Relocated prairie rattlesnakes face mortality, weight loss in Wyoming state park study

Emily Martin didn’t grow up thinking she wanted to study prairie rattlesnakes in the foothills of the Rocky Mountains.

That she may one day be slipping radio transmitters into the body cavity of a living rattler to learn about its movements and life habits wasn’t on Martin’s bucket list.

The U of I doctoral student who spent several years researching small mammals and birds such as rabbits and quail didn’t consider snake research until the opportunity arrived.

She grabbed it. Gingerly first. With snake tongs.

Martin’s research through the College of Science and College of Natural Resources Idaho Cooperative Fish and Wildlife Research Unit will determine if snakes return to an area after they have been moved — or translocated — and measure their chance of survival in their new territory.

“If a rattlesnake gets into an area in the park where it can’t stay, like a well-used hiking trail or a visitor parking lot, often those animals get moved to another place,” Martin said.

A long-standing policy at Sinks Canyon State Park in Wyoming, where she is conducting her research, requires rangers to move snakes to the edge of the park away from humans if the animals are found in too close proximity to humans.

Martin’s goal is to assess what happens to a snake once it is moved.

“Does it come back? Does it continue to pose a problem? Does it die? All these are questions that we’re tackling with this project,” she said. “We are interested in answering a more management-focused question and collecting data that can help manage rattlesnakes.”

The prairie rattlesnake range starts at sea level with many populations, such as those on the middle of the Great Plains, at elevations around 3,500 feet. Sinks Canyon State Park’s elevation is between 6,500 and 7,000 feet.

“It is pretty high, particularly for how far north it is compared to a lot of other rattlesnake habitats,” Martin said. “It poses a lot of challenges for these animals to be able to survive over winter. And they have a short, active season.”

Martin’s research starts in spring after the snow leaves the area and wraps up for the year around September when the snakes become less active.

During summer, her days start with a game of rattlesnake hide and seek.

She and fellow researchers hike on a route through the park where snakes live, often on southerly slopes of rocky outcroppings where snakes bask in the sun or hang out to catch food, like small mammals and lizards.

“We walk, and you’ve got your eyes on the ground,” she said. “But I would say it’s probably 60% of the time you hear the rattle before you make visual contact with the animal.”

Unless it’s cold, and the snakes don’t rattle.

“If it’s really cold, often you have to just use your eyes and you get really good at picking out rattlesnake patterns underneath rocks and in the vegetation,” she said.

When a snake is located, researchers bust out the snake tongs.

“They’re like what your grandma uses, those grabbers to get things out of the cupboards. It’s the same concept,” she says. “We'll grab a snake with the snake tongs and put it in a sack or pillowcase and then place it in a bucket.”

The two-layer containment system prevents the snake from escaping.

At the researchers’ headquarters, usually a travel trailer, snakes are anesthetized, and transmitters the size of a Mike and Ike candy are placed in the rattlesnakes’ body cavities away from internal organs, so they don’t impede normal snake functions and movement.

“Every snake gets a unique three-color code that prevents us from catching the same snake over and over,” Martin said.

Snakes that receive transmitters are kept overnight to make sure they breathe and function normally before they are released to their home territory or moved to a new location approximately a quarter mile or more depending on protocol.

After two field seasons, Martin’s data shows that translocated snakes don’t return to the trouble spots from which they were removed.

“Although the snakes don’t appear to return to their home territory, they move around their landscape, around their habitat in really profoundly different ways from non-translocated snakes,” Martin said. “That is good news from a human perspective. If you’re removing the snakes from the area, that lack of a homing mechanism is really valuable.”

On the other hand, the research shows that snakes don’t do well once they are taken from their home range and dropped into unfamiliar territory.

“The downside from the snake perspective — we did see increased mortality,” Martin said.

Researchers also documented weight loss in translocated snakes which could spell trouble for animals that need to overwinter in a harsh climate.

“These are low energy specialists that may eat one to four times in an active season, so any kind of weight loss can cascade,” she said.

Her research shows that moving snakes away from humans but still within their home range may be the best solution for both people and the rattlers.

“Likely that’s something we’re going to recommend for the park,” she said.