I do like reptiles; I think they're really beautiful, and when, eventually, these two slithered off it looked as though someone had poured them away like water. Adders in England hibernate each winter, and a lot of them may use the same place. They don't lay eggs; they give birth to live young.
There are two very good websites I can recommend:
And I've just discovered that snakes don't hibernate, they brumate... For information on this and diapause, estivation, and torpor, go to