Snakes are ectothermic animals, meaning that their body temperature fluctuates with that of the environment. This means that the snake’s body temperature will be high when it is hot outside and vice versa.
Snakes cannot handle cold temperatures so they enter a state of prolonged inactivity similar to hibernation, known as brumation.
Most snakes brumate between September and late April when the climate is really cold. During brumation (snake hibernation), some snake species may wake up time and again to quench their thirst, which is an activity that occurs during brumation but not hibernation.
List of Snakes that Hibernate
1. Black Rat Snake
These are non-venomous snakes with a variety of prey that they kill by constriction since they are large and powerful. They are mostly found in the United States and lounge near henhouses since they eat chicken eggs.
During hibernation, black rat snakes hurdle with other species of snakes such as bull snakes, racers, and rattlesnakes. After hibernation, these snakes emerge from rocky crevices in early May. They prefer to hide in deep woods and overgrown fields.
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2. Blue Racer
Blue racers can be found hibernating under frost lines in rock crevices and old foundation burrows, where they hibernate communally alongside other species of snakes. They hibernate during the months of September through November, although the hibernation period may end in late March at times.
The hibernation period involves the snakes moving in large groups towards their hibernation sites to evade the cold winter months. Blue racers are found in savannas, meadows, weedy lake edges, and hedgerows. Such habitats make it easier for them to fulfill their ecological and biological needs.
3. Caspian Whipsnake
When the cold season approaches, the snake looks for a favorable location with good altitude and climate to hibernate for four to six months. The Caspian Whipsnake is the largest snake species in Europe. It is diurnal and non-venomous.
Whip snakes burrow deep inside man-made burrows that allow the snakes to hibernate even deeper. Sometimes the snakes fail to come out of hibernation if the temperatures become too cold while they are buried deep below the surface.
Caspian snakes hibernate with other snakes and reptiles in groups, which means they have reduced activity but remain responsive to their environment. Changes in weather or climate, such as flooding, are the most common cause of death among these snakes during hibernation. Whip snakes die of starvation during the harshest winters, but in cases of forest fires, they can vacate their hibernation regions and look for new camping grounds.
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These snakes are most commonly found in North America, and they are highly likely to bite, but they have relatively mild venom that is not fatal. Like rattlesnakes, they are pit vipers, and their bodies have a dorsal pattern of dark and chestnut cross bands. Copperheads are found in southern New England, West Texas, and Northern Mexico.
They are semi-social, and they prefer to hibernate in communal grounds, which they return to every winter season. Copperheads hibernate in rock fissures, stump holes, and other sheltered places below the frost line. Hibernation sites can be shared with other snakes of different species, and they emerge later compared to other snakes.
5. Dice Snakes
Like other snakes go to hibernate in specific months to save their energy to survive the winter period, dice snakes go into hibernation between October and April. The snake species mostly prefer to hibernate in areas that are close to water sources.
The location of hibernation is determined by factors such as the anthropogenic structures within the area, such as water. Dice snakes select burrowing holes that are at least 4 meters above the average level of water. The snakes hide in higher grounds to avoid drowning during winter, especially if they are hibernating close to a lake or river. The hibernacula are expected to maintain the dice snakes at an average temperature of between 4 and 10 degrees Celsius even when the outside temperature falls below the freezing point.
6. Eyelash Viper
As with all vipers, eyelash vipers are venomous and inject venom into their prey using their long hollow fangs. This species inhabits a variety of habitats from wet forests, dry deserts, coasts, swamps, rainforests, and rocky places.
Eyelash vipers prefer to live a solitary life and interact only during the mating season. They are among the few vipers that hibernate during winter, where they accumulate in large numbers in the same den with other snake species. The more they are, the better they manage to keep warm and survive the harsh cold conditions.
7. Four-Lined Snake
The lined snakes are found active between March and November. They burrow in rock crevices and other warm areas below the frost line during winter, where they come out to bask in April. After heavy rainfall, since it is cooler, the four-lined snakes spend most of their time at the surface. The four-lined snake is non-venomous and among the largest snakes in Europe.
The species is mostly found in Italy along the west coast, Greek islands, and coastal Croatia and Bosnia. Four-lined snakes prefer the Mediterranean climate, and they are mostly found in forests, woodlands, deserted buildings, and rodent burrows. Although they are mostly solitary snakes, they will be found hurdled up to create warmth that will help them survive winter during hibernation.
8. Garter Snake
Since they are heterothermic like other reptiles, garter snakes regulate their body temperature by basking in the sun before hibernation. These snakes are native to central and north America, Costa Rica, and Canada. Garter snakes migrate for long distances to their preferred hibernation sites, but they are mostly active during the day through a wider range of temperatures.
