(CNN) — Talk about a heavenly day: The Blue Ridge Mountains of North Carolina, temperatures in the low 70s and low humidity.
Scott Vuncannon, a 58-year-old real estate developer and farmer, called his wife and said he was going hiking and would be back around 4 p.m.
He packed his safety gear, including a pistol, bear spay and enough food and water to last a couple of days, just in case.
He grew up traversing the Uwharrie Mountains in central North Carolina. Now he was taking on more formidable wilderness from his summer home in Highlands, a popular resort town. Still, he had decades of hiking experience.
With a 2-year-old Australian shepherd-blue heeler mix named Boone at his side, he headed to the Ellicott Rock Trail around 11 a.m. Wednesday in late August 2018.
Two hours later, he was five miles in.
"My dog took off chasing a squirrel, and I stopped and took a sip of water," Vuncannon recalled to CNN Travel. "I called my dog ... and he came headed back over. And as soon as I took a step, I saw movement."
With no warning, "I saw a snake head come up and strike me in my left calf. ... My natural reaction was to jump back, and I bent over and pulled up my pant leg to see if he actually penetrated my long pants."
Vuncannon saw two bite marks about 2 inches apart. Boone went after the snake, and only then did Vuncannon hear rattling.
He tied on a tourniquet below the knee and above the bite. "As soon as I stood up, I could actually taste the poison in the back of my throat."
His vision got blurry, and he sweated a lot. "I pulled my phone my out and called 911, and of course, it said no cell service."
"That's when my heart sank."
With no phone service, no human companions and the venom spreading rapidly, how would he survive?
How dangerous are rattlesnakes to us?
Rattlesnakes are found only in North and South America, but their range within the Americas might surprise you. Here's a sign warning of them in Grasslands National Park in southern Saskatchewan, Canada.
Vuncannon was in known rattlesnake country. Their range is extensive in the Americas -- from southern Canada to central Argentina.
The thickest concentration is in the US Southwest and northern Mexico, according to the National Wildlife Federation. The estimated 36 rattlesnake species are adaptable, living in forests, grasslands, swamps and deserts. They may take up residence where people live and work.
But for their range, US deaths from rattlesnake bites and other venomous snakes are quite rare.
The US Centers for Disease Control and Prevention estimates about 7,000 to 8,000 people are bitten by venomous snakes in the United States each year. About five of those people die.
"The number of deaths would be much higher if people did not seek medical care," the CDC says.
World estimates for death by venomous snakebite are much higher -- 81,000 to 138,000 a year.
The pit viper family
Rattlesnakes are part of the pit viper family of venomous snakes. They have "cousins" in the United States that don't have rattles on their tails. At left is a copperhead, notable for its tannish-coppery color. At right is a a cottonmouth named for its distinctive white mouth.
Rattlesnakes are "pit vipers" with heat-detecting pits on their heads.
Other US snakes in that family are copperheads and cottonmouths, also called water moccasins. These latter two species are concentrated in the central and eastern United States, whereas multiple species of rattlesnakes range across the United States.
A look at the types venomous snakes that bite as many as 8,000 people each year in the US.
Most pit vipers typically deliver a "hemotoxic" venom that attacks the circulation system, destroying blood vessels and causing tissue damage.
The only other venomous snakes in the United States are coral snakes. Known for their bright bands of red, yellow and black, they are in a different snake family that's related to cobras. They deliver a neurotoxin that disrupts nerve transmission and can cause respiratory failure and paralysis.
You're scared? So is the rattlesnake
This Mojave rattlesnake was photographed in Arizona. It has one of the most potent venoms among rattlesnakes. Despite their fearsome look, these reptiles fear humans and would rather be left alone.
Rattlesnakes' reclusive nature is one reason why there aren't more incidents.
The rattlesnake "actually views us as a predator; we're a large animal that could eat him. And they're afraid of us," said Ted Clamp, who founded the Edisto Island Serpentarium in coastal South Carolina in 1999 with his late brother.
Rattlesnakes tend to stay hidden.
"When we encounter a snake on the move, he's usually looking for food or looking for a mate or looking for shelter. Otherwise, he stays hidden because they're so vulnerable to all sorts of predators."
