Why California's rattlesnake population is booming

California lost 117,552 human residents in 2021, but it gained tens of thousands of new residents that love the state's increasingly hot and arid climate.

Rattlesnakes are thriving here, according to a recent joint Cal Poly San Luis Obispo and University of Michigan study, which reveals that the seven species of rattlesnakes found in California are among the fastest growing animal population in state. Why? It's the same answer that may be driving some to leave the Golden State altogether: climate change.

The snakes are thermoregulators, which means they are able to change their own body temperature to suit their surroundings. Coastal rattlesnake species have internal body temperatures of around 70 degrees, and their inland counterparts average around 74 degrees, the study says.

But as California gets warmer, the rattlers find that they can get to more comfortable body temperatures, like their preferred range of a toasty 86 to 89 degrees Fahrenheit. In the study, researchers said the increase in number of snakes in California can affect the ecosystem. Rattlesnakes play an important part as both predator and prey. They help regulate the population of ground squirrels, and also serve as food for owls, hawks and eagles.

"A warmer climate may help these snakes heat up to temperatures that are more optimal for digestion or reproduction," said Hayley Crowell, a University of Michigan student researcher and the project's lead, in a statement.

What a rattlesnake actually sounds like

When I relocated to the Central Coast a decade ago, a trail running friend told me to enjoy the many unexplored coastal switchbacks and easily accessible ocean view peaks. But then he gave me a word of caution: watch out for rattlesnakes.

I laughed. I thought he was kidding.

He wasn't.

Over the years, I've caught glimpses of rattlers sunning themselves here or there or slipping in and out of the brush when they feel my approach. And unlike your co-workers who claim to be one right before inviting you out to drinks — rattlers are nature's true introverts. They are notorious for trying to avoid trouble and wanting to be left alone. But once in a while, when agitated or surprised, they'll ball up and give you their signature warning.

The first time I heard the rattle go, it was ... surprising. It doesn't sound like it does in the movies. Instead of a steady low maraca shake, it's more of a high-pitched buzzing similar to an old brick Nokia left to vibrate on a tabletop — quick and urgent and annoying. When you hear that noise, my running friend said, run, don't walk, in the other direction.

That advice has served me well over the years as I've seen a rattler here or there. I've only gotten close because from a near distance, they closely resemble dead manzanita branches in the middle of the trail. I even unwittingly strode over one who was having a midday siesta, only to turn around when the warning buzz started up in my wake.

This spring thus far, however, has been a different story. Since April 1, I've had four rattler sightings, and there's more to come — at least according to one expert.

"In California, the climate is perfect," Len Ramirez, owner of Ramirez Rattlesnake Removal, told me earlier this week on a quick break between jobs. He's busier than ever as the snakes started to come out of hibernation in droves last month. "It's getting warmer. There's development moving into more remote, previously undisturbed areas — that's a part of it, too. I'm so busy, it never ends. I can't even cut my lawn. Once the season gets going, it's nonstop."

Ramirez, who lives in Auburn and has been in the snake wrangling biz since 1985, travels up and down the state to help people or businesses mitigate their rattlesnake issues, always releasing them back into the wild. He says he's seeing rattlesnakes crop up in new areas all the time, noting that more coastal regions like Marin, Sonoma and Monterey counties — places where he never saw snakes in the 1980s and '90s — are starting to see population increases. And places like the Bay Area and the Tahoe corridor (towns along Highway 50 between Sacramento and the lake) are becoming rattlesnake boomtowns.

"In these spots where there is so much development near wildlands, everybody's got a story, everybody's got a sighting," he says. "People don't like to have snakes around their yards or around their pets, small children — but at the same time, they build houses on rock piles or in areas that run up right against open space or wildlife. And when that happens, we're going to have encounters."

And while he's worked some of the bigger metros like Sacramento or Bakersfield or Fresno, there is one place Ramirez says he's never received a call: San Francisco. The city is cut off from the wildlands of Marin and Alameda counties and still has a marine layer that creates a cooler climate that is suboptimal to the vipers, two factors that are central to the snakes' lack of presence in SF proper, the snake wrangler explains.

"That's not to say that someone might accidentally take one home from camping — those things do happen," he says. "But in San Francisco, unless you go visit the Academy of Sciences, you won't see one — which is good for those folks."

'If they feel threatened ... they'll defend themselves'

But what happens when you do see one?

"That's a great question," says Ken Paglia, a spokesperson for the California Department of Fish and Wildlife who, like rattler wrangler Ramirez, says that rattlesnake population in California is growing and vipers are now found in previously rattlesnake-free, or at least sparsely rattlesnake-populated areas. "There are some basic safety tips we share, but a lot of it comes down to awareness."

Paglia says people should stay on trails and watch where they're stepping. Avoid rock, wood and other debris piles. Store wood away from the footprint of your house and if you do see one, give it space, don't poke it or stay and have a staring contest. "Given the opportunity, they'll move away, but if they feel threatened or prevented from escaping, they'll defend themselves."

And never, ever step in places where you can't see, he says.

"It's really about paying attention to your surroundings."

What you should do if a rattlesnake bites you

"I always say the best immediate rattlesnake bite treatment is your car keys and your cellphone," Ramirez says.

About 250 Californians a year are bitten, according to the LA County Public Health Department. Those who do suffer a bite should stay calm, gently wash the wound, keep it level or below the heart and go immediately to their nearest emergency room or medical stop for further treatment, the Mayo Clinic says. Do not apply suction to the wound, further lacerate it or apply open flame to it.

Californians will likely encounter rattlers outdoors this summer

This is the first summer in two years where Californians are planning to hit the road and go exploring, fish and wildlife spokesperson Paglia says. This means there might be a lot of wild habitat that has been previously left alone during the height of the pandemic, so native animal populations — including rattlesnakes — may be prolific.

Rattlers are also thriving because they live on less. The Cal Poly-University of Michigan study says these vipers need only 500 to 600 calories per year, the equivalent of a single ground squirrel or half a Chipotle burrito, no guac, to you and me.

Because they love the current climate and we've built on or trudge around their turf, the chances of a rattler encounter loom ever larger, Ramirez says.

It's good to remember, he says, that we're the ones on their turf.

"I got a million hits on my website in early spring," he concludes. "They're everywhere and people are thirsty for knowledge. They deserve to be here, and we're treading on their territory. They don't know if it's your house or garage. They don't know you're out for a hike. They're just trying to exist and when you come into contact with one — which is increasingly more common — just start by giving them the respect they deserve."

Editor's note: This story was updated at noon, May 25, to correct information on what to do if you are bitten by a rattlesnake.