Hares belong to the family Leporidae within the order Lagomorpha, a group of mammals that includes rabbits and pikas. The simple answer to whether hares hibernate is no; they do not enter a long period of winter dormancy. Their entire survival strategy is based on remaining active and foraging throughout the year.
Defining True Hibernation
True hibernation is a complex physiological state of sustained, deep torpor where an animal’s bodily functions are drastically suppressed for weeks or months. This highly regulated process is typically triggered by changes in day length and hormone levels, allowing the animal to survive extreme cold and food scarcity. A true hibernator experiences a profound drop in body temperature, sometimes falling close to the ambient temperature of its den.
During this deep sleep, the animal’s metabolic rate can decrease to as little as 5% of its normal rate, and its heart rate can slow from hundreds of beats per minute to just a handful. This metabolic suppression allows the animal to survive exclusively on stored body fat for long periods. Hares lack the biological mechanisms to enter this sustained, low-energy state, as they maintain a relatively high body temperature and must feed daily.
Active Winter Survival Strategies
Since hares cannot rely on torpor, their winter survival hinges on a constant, active search for food and shelter. They are obligate foragers, meaning they must feed every day to meet their high metabolic demands. This daily necessity forces them to navigate the winter landscape continuously.
Their diet shifts dramatically from tender grasses and herbs to tougher, more fibrous woody vegetation when snow covers the ground. Hares subsist on the bark, buds, and small twigs of various shrubs and trees, often stripping the lower ring of bark from saplings.
For shelter, hares do not dig burrows like rabbits; instead, they rely on shallow depressions in the ground called “forms.” These forms are typically situated in dense cover or under low-hanging branches, providing minimal protection from wind and predators. Arctic hares may dig shallow scrapes or short tunnels into snowdrifts for better insulation against the intense cold.
Physical Adaptations to Cold Environments
Hares possess anatomical and physiological traits that allow them to sustain activity in freezing temperatures. One visible adaptation is their thick, dense pelage, which provides superior insulation against heat loss. In many northern species, the coat undergoes a seasonal color change, transforming from brown to pure white for camouflage against the snow, a mechanism known as seasonal molting.
Arctic hares exhibit a stockier build, with proportionally shorter ears and limbs compared to warmer-climate relatives, reducing their surface area-to-volume ratio. This compact body shape minimizes heat loss, allowing them to maintain a stable core body temperature near 38.9 degrees Celsius. Their large hind feet are heavily padded with fur, acting like natural snowshoes that distribute weight over the snow’s surface and insulate their paws.
Hares often carry a modest amount of fat, around 20% of their body mass, utilized for energy during sustained movement and to fuel their high metabolism. Some hares, like the Arctic hare, possess a basal metabolic rate that is naturally lower than predicted for a mammal of their size, which is an energy-saving adaptation that supports their survival in cold, food-scarce habitats. They also employ behavioral strategies, such as tucking their extremities in tightly when resting, to conserve body heat.