Kimberly Andrews, who has a doctorate in ecology from University of Georgia's Marine Extension and Georgia Sea Grant and manages its Coastal Ecology Lab, said rattlesnakes are "sit-and-wait predators."
"I've seen rattlesnakes sit in one place for over a week waiting on a meal."
So when there's an encounter, people have generally encroached on their territory.
Where rattlesnakes hide
As with other types of rattlesnakes, the western diamondback is a master of camouflage. Whether you're in the Southwest's deserts or deep in the Appalachians or in brushy coastal areas, keep a sharp eye out.
Nature Picture Library/Alamy Stock Photo
Rattlesnakes "hunt shelter constantly. They hide under these logs. They hide in stump holes -- under anything they can," Clamp said.
They also like woodpiles, thick brush and spaces under boulders, experts say.
Clamp cited a case of a 12-year-old South Carolina boy playing at a log pile who got bit by a canebreak (timber) rattlesnake. He lived but only after a six-week hospital stay.
Rodents are much more likely to get into your house than snakes, Andrews said. If snakes do get into your house, it's most likely you have a rodent infestation.
Andrews said rattlesnakes play a key role in balancing the environment.
"They're mostly eating mice and rats. ... They're out there doing free pest control," she said.
How to avoid a bite
This rattlesnake would have a very hard time penetrating this handler's boot. Experts say you should never wear open-toed footwear while hiking in known rattlesnake territory. Long pants are a good idea, too.
Clamp and Andrews shared advice on how not to be a statistic.
"Always be careful where you put your hands and your feet," Clamp said.
"If you have a woodpile, go out and get your wood for the night during the day when you can see," Andrews added. Wear thick gloves.
"If you're reaching under your house, shine a light under there. Make sure the coast is clear," she said.
• Wear closed-toe shoes and long pants when venturing into rattlesnake-friendly terrain.
• Go around a rattlesnake on a wilderness trail if possible.
• If you find a rattlesnake in your yard, call agencies such as your state's natural resources departments or US Fish & Wildlife or contact a biologist at a local college, Andrews said. Do not try to kill the rattlesnake because that's when most people get bit, she said.
• If you must deal with a rattlesnake on your own, Andrews says you can use a long branch or pole to gently nudge the snake toward an escape route if you're at least six feet or more away.
Andrews said rattlesnakes are most active in spring and fall, but vigilance is important all year. They might venture out in winter on a warm day.
What do you do if you hear that bone-chilling rattle?
"Usually if he's rattling, he's alarmed," Clamp said. "If you can tell where he is and see him, back away from him. Don't approach him." Just know rattling does not come before every bite, as in Vuncannon's case.
In dire straits
Vuncannon knew he had to get out. "I slowly, methodically started walking up the mountain, a pretty steep climb."
He had only gone about a quarter of a mile when he lost his balance. He started crawling.
Vuncannon was throwing up about every 15 minutes. Then he started to go in and out of consciousness.
"My dog stayed with me the whole time. He never left my side. He would paw at me and lick me in the face to keep me awake."
About two hours after being bit, he fired a shot from his pistol into the air to get attention. Nothing.
Back in Highlands, his wife had a gnawing feeling something was amiss. She found his truck at the trailhead around 4:30, and returned to town for help. Around 5:30, a rescue attempt was finally underway.
"Just so happens around 5:30, I had pretty much given in that I wasn't going to make it out alive. So I went ahead and made a goodbye video to my family with my phone. I recorded about a three-minute video; I couldn't talk clearly because my throat was so swollen."
It was getting dark, and Boone start to growl. Vuncannon saw a black blur moving his way and feared a bear was coming to finish the rattlesnake's job.
What to do if a rattlesnake bites you
A western diamondback rattlesnake is milked for venom at a rattlesnake roundup in Kansas. The venom is then used to help produce antivenom to treat snakebites. If you're bitten, the venom from a rattlesnake begins to digest the flesh, causing intense pain and swelling.
Thad Allender/Lawrence Journal-World/AP
"If you are bitten, you need to seek medical attention as quickly as possible," Clamp said. "If you know it's a really serious bite, you should probably call EMS to come get you."
