"Hibernate through the winter" - Though it may be printed, it still seems to be tautology, since "hibernate" says it all.About "estivate". The lack of water in very hot summers in arid areas compels amphibians and some reptiles to completely curtain activity and reduce metabolism to a minimum during the dry season. I remember seeing nature program on TV showing frogs buried in quite dry mud coming up very quickly to breed when the rains finally came, and only a short time later having to bury themselves in the mud as it began to dry up again. Fortunate that animals can adapt so well to adverse conditions.