[adamanteus]

Gertie, the reason Garters use communal hibernation dens is because of the small numbers of suitable sites, this is not a social act and is quite well documented. These dens are often used by different species.

For example, Black Rat Snakes are sometimes referred to as Pilot Snakes or Rattlesnake Pilots because of the erroneous belief that they guide Rattlesnakes to winter dens. Dens in which Rattlers and Rat Snakes over-winter together. Mass hibernation is simply a matter of need... there are very few dens for very many snakes. Of course snakes have no means of 'passing the word' to hundreds of other snakes scattered across a wide area.