Watch a livestream of Colorado’s ‘mega den’ of pregnant rattlesnakes

On a rocky hillside in Fort Collins, Colo., is a “mega den” of hundreds of rattlesnakes.

They live between the rocks year-round, but in the summer, the only snakes to remain in the area are preparing to give birth.

“So this is not quite what we might expect, like a black bear den or a grizzly bear den or something,” says Scott Boback, professor of biology at Dickinson College and co-leader of Project RattleCam