Lizards hibernate during the cold periods of the year, making their homes in tree trunks, rocks and wherever they can find shelter. Lizards are cold-blooded ecnotherms with no internal heating capabilities, so they must rely on heat from external sources. When winter comes, they are forced into hibernation.
Lizards generally hibernate alone, but some species have been observed in group hibernation. The need for food is diminished or even eliminated in some species during the hibernation period.
Some lizards go into estivation instead of hibernation. Estivation occurs among lizards living in dry, hot areas of the world, such as arid deserts, and it involves lizards burrowing themselves away to escape the extreme temperatures.