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Rattlers on the Rocks

Posted by | August 23, 2008

Campers, ranchers and us aging geologists all come across our share of rattlesnakes on warm days.

Although my reflexes are generally slower in middle age than they were in my distant youth, hearing the dry sound of a rattler still makes my adrenalin levels instantly soar. So I stand in awe of scientists who can calmly capture and study rattlesnakes, people like biologist Ken Kardong of Washington State University.

Kardong has studied reptiles for decades, with a special interest in venomous snakes. He knows how rattlesnakes strike their prey, what their venom does inside an animal, and how the snakes find their prey after the victims have run off to die.

As an expert in the rattlesnake research community, Kardong is in touch with the news from around the west about snakes, and he’s heard from scattered reports that the current season for rattlers in the inland Northwest is a significant one.

Studying and handling rattlesnakes for a living has some obvious hazards. Kardong has been seriously bit on two occasions over the decades, recovering both times with the help of anti-venom injections.

What you may have learned as a child about treating snakebites with razor blades, tourniquets or nooses of fishing line is far from the recommended practice today.

“Anyone who is bit should calmly go to the nearest hospital,” he said. “That’s all you should do. The doctors will evaluate how much venom you have received from the bite, and treat you accordingly.”

About 20 percent of bites to humans are “dry,” meaning no venom is injected. At the other extreme, about 20 percent of bites to people involve a big dose of poison. The remaining events fall in-between.

One aspect of Kardong’s research involves how rattlers sense their prey. They can see light, of course, but they can also sense infrared radiation using small pits located below their eyes. Infrared radiation is given off by any warm body.

“So the snakes can see in the daylight, but also locate prey at night or in underground tunnels using the infrared,” he said.

The venom of rattlesnakes does more than kill the prey. It also acts as a digesting enzyme so that when the snake swallows the dead prey, it’s digested from the inside out – from the venom – as well as from the outside in – from stomach juices. The system works so thoroughly that what the snake finally expels is often only the prey’s teeth and hair.

After striking a rodent with its fangs, a rattlesnake immediately throws itself off the prey, so that it’s not mauled by the rodent’s incisors. That’s a good strategy in terms of avoiding injury to the snake, but it means the prey is likely to scamper away before dying, giving the snake the significant task of relocating it.

The snake’s tongue helps it to track the dying prey. The flicks of the tongue bring back scent particles that are deposited in an organ in the snake’s mouth that registers them.

“Rattlesnakes can be as good or better than bloodhounds in trailing an animal,” Kardong said.

Speaking of dogs, man’s best friends have been known to get their noses bit when they sniff a rattler. Some bird-hunters have enough experiences along those lines that they leave Fido home until the later parts of the autumn. I don’t hunt, but I often walk my dogs along the aptly named Snake River. Luckily my canines feel unsure of how to respond to snakes. Thus far, their indecision has always allowed me to call them off the rattlesnakes we occasionally meet.

If you have lousy luck and are bit by a rattler, brace yourself for your hospital bill. The modern anti-venom drug is very effective, but exceedingly costly. If you want to avoid a charge of tens of thousands of dollars, it would be useful to give rattlesnakes a wide berth when you meet one in the great outdoors in what remains of the summer.

The most common snake-bite victim in the Northwest is a young male stopping on the highway to pick up a snake he thinks is dead. In the world of snakes, looks can be deceiving.

Apart from young men seeking trophies and geologists engrossed by their rock samples, the people Kardong thinks are most at risk of rattlesnake bites are bird-watchers.

“They are looking up, not down,” he said with a smile.