Ranchers in Wyoming told me they stopped rattling because of all the Windmills being put up.... WHich obviously led me to ask why.
He said that the windmills put a lot of vibration into the ground. Snakes feel vibration from us walking. With the windmills up they feel vibrations all the time, so they've quit rattling. Just another theory I guess. Obviously dependant upon windmills being in the area.
-Jake