PRESS-ENTERPRISE (Riverside, California) 14 April 05 Rattlers -- Via radar: As Inland post-drought snake boom slithers to life, expert snoops on how they eat, sleep, live -- and bite (Darrell R. Santschi)
Victorville: It's springtime in San Bernardino County's High Desert. Wildflowers are in bloom. Creosote bushes are thick and lush. And the Mohave rattlesnakes that nest here are on the move.
Mike Cardwell, a 54-year-old retired San Bernardino County sheriff's deputy, is on the move, too. He is using surgically implanted radio transmitters to wrangle and research Mohave greens, a reclusive species of rattlesnake known for its lime-green tint and the extraordinarily toxic venom it packs in its fangs. Measured in terms of the amount of venom it takes to kill laboratory mice, the Mohave is the most lethal rattlesnake in North America.
Cardwell is completing a pioneering four-year study of its eating, breeding and biting habits.
His research may help scientists who are using rattlesnake venom to make medicines for treatment of everything from heart disease to breast cancer.
It also helps hospitals determine how much expensive antivenin they need to stock to treat snakebite patients.
He has learned that the snakes are more active in a wet year than during drought years. And that they breed not one season a year but in both fall and spring.
In a wet year like this one, that adds up to a slithering stampede.
"When these snakes move, it's almost like clockwork," says Dr. Sean Bush, an emergency room physician at Loma Linda University Medical Center. "I'll get a call or an e-mail from Mike saying the snakes are moving like crazy. What I'll see that same day or the ensuing days is a rash of snakebites."
Cardwell's data suggests to Bush that this will be a big year for Mohave bites.
"What that allows you to do is make preparations," says Bush, who appears on the cable television program "Venom ER." "We know that our pharmacy needs to stock more antivenin. That's not a small issue. Antivenin costs $900 a dose. Some pharmacies can't afford to stock it."
Cardwell, who has never been bitten, is busy in the desert this week capturing the last of the 20 rattlesnakes he implanted with tracking devices. He will spend the months ahead compiling data on the secret lives of Mohave rattlesnakes and writing reports for scientific journals.
In Arizona this weekend he will be a speaker at a conference for biologists. In January, he was a featured attraction at a symposium on rattlesnakes attended by more than 300 scientists and medical professionals at Loma Linda University.
Cardwell says he's been a fan of wildlife and the outdoors all his life.
Cardwell injects an anesthetic into a tube to put a Mohave Rattlesnake to sleep before removing a transmitter.
"I've always been fascinated with creatures that most people are, in my view, unreasonably afraid of -- bats, sharks, snakes -- creatures that people are fearful of out of all proportion to the true public health threat," he says.
That dates to an incident when he was in first grade, nearly half a century ago, when his mother's cat dragged a king snake into their Los Angeles home.
"It was alive and mom was just terrified of the snake," Cardwell recalls. "I was amazed. I thought the snake was very cool and I didn't understand why she was so afraid of it. I kept it for a long time."
The family moved to the Apple Valley-Victorville area, where he graduated from Victor Valley High School in 1968. He then enrolled at Victor Valley College as a biology major.
"I soon realized that there were a lot of unemployed biologists around," he says.
At the urging of other friends, he enrolled in the community college's justice administration program and earned associate degrees in that and biology. He volunteered with the sheriff's rescue team and then, in 1972, hired on as a deputy. In the ensuing 32 years, he worked his way through the department, serving as commander of the Apple Valley station and eventually as chief of a 200-member special operations unit that includes homicide detectives, the SWAT team, the bomb squad and the search-and-rescue team.
But he never gave up his interest in biology.
"There have been a lot of studies of other rattlesnakes, but nobody has ever taken on the Mohave," he says. "It's interesting because there are places like here where they are very common."
While Loma Linda and Arizona State universities provide equipment and computer software, Cardwell pays his out-of-pocket research expenses.
An antenna and transmitter are removed from a snake that is part of the study.
He wanted to study the Mohave rattlesnakes' lifestyle.
"There is so much myth and rumor and misinformation about the Mohave," he says. "People think they are the most dangerous rattlesnake. A big Mohave can inject a respectable amount of venom and they can make you really sick, and people do occasionally die from them, but only a fraction of 1 percent of snakebite victims die in the United States. Most of the deaths occur in places where there are no Mohave rattlesnakes."
The last rattlesnake bite fatality in San Bernardino County was two years ago, he said. It was from the bite of a Southern Pacific rattlesnake in Lytle Creek.
But humans are far more lethal to the rattlesnakes than the snakes are to humans, he says.
Most snakebites are defensive, he says.
"Imagine living your life an inch off the ground and having something 6 feet tall come along and mess with you."
Cardwell has captured and studied 81 Mohave rattlesnakes in a square-mile desert area north of Victorville. He has implanted radio transmitters in 20 of them.
The transmitter is the key to his research. The cylinder weighs 9 grams, about as much as a double-A battery, and measures about three-quarters as long. Attached to it is a wire antenna about a foot long. A signal emitted by the transmitter can be picked up with a hand-held, H-shaped antenna from as far away as 200 meters.
It not only leads the researcher to the snake, it can take its temperature. That led to Cardwell's discovery that the cold-blooded snakes stock up enough heat in the daytime to look for romance at night with temperatures in the 50s.
"The technology is not new," Cardwell says. "They've been making little tiny radio transmitters for several decades. What is getting better every year is the ability to make tiny little batteries that will last long enough to matter."
Batteries now last a year.
"You can't put a collar around a snake like you could a bear or a mountain lion," he says. "You can't glue it to a shell like you could a tortoise or a sea turtle. The snakes shed their skin, so you can't glue anything to them. The only practical way to follow them is to put a transmitter inside of them."
The 20-minute surgery can be done in a motel room. Cardwell coaxes the rattlesnake's head into a clear plastic tube with a piece of gauze taped over the opposite end. He injects a breathable liquid anesthetic into the gauze and within 10 to 15 minutes, the snake is unconscious.
Cardwell uses scissors to cut a half-inch-long incision on the snake's side, about four-fifths of the distance from its head to its rattle.
There, relatively safe from the snake's vital organs, he slips the transmitter between fat and bone. He uses a tiny, rigid tube to stretch the antenna forward under the skin, then stitches the incision closed.
In the field, Cardwell's receiver emits a beeping noise -- using a different frequency for each snake. The sound gets louder as he gets closer to the snake and softer as he turns the antenna from side to side.
"You learn very quickly to keep checking behind you," he said.
Sometimes the snakes get curious and come looking for him.
He shows a photograph he took of a Mohave rattlesnake curled up and camouflaged just inches from his toes.
"I was tracking the snake and I made a circle around a bush," he said. "I was getting a strong signal and I thought it was in a burrow right under me. Then I saw it was laying on the top of the ground right under me."
He didn't get bit.
It was all in the name of research.
As Inland post-drought snake boom slithers to life ...