Rattlesnake project looks closer at South Table Mountain

By Kevin M. Smith
Special to Colorado Community Media
Posted 9/9/18

Ryan Borgmann looked at the ground confused, listening to the loud beeps on his radio. “It should be right here,” he said, pointing the antenna toward a small patch of tall grass. Then he saw it. …

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Rattlesnake project looks closer at South Table Mountain


Ryan Borgmann looked at the ground confused, listening to the loud beeps on his radio.

“It should be right here,” he said, pointing the antenna toward a small patch of tall grass.

Then he saw it.

Then the other researchers saw it.

The rattlesnake they were looking for was perfectly still less than two feet from Borgmann.

As of Aug. 16, a research team had captured, implanted a radio transmitter in and released 17 rattlesnakes on South Table Mountain Golden.

It’s a new phase of research after a similar project on North Table Mountain last year.

Jeffco Open Space contracted with Adaptation Environmental Services to conduct the study last year and continued that contract with a similar study on South Table this year.


The study was spurred by the concept to make the park more accessible and user friendly.

South Table is an unincorporated 844-acre park in Jefferson County, but Jeffco open spaces wants to make that mountain more accessible. Currently, one of the entry points is a gravel lot not large enough for a dozen vehicles in a residential neighborhood along Golden Hills Road. Jeffco is considering a building a larger, paved parking lot with restrooms there.

However, for visitor safety the county wants to avoid building near a snake den or snake habitat.

“With the population of the Denver metropolitan area continuing to increase every year, it is imperative to provide healthy, nature-based experiences ‘close to home’ at parks such as South Table Mountain Park,” stated the Jeffco Open Space master plan updated this past spring. “This is accomplished, in part, by balancing the recreation demands of visitors with the protection of natural and cultural resources on the property.”

Andrew DuBois, citizen science coordinator for Jeffco Open Space, said that also includes formalizing the trail system and eliminating the “social trails that crisscross.”

If Jeffco can reduce the likelihood of a trail going over or next to a rattlesnake den, it can lower the rate of human-snake interaction.

The study

Each rattlesnake collected goes to a lab where they make an incision to insert a thumb-sized radio transmitter, each operating on a different frequency.

“As long as we’re within a couple hundred yards, we should be able to hear it,” explained Borgmann, rattlesnake specialist with Adaptation Environmental Services. “It just puts off a little beep and you can triangulate the direction in which the snake is and as you get closer you can adjust some of the settings to get it narrowed down to exactly where they are. Usually we can get to within a foot of them pretty easy.”

Borgmann tunes to the frequency of the snake he wants to find, points an antenna almost half is body height and rotates it, listening for a beep. A beep indicates the correct direction, the louder the beep the closer he is.

“We play Marco Polo with the radio,” Borgmann said.

He would step, pause, rotate right, rotate left, step forward, pause, rotate, step, step, pause, rotate, step forward. This process would continue until the beeps were loud enough indicating the snake was nearby.

“This one is notorious for hiding, but he’s one of my favorite snakes," Borgmann said as he tracked another snake with the radio. “His colors are extremely contrasty, so everything is very vibrant.”

Yet, when the research team came upon him, the snake was difficult to see.

“He’s really good,” Borgmann said as he realized where his favorite snake was hiding. “He’s right behind this piece of grass.”

Researchers would like to capture a few more snakes to track, but in specific area. Currently, they have just one in the valley where the parking lot is proposed.

“We want to know, basically, are they going to den up nearby? What kind of movements are snakes making through that low valley?” said Bryon Shipley, research, training and outreach specialist for Adaptation Environmental Services.

He said they won’t know about their denning habits until November.

Currently, many snakes recently gave birth, which may make them a little “jumpier” than usual, DuBois said.

The snakes

Despite its bright green colors, another snake blends well on the gray rocks speckled with lichen.

Some curl up next to a patch of tall grass. Others hide under rocks.

“Rock outcrops are the rule of thumb here, that’s what they like,” DuBois said.

Even as researchers stand just a few feet away, the rattlesnakes are placid. Many, on a recent evening, were perfectly still in an “ambush” coil.

DuBois said they’re waiting for a rodent or other prey to wander by to strike. Contrary to some opinion, an upright posture while shaking its rattle is not the primary reaction to humans.

“This is a snake relying on his first and best defense: camouflage,” DuBois said.

The rattlesnake hopes humans don’t see it and if they do, that they won’t be a threat.

“This is the part you don’t see most of the time,” DuBois said.

Because they blend so well to their surroundings, many people might walk by a rattlesnake and never know it. So the snake freezes. If someone gets too close, the snake may flick its tongue — first quickly to capture a scent then more slowly and deliberate to assess the situation.

It’s when it then deems a person a threat that the rattle gives off a warning before adjusting its posture. DuBois noted, however, that steps in that process may be skipped depending on the snake’s personality or its assessment of the situation.


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