Snakes do not “like” the cold; they are ectothermic, meaning their body temperature is regulated by external sources. This means snakes are highly dependent on their environment for warmth. When temperatures drop, snakes become less active and seek shelter, a survival necessity.
Understanding Snake Body Temperature
Snakes are ectotherms, often called “cold-blooded,” meaning they cannot generate their own internal body heat. Their body temperature fluctuates directly with the environment. Unlike mammals, snakes lack physiological mechanisms like shivering or sweating to maintain a constant internal temperature. Their activity levels and metabolic functions are directly tied to external temperatures.
To manage their body temperature, snakes employ various behavioral strategies, known as thermoregulation. They bask in direct sunlight or coil on warm surfaces like rocks to absorb heat. Conversely, if too hot, they seek shade, burrow underground, or retreat into cooler crevices. Most snake species function optimally within a preferred body temperature range, typically between 28 and 34°C (82 to 93°F). Maintaining this range is essential for their metabolic processes, digestion, and ability to move and respond.
How Snakes Cope with Cold
When temperatures fall and remain consistently low, snakes in temperate regions enter a state of dormancy called brumation. This differs from hibernation, a deep sleep state for warm-blooded animals. During brumation, a snake’s metabolism slows significantly, and its heart rate can drop to as little as 5% of its normal rate. They become less active and may not eat, as their slowed digestive system cannot process food efficiently.
Snakes prepare for brumation by ceasing to eat several weeks beforehand to ensure their digestive tracts are clear, preventing food from rotting internally. Triggers include dropping environmental temperatures and shorter daylight hours. To survive, snakes seek insulated shelters known as hibernacula, such as underground burrows, rock crevices, log piles, or communal dens. These locations must remain above freezing, ideally below the frost line. While in brumation, snakes are not in a deep sleep and may occasionally emerge on warmer winter days to drink water or bask briefly before returning to their sheltered spots.
The Perils of Freezing Temperatures
Prolonged exposure to freezing or near-freezing temperatures poses threats to snakes. If a snake cannot find a suitable hibernaculum that stays above 0°C (32°F), or if temperatures drop too rapidly, it risks hypothermia. Hypothermia manifests as extreme lethargy, decreased activity, and an inability to move effectively. At severely low temperatures, bodily functions can cease, leading to the freezing of tissues and organs, which is fatal.
Even if not immediately lethal, exposure to cold conditions can have non-lethal consequences. Snakes experiencing prolonged cold may become sluggish and unable to escape predators. Their immune systems can be weakened, making them more susceptible to diseases and infections once they emerge from brumation. Insufficient cold protection can also lead to frostbite or other tissue damage.