Rattlesnakes are among America’s most dangerous reptiles. As such, it’s crucial that you find out when are rattlesnakes are most active and know how to avoid them.
Snakes are good at adapting to different conditions. That’s why you can find them on every continent, barring Antarctica, and anywhere north of the Arctic Circle. They’ve adapted to desert environments by learning how to avoid the heat. And they’ve adapted to colder habitats by avoiding frosty nights. Let’s find out more about how rattlesnakes adapt to their environment.
Are Rattlesnakes Nocturnal or Diurnal?
Rattlesnakes are nocturnal, diurnal and crepuscular. Nocturnal, as you know, means that they come out at night. When a snake’s nocturnal, they’ll do all of their activity at night—it’s not just that they’re ‘comfortable’ being out in the dark.
They’ll hunt, mate, explore, lay eggs and more during the night. These snakes will then rest during the day, hiding in dens or just in some shade. During the summer, rattlesnakes are nocturnal.
Diurnal is the opposite of nocturnal. It means that something is active during the day, like we generally are. Again, they’ll do all of their activity during the day, but sleep at night.
Crepuscular means that an animal is active at dusk. Rattlesnakes are crepuscular throughout the spring, summer, and fall. That’s because the temperature isn’t too hot and it isn’t too cold.
Why Do Rattlesnakes Come Out at Night?
The reason why rattlesnakes are often nocturnal is that they need to regulate their temperature. Snakes are cold-blooded. This means that they don’t generate their own body heat.
Instead, they rely on the heat of the sun for many things:
- It helps them digest food (you need heat for the acid in your stomach and the bacteria in your gut to be able to break down food)
- It stops them from getting too cold, which can make them sick
- It helps their muscles to warm up, which quite literally helps them move more quickly
So, if they like the sun so much, why do they come out at night? Surely that doesn’t make any sense? Well, it does—because the midday summer sun is too hot for them.
They can’t regulate their temperature in any way, either by heating themselves or cooling themselves down. If they get too hot, this causes all sorts of health problems that they’d rather avoid. So, when it’s too hot during the summer, they’ll only come out at dusk and night.
But during spring and fall, it’s warm enough that they can be active but not too hot either. Then, when it’s too cold, they’ll retire to their den for the winter. At this point, they don’t come out at all.
Do Rattlesnakes Hunt at Night?
Yes, they most definitely do. All snakes rely on their sense of smell for hunting, detecting chemicals in the air that draw them closer to their prey.
They use their tongue to flick the air, catch these chemicals, and then use special organs located in their nose to figure out where the smell is coming from. This helps all snakes hunt at night.
But rattlesnakes are pit vipers, which means that they actually have an added advantage. According to a paper in the journal Nature, not only are they exceptionally good at smelling their way around, they have an extra organ—an infrared heat-sensing pit.
These pits are tiny holes on their face, in which there’s a thin membrane. This membrane can detect the most minute changes in heat. They can use these pits to detect the warmth of a mouse, rat or another prey item up to three feet away.
Rattlesnakes are ambush hunters. This means that they lie in wait for prey to come to them, rather than chasing it down. All they need are their heat-sensing pits to hunt, even if it’s completely dark. Of course, during the day, they can use both their vision and their heat-sensing pits to sense prey.
Can Rattlesnakes See at Night?
They can, but rattlesnakes don’t entirely rely on their vision to sense the world around them. Like the raptors from Jurassic Park, rattlesnakes don’t see sharply defined objects.
Instead, their eyes are sensitive to movement. This is because they lack something called a ‘fovea,’ which is a small pit inside the eye. The fovea is responsible for very focused and detailed vision, like when you’re reading.
As for whether they can see well at night, they definitely can. That’s because they have plenty of ‘rods’ in their eyes. If you didn’t know, eyes work because of different kinds of cells. These are rod cells and cone cells.
Rod cells are far more sensitive to light than cone cells, which means that they’re almost solely responsible for night vision. With just a tiny amount of light from the stars and the moon, rod cells help you see clearly. Cone cells, on the other hand, help you see in color.
Because rattlesnakes have lots of cone cells in their eyes, their night vision is excellent. They also have quite a few cone cells, too, so scientists are sure that they can see in color. All that they’re lacking is the detailed vision that we have.
What Temperature do Rattlesnakes Become Active?
Rattlesnakes brumate from late fall up until early spring. You’ll start seeing them come out in late March or early April. There is no precise date when they all come out.
Also, some snakes will start becoming active earlier than others. However, the springtime is mating season for rattlesnakes (and all other U.S. snakes) so expect to see plenty out and about. Once temperatures start to head north of 60 degrees, you’ll start seeing some rattlesnakes.
During the summer, you can expect to see them in the morning or at dusk. They’re happiest at 80 or 85 degrees, so early mornings and dusk during summer days are fine for them. But when the temperature hits higher than 90 or 95, rattlesnakes have trouble regulating their temperature.
Beyond that, a temperature of 105 or 110 would kill a rattlesnake in minutes flat. So if it’s hot out, there won’t be any rattlesnakes bothering you. If they’re not in their dens, they’ll be catching some shade under a cactus, a log, or whatever else is around to cover them.
Rattlesnakes will start to become less active the colder it gets. If you’re in timber rattlesnake country, which includes the north even up towards Canada, these snakes might brumate from September onwards when temperature dip below 60.
Eastern or western diamondbacks will hibernate later, because temperatures stay warmer for longer. You might also see them sunning themselves during periodic warm weather in late fall and winter.
Where do Rattlesnakes Go When They’re Not Active?
Rattlesnakes have dens, more appropriately termed hibernacula, where they go to escape the cold or heat. For rattlesnakes, these are usually accessed through gaps or cracks in rocks. During winter (or unusually cold nights), it’s crucial that their den is below the frost line.
The frost line is the depth of ground below which soil, or anything else, doesn’t freeze during cold weather. If the snake has to endure freezing temperatures, they won’t survive. So, they head into deep dens to stay alive.
Rattlesnakes have favorite dens. They head back there year after year when it’s time for them to hibernate. Scientists aren’t exactly sure how they remember where their den is, but they think it might have something to do with pheromone trails.
But what might surprise you is that they share their den with dozens, sometimes even hundreds of other snakes. They all huddle together, hardly moving. You can even find other species entirely in there, like other reptiles and even small mammals.
According to USA Today, during hot weather, rattlesnakes will do anything they can to find shade during the day. It’s a matter of life and death for them. So, they’ll hide in rock crevices, under bushes, and in long grass. They’ll wait there throughout the heat of the afternoon and start to venture out again when it gets cooler out.
If you’re worried about encountering rattlesnakes, remember these rules:
- Don’t approach the snake if you think it might be a rattler
- If there’s one in the path ahead, take another path
- Don’t poke your hands or head into an enclosed space in rocks, in hollow logs, or similar
This is the time of year when you’re most likely to encounter a rattlesnake, because they’re hiding in easy-to-access places. In the summer, rattlesnakes hiding in long grass often ‘encounter’ people’s lawnmowers, which doesn’t end well for anyone.
And people resting on a rock after a hike might be in for a less restful time than they bargained for, since they accidentally disturbed a snake. But follow those three rules, and you’ll be fine.