Brumation

Brumation is the state that cold-blooded animals utilize during very cold weather. Unlike mammals who are in a deep sleep throughout the dormancy phase, reptiles do not enter this state when they are brumating. Instead, their dormant phase is typically characterized by long periods of inactivity with bouts of activity in between. They crawl out of their burrows whenever it is warm outside. They may not eat anything when they come out, but they do have to drink water to avoid dehydration. On the other hand, hibernating mammals neither eat, nor drink anything during this phase. 

Migration

Some dragons migrate, spending the summer months grazing in the tundra before cooling fall temperatures send them south into the taiga for the winter. The taiga is a forest of the cold, subarctic region just south of the Arctic Circle.

Many animals such as moose, bear and lynx live in the taiga. This is an important food source for migrating dragons. The soil beneath the taiga often contains permafrost which can provide material for creating nests for hatchlings.

Hibernation

Dragons may enter a state of inactivity that animals resort to in order to avoid damage from low temperatures - so think of it as winter sleep. Before living things go into hibernation, these animals eat a lot of food and store it in their body in the form of fat. Once they gain sufficient weight, they take shelter in a warm place where they will spend the rest of the winter in deep sleep. During this period, they reduce their heart rate by as much as 90%. There is no specific period of hibernation, and it can go on for weeks and even months.

Hibernation is further divided into two types: true hibernation and false hibernation. When we speak of animals going into deep sleep where they are not affected by sound or touch, it refers to true hibernation. As opposed to this, in false hibernation, the animal involved can easily wake up from its sleep.