Time-lapse cameras used in a multi-year scientific study are recording the natural activities of hundreds of venomous prairie rattlesnakes living in a network of rock dens in the middle of Routt County.

Snake researchers have documented that more than 1,000 rattlesnakes over-winter together in a hibernation den about the size of half a tennis court located on private ranch land west of Sleeping Giant, or Elk Mountain.

The goal of the local research is to learn about the secretive reptiles living in remote areas through time-lapse photography of snake rookeries where the female rattlesnakes come together to give birth and care for their young, said study co-leader Emily Taylor, Ph.D., professor of biological sciences at California Polytechnic State University. Taylor works alongside fellow herpetologist Scott Boback, Ph.D., a biology professor at Dickinson College in Pennsylvania.

The researchers are inviting locals to assist with the rattlesnake study as citizen scientists. People can sign up with Project RattleCam on the “people-powered research” website Zooniverse and then help record snake behavior shown in thousands of time-lapse images.

“It is really difficult to reach areas where rattlesnakes aggregate like this, both logistically and physically, so our project has the added bonus of making this footage accessible to people from around the world,” said Taylor, who worked at the project site for three weeks this summer.

The study results will help researchers learn more about rattlesnake social behavior, water gathering skills and common snake predators such as red-tailed hawks, magpies and bobcats. The team submits for research permission each year through Colorado Parks and Wildlife.

One of the most interesting findings so far since the game cameras were installed in spring 2020 is that female snakes help fellow moms babysit for the young snakelets (the name for a baby snake) when the moms need a break underground, Boback said. The prairie rattlesnake is abundant across many areas in Colorado and can give birth to four to 12 snakelets per reproductive cycle.

“We believe the females are interacting and socializing with each other. When they give birth in August and September, we think that they babysit for each other,” Boback said. “We believe they have this really interesting social dynamic among pregnant females.”

Professors Boback and Taylor started the joint research project in 2017 and have since implanted small radio transmitters about the size of one AA battery along with a 7-inch antennae under the skin of 40 live snakes, and 25 transmitters are still functioning. The transmitters show, for example, that male snakes leaving the den in spring can travel more than 3 kilometers within 24 hours, which even impressed the seasoned snake biologists. The researchers also insert microchips into individual snakes for identification purposes.

The researchers, including college students, set up the time-lapse cameras to operate 365 days per year and have documented how the snakes come out of the dens together to catch water on their backs during rainstorms. The snakes coil and flatten their backs to catch water that they then drink off their bodies.

“We are interested in behaviors like rain harvesting and interactions between mothers and babies at the rookeries,” Boback said.

The male snakes and nonpregnant female snakes leave the hibernation den in early June, traveling out in all directions. The pregnant mothers move about 200 yards to an area of big rocks where the researchers set time-lapse cameras to take photos every five minutes. When the mothers and babies move back to the den in late summer or early fall, the researchers move the camera back to outside the den entrances to take photos every 15 minutes.

Although Boback said there is no scientific evidence that rattlesnakes are increasing in numbers in Routt County, the research project does document the breadth and speed of the snakes’ travel.

Reports of the winter dens inside the crevices and spaces in the volcanic rock outcroppings have been documented for decades, including a story printed in 1925 in the Routt County Sentinel when a man from Boulder spent several weeks “making prisoners of about 300 snakes” to use for snake oil. Another regional spot to find rattlesnake dens is near Fortification Rocks north of Craig, Boback said.

The researchers say one common misconception about rattlesnakes is that they are aggressive, but Boback’s venomous snake research for the past 22 years shows rattlesnakes are not aggressive. The rattlesnakes only assume a defensive, coiled position with their head elevated and possibly shaking their rattlers when they feel threatened. In their natural state, rattlesnakes are docile.

The researchers are always very cautious and careful and wear tough boots and snake gaiters when working with the snakes, which can grow up to 3 feet and weigh more than 2 pounds. The researchers also place the rattlesnakes in clear tubes that safely restrict head movements.

The owners of the ranch where the snake dens are located are very supportive of the research project, but they’re not necessarily thrilled if rattlesnakes come up near their house. So, the researchers instructed the owners to keep the land around their home clean and clear with the grass mowed short and all snake hiding places removed.

“If you see a snake in the wild, the best and safest thing to do is to leave it alone, keep your distance and let it go past you,” Boback noted.

The researchers chose Routt County for the rattlesnake behavior study due to the large population den at 7,300 feet. That is a more extreme altitude for an over-wintering den of the ectothermic animals that need to warm up using external heat. The researchers hope to learn more with the addition of a grant-funded live webcam streaming to YouTube starting next spring.

“The snakes are part of the whole ecosystem and part of the heritage in the region. Snakes, specifically rattlesnakes, are one of the most misunderstood animals in North America,” Boback said. “If people would see these animals up close doing their natural behaviors, I think they would just be amazed at how interesting they are.”