Why is California Seeing a Surge in Rattlesnake Bites?

It’s 2026 in California, and rattlesnakes are out in full force. The venomous snakes of the United States are among my favorite internet wormhole fodder. At eight years old, I found a rattler coiled up in a chicken coop and didn’t get bit. Although it scared the shit out of me, it also instilled a healthy reverence for them. Most of California’s rattlesnake species are desert dwellers, though others practically live in our backyard, sometimes literally. Encounters are inevitable as urban expansion brings us into direct contact with their native habitats. Children, the elderly, and people allergic to snake venom are likelier to face complications from a bite, including death. California averages one death per year by snakebite. This year, three people have died while hundreds more sustained serious, often permanent injury because of bites from the venomous reptile. 

But why so many bites so early on, and what kind of rattlesnake are you most likely to meet? 

Rattlesnakes inhabit almost every corner of the Lower 48. Alaska is too cold. Hawaii is too far a swim (they are actually excellent swimmers). The swampy Southeast is home to Earth’s largest rattlesnake, the Eastern Diamondback. Timber rattlers, colloquially known as Canebrakes in the South, have the widest range: Gulf Coast, Appalachia, Mid-South, eastern Plains. This species is the snake most abused in Pentecostal snake-handling churches. Their range also overlaps with Eastern Diamondbacks, with whom they’ve been known to hybridize. Prairie rattlers extend well outside their namesake’s High Plains habitat, deep into the Rockies and Desert Southwest. They’re the only venomous snake in Montana. Timber rattler populations are thin if present in states like Maine and Rhode Island, where these snakes are said to be extirpated. 

But unlike Maine and Rhode Island, California is rife with rattlesnakes. The state is home to seven recognized species. We have the second-highest species variation behind Arizona’s 14. From rugged Coast Ranges and inland plateaus up north, to the seaside scrublands and interior deserts down south, California is rattler country. If you count subspecies, that bumps our variety of vipers up to thirteen. 

Rattlesnakes have lived in North America for millions of years, evolving their species and venom variations as their range expanded. A snake’s venom profile reflects its typical prey. Five kinds of venom exist; five unique kinds of fucked up. Thankfully, our rattlers have mostly these two types. 

Hemotoxin destroys red blood cells and kills tissue. It works immediately and is, as I’m sure you can imagine, horribly painful. Survivors say it feels like being injected with liquid fire. Hemotoxin is insanely effective on us warm-blooded critters whose bodies readily circulate the venom. The bitten limb swells to cartoonish sizes that might look funny if it weren’t pure agony. The majority of California rattlesnakes, like the Northern Pacific, possess primarily hemotoxic venom. The same is true of their cousins, the copperhead (Agkistrodon contortrix) and the cottonmouth (Agkistrodon piscivorus), which do not live in California. 

Neurotoxin, as its prefix suggests, targets the nervous system, causing paralysis and respiratory failure. Interestingly, while the bite might hurt, neurotoxic venom (especially pure) doesn’t inflict as much agony as its hemotoxic counterpart. Instead, it renders you immobile and reduces your breathing until you suffocate, and you are conscious for pretty much all of it. It is highly effective on cold-blooded animals (lizards, amphibians, fish, other snakes), which metabolize much more slowly than mammals. Coral snakes (Micruroides, Micrurus) are the only US snake whose venom is purely neurotoxic, and they do not live in California. Few California rattlesnake species possess this type of venom. 

When Julian Hernandez died from a snakebite he sustained on February 1, scientists noticed. It was considerably early for rattlesnakes to be out of hibernation. Traditionally, rattlesnakes didn’t emerge from their winter dens in Southern California until March or early April. “We have seen a warmer spring than in past years,” Ventura County fire department spokesperson Andrew Dowd told the Guardian in April after the sixth snake-related death. “We had heavy rains this winter, and this is a time when snakes are typically out anyway and people are out on the trails, enjoying the outdoors.” 

Rattlesnake bites and related fatalities lend just one example of the ancillary, proximate effects of climate change. Rattlers in Southern California’s warm climate do not truly hibernate. Rather, they undergo a process called brumation. They still den together in droves, but they aren’t in full slumber. If hibernation is like deep sleep, brumation is a good nap. They can wake on especially warm days and sun themselves before dipping back belowground. Persistently warmer weather tells their bodies it’s time to emerge from brumation. Julian Hernandez died during a heat wave that produced Southern California’s warmest February on record, but heat didn’t kill him. 

Let’s conjecture using what we know about the food chain. While California warms with the rest of the world, it also becomes more suitable for rattlesnakes. Brumation periods could wink out of existence altogether, making rattlesnakes active year-round. More snakes would mean more snakes as booming populations compete for food. A hungry snake is a cranky snake, and more likely to strike impulsively. Then again, birds of prey feast on juvenile and young adult snakes. It might balance itself out. The fact of the matter is that snake encounters are normal, a sign of a healthy ecosystem. We just might see a few more than we’re used to.