Why do animals hibernate?

Hibernation is the seasonal process of animals saving energy to survive in extreme weather conditions or food scarcity. To conserve energy, there are specific physiological changes including an animal’s metabolism slowing significantly, slow heartbeats and breathing rates, and a drop in body temperature. Also, during hibernation, body fat or stored food is the animals’ main source of energy. Many misunderstood hibernation as sleeping but it is not, it is a series of bouts of torpor.

Unlike ectothermic organisms whose body temperature depends on the surrounding temperature, endothermic animals regulate their temperature by generating internal heat, which is an energy-required process. Therefore, during freezing weather or food scarcity, endotherms can’t seek food, leading to a lack of energy. As a result, in order to survive, endotherms go into a daily/nightly state called “torpor” to adjust their body temperature and metabolism. In other words, hibernation is a seasonal series of bouts of long torpor.

resource: slate.com

When talking about hibernation, everyone seems to think of black bears. However, surprisingly tiny creatures like birds also hibernate. Actually, for birds, hibernation is one survival way to escape deadly weather and to find an energy source when they are unable to migrate. Not only do animals that live in very cold climates hibernate, but hibernation also occurs in a range of animals living in the arctic to the tropic, in cold to dry seasons as well. Especially in the long dry season when food and water are scarce, many animals start their hibernation.

Hibernation is one way for endothermic animals to survive and conserve their energy due to extreme weather or food scarcity. It carries out some specific physiological changes in order to adjust the body temperature and metabolism. Hibernation not only occurs in cold-climate animals but also in tropical climates and dry seasons.

Resources:

Not just sleep: all about hibernation - Curious (science.org.au)