Places to hibernate can refer to two different types of locations: DENS and LAIRS. DENS are typically small, enclosed spaces that animals use for shelter and protection from the elements. They are usually found in caves, hollow logs, or burrows. LAIRS are larger, more elaborate structures that are often used by predators as a place to rest and hide from their prey. They are usually built with materials such as sticks, stones, and mud, and may have multiple entrances and exits.