"You'll know if you have a serious bite in just a couple of minutes. ... You can start to feel tingling in your face."
• Extreme pain and swelling at the bite
• Lots of bleeding
• Nausea, lightheadedness and drooling
• Swelling in the mouth and throat
And if you can't make that SOS call?
"Keep your heartbeat as low as possible. It takes a while for the venom to work. Don't run. [But] get yourself somewhere you can get a signal as soon as possible," Clamp said. "There's nothing to really help you from the venom except the serum."
The snakebite victim should stay as calm as possible and deep breathe, Andrews said. If someone can stay with the victim, that person should talk to them and keep them from falling asleep.
Take notes or voice record on a smartphone what happened, she said. If possible, use a marker or pen and circle where you were bitten in case of swelling. They'll need to know the bite point at the hospital.
Remove jewelry such as rings and tight clothing before you start to swell, the Mayo Clinic says.
What not to do
Andrews said don't employ the out-of-date Boy Scout advice of cut-and-suck (cutting an X at the bite area and sucking the venom out by mouth or suction cups).
"It's very ineffective," she said, adding people are likely to do more damage from the knife cut than from the snake bite.
Don't try to kill the snake to bring to the hospital, Andrews said, and don't take a picture of it unless you can do so easily. "Don't comprise your safety by forcing another interaction with an already defensive rattlesnake."
Clamp, Andrews and other experts say do not apply a tourniquet to a pit viper bite (which is something Vuncannon did).
That venom is "concentrated, and it works like an acid. It breaks down blood vessels and multiple skin tissues," Clamp said. "And if you confine that venom in that area, you're apt to lose a limb from that. If you allow it to spread, you're more apt to keep your hand or fingers."
In updated advice, the Boy Scouts and other experts say don't apply ice or cold packs to the bite and don't use Advil, Motrin or other nonsteroidal, anti-inflammatory drugs.
Clamp and Andrews said your response should be the same no matter which type of pit viper bites you.
"The best emergency response to a snakebite is car keys and a cell phone," Andrews said.
Vuncannon's rescue and recovery
Scott Vuncannon (center) is pictured near the end of his 14-day recovery at Mission Hospital in Asheville, North Carolina. Here, he's with Cheryl Taylor (left), one of his trauma care physician assistants, and Lois Hancock, a flight medic who intubated him to keep him alive while en route to the hospital.
Fortunately, that was not a bear Vuncannon saw but a rescuer's black lab. However, it was getting dark, and Vuncannon was getting worse.
A helicopter couldn't be used because of the thick canopy. Vuncannon was too far gone to be slowly carried out. So he was moved by motorcycle, strapped to a driver and held up by paramedics walking on either side. That took three hours.
More than 11 hours after he first got bit, he made it to Mission Hospital in Asheville, but he had already gone into cardiac arrest.
Doctors had bad news for his family. Vuncannon had less than a 5% chance to survive.
His rescue was one miracle, and he needed a second one. He got around a dozen antivenom treatments and other medical interventions.
Vuncannon was in a coma for three days but pulled through. "It took me a total of about three months to fully recover enough to where I could actually walk and have the energy to get around."
He later learned it was a timber rattlesnake that bit him and that it directly hit a vein, which made the venom spread more rapidly but later spared him from tissue damage.
What Vuncannon learned
He's back on the trails, but he carries a satellite phone, especially on deeper trails.
He's also more likely to find someone to hike with him. If he goes alone, it's on wider, well-maintained trails.
"And I also carry hiking poles with me to brush the side of the trail just in case. Let someone know exactly where you're going, when you'll be back."
He now has three grandchildren.
"I look forward to teaching them about the wilderness and the outdoors and how to avoid snake bites and dangerous encounters."
Steve Ludwin's unique activity began as a hobby, but now he hopes that his self-immunizations will one day help snake bite victims.
Andrews applauds learning about snakes, so that you can keep your family safe and "actually enjoy a venomous snake sighting, something that is comparatively rare and can be pretty special."
Clamp pointed out pit vipers can be lifesavers, too.
They're important to us "because a tremendous amount of research has been done with different venoms," noting some FDA-approved, lifesaving drugs are derived from snake venom.