Garters hibernate between October and April, but they can be found basking on rocks through mild winter days. To ensure they stay warm during the winter, they lie together in hundreds to maintain minimum temperatures for survival.
When they get thirsty, garter snakes absorb moisture through their skin to remain hydrated, and since they cannot digest food in low temperatures, garter snakes do not eat during hibernation. To prepare for the dormant season, they store body fat before winter. Garter snakes transfer heat through kleptothermy, which occurs immediately after hibernation to make them more active.
9. Grass Snakes
Grass snakes are typically brown or dark green in color with a characteristic yellow collar. The snakes are found in Europe and range from Italy to Scandinavia. Grass snakes prefer to feed on amphibians, but they occasionally feed on larvae and ants. Since swimmers are actively found wandering close to freshwater bodies, and their preferred habitats are the woodland borders and field margins.
The hibernation period of grass snakes occurs mostly between October and March. It is common for grass snakes and adders to hibernate in the same frost-free sites to prevent them from freezing during the winter period. During hibernation, grass snakes use fallen trees, rabbit warrens, compost heaps, and other warm and humid areas to regulate their body temperatures. Immediately after hibernation, grass snakes bask together close to their hibernation sites to warm up their bodies.
10. Hognose Snake
A distinct characteristic of the hognose snake is the upturned snout that assists in digging through soil. This snake species varies in color with a coating of black, green, orange, and white marks. Their prey consists of rodents and lizards, and they swallow them whole without necessarily constricting them.
The burrows made by the snake are used to hibernate from late October to early April. During the brumation period, the snakes cool down and maintain their body heat to ensure they survive the winter. They rarely go out to hunt or look for water unless in situations where it is necessary.
These snakes are mostly found in America and inhabit the southeastern part of Canada. The snakes are white, yellow, and others black. They are opportunistic feeders who constrict their prey. Kingsnakes are immune to venom, and they prefer reptile prey. Kingsnakes are found around river valleys, pine forests, woodlands, hillsides, and rock tops.
Over the winter, kingsnakes are known to hibernate, and they find habitats in rock crevices, mammal burrows, stumps, and hollow logs. During the inactive period, the snakes react to disturbance by coiling their bodies and heads to produce a rattling sound. The snakes hibernate between three and four months on an empty stomach.
12. Pine Snakes
These snakes spend most of their lives underground burrowing to avoid predators and harsh climatic conditions. Pine snakes are mostly found in New Jersey, North Carolina, Tennessee, North Alabama, Georgia, and Virginia. As its name suggests, the snake is mostly associated with upland forests such as pine woods and dry forests.
Through the winter season, the snakes hibernate underground from October to early April. They are known to hibernate twice a year, with the second hibernation period emerging during the fall.
13. Vipera Berus
While common European adders are solitary animals, they huddle up during hibernation to maintain a minimum temperature in an attempt to keep warm.
These adders can be found hibernating in pre-existing underground areas communally in their hibernacula between September and October. The Vipera Berus is known across Europe as being the native venomous snake that lives in bushy slopes, stone quarries, dumps, and wood edges.
The snake prefers wetlands, especially along ponds, rivers, and lakes, to maintain their body temperature during the hot season. These adders lie in crayfish burrows, mammal burrows, and tortoise burrows, holding an estimate of 100 hibernating snakes. Research shows that many adders remain active all year long if they live within mild climates, which favors movement and reproduction.
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Why Do Snakes Hibernate?
Snakes brumate because, during the cold seasons, they cannot control their body temperatures, and as a result, their body systems shut down. Therefore, they have to remain dormant if they are to survive and make it through.
During hibernation, serpents lower their temperature, reduce breathing, metabolism, and heartbeat to use little energy. Crucial body functions then use the stored fats to keep them warm enough to survive winter.
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Where Do Snakes Hibernate?
In the wild, snakes hibernate in warm and humid places, such as burrows dug by rodents and other animals. They also dig into tree trumps, rock crevices, and tree stumps. Abandoned caves are also a favorite for reptiles during hibernation.
Since the snake requires enough safety and warmth, they will select hiding areas that will not be disrupted by rain or the wind during hibernation.
Snakes are adapted to hibernate during winter in warm and safe sites such as caves, woodpiles, tree stumps, and burrows. Through hibernation, the snakes lower their metabolism and survive with their bodies’ least energy. Examples of snakes that hibernate include garter snakes, rattlesnakes, and copperheads.
While others undergo brumation, snakes in cold environments hibernate between September and early April, depending on how severe the winter becomes. Once the weather becomes tolerable, the snakes come out, and some species breed almost immediately.
Joe is a freelance writer for FaunaFacts. Joe has written extensively about snakes for the site, but also contributes content about a range of animals.