These nature programs that say they rattle as a warning are false in my own experience.
Years ago I hiked many, many miles through the AZ desert and Chaparral. I did run into a few. They rattled, but I was way to close for comfort before they did. Scared the crap out of me.
It seemed in the AZ heat they would hide much of the day.
