In grade school science class, we learned that snakes, like all reptiles, are cold-blooded animals (ectotherms). This classification doesn’t mean that they’re impervious to icy conditions. In fact, ectotherms need more external assistance to regulate their internal body temperature.
Any temperature below 65°F (18°C) is too cold for snakes. When it gets too cold, snakes struggle to maintain vital body functions that keep them alive, like metabolism and digestion. They’ll brumate, find winter dens, and huddle together to thermoregulate when faced with cooler temperatures.
This article will explore why snakes dislike cold temperatures and what they do during colder seasons. I’ll be focusing on rattlesnakes for this discussion.
What Temperature Is Too Cold for Rattlesnakes?
Any temperature below 65°F (18°C) is too cold for rattlesnakes. Cold-blooded animals cannot internally regulate their body temperatures, so they rely on external heat sources. When it gets cold, they’re deprived of that necessary external heat.
According to a press release by ScienceDaily, rattlesnakes like it better when it’s hotter.
While their average body temperature is between 70 and 74°F (21 and 23°C), they’ll gravitate towards spaces that’ll let them achieve a body temperature of 86-88°F (30-31°C).
How Rattlesnakes Thermoregulate
As ectotherms, rattlesnakes’ body temperatures change according to their environment. They must seek external heat sources to keep their body temperature at the desired 70°F (21°C) for coastal rattlers and 74°F (23°C) for inland rattlers.
Using External Heat Sources To Warm Up
Their most convenient source of heat is the sun. You’ll often find rattlesnakes sunbathing to bask in that sweet heat. They’ll automatically retreat to the shadows when they’ve soaked in enough UV rays.
When the sun is out for longer, rattlesnakes are in proverbial heaven. They have more time to hunt and enjoy their spoils. They can also sustain critical bodily functions for longer before going into power-saving mode.
Employing Energy-Saving Methods To Stay Warm
During the colder seasons, rattlers prioritize using as little energy as possible since there’s not much heat available. To this end, they employ strategic behavioral adaptations, which we’ll look into below.
Brumating To Conserve Energy
Unlike mammals, rattlers don’t hibernate. Instead, they brumate, dramatically reducing their metabolic activity when it’s cold.
During brumation, rattlers eat very little or not at all. Fortunately for them, they don’t need much energy to survive. Male rattlesnakes can live on about 600 calories yearly, equivalent to consuming a ground squirrel.
Sometimes, rattlesnakes stuff themselves as a roundabout way of achieving endothermic heating. As digestion proceeds, the metabolism rate rises proportionally. This process allows brumating rattlesnakes to stay warm when external heat sources are absent.
Creating Winter Dens
Within rock outcroppings in the Rocky Mountains and the Sierra Nevada Mountains, rattlers will identify and then cozy up in winter dens.
Chilling in these rocky south-facing winter dens gives them the heat the rocks previously absorbed. These locations are their best bet for warmth in an icy expanse. For similar reasons, small rodents love these areas, so that’s a double win for the rattlers.
They’ll remain brumated in their dens for as long as needed to stay warm against the harsh elements outside. Going out on warmer days serves two purposes: catching a bite to eat and absorbing as much heat as possible.
Isolated spaces underneath residential homes are also attractive winter dens for rattlers.
Huddling
Rattlesnakes will huddle together in their winter dens of choice.
Doing so results in impenetrable insulation that bolsters the warming they are trying to achieve. Lone snakes can also curl up alone for a muted version of the communal huddle.
Interestingly, different snake species regularly band together when it’s cold outside.
Combining these adaptations enables rattlesnakes to survive in regions that experience extreme temperatures. They’ve irrefutably earned their resilient reputation.
Risks and Rewards of Being the Hottest Snake on the Block
Warm weather may benefit rattlesnakes but also carries its own risks.
Warm weather ensures rattlers can hunt and eat for longer while keeping them at the toasty 86-89°F (30-31°C) they like. Still, rattlers extracted from the wild have lower body temperatures than their counterparts who’ve been in the lab.
Optimal Body Temperature Helps Rattlesnakes Regulate Their Bodily Functions
Snakes can’t digest their food, undergo metabolism, or even reproduce if it’s too icy outside. They’ll go out of their way to soak in the heat from their surroundings, which typically involves “sitting” in the sun.
By doing this, they get life-supporting heat and can manufacture vitamin D. This vitamin is responsible for strengthening the rattlers’ bones and supporting metabolism.
Basking Puts Rattlesnakes at Risk of Bigger Predators
Rattlesnakes are formidable predators, wreaking havoc on small rodents in their ecosystems. There’s always a bigger fish, though.
When rattlesnakes are out basking, they expose themselves to predators like coyotes and hawks. It turns out that being the hottest rattlesnake in town is quite a dangerous affair. It’s a risk rattlers will avoid if they can.
Conclusion
Snakes rely on the temperature of their environment to determine their internal temperature. So, temperatures below 65°F (18°C) are not just uncomfortable for these slithering serpents but can also be deadly. Snakes will try to find efficient ways to gain and retain heat during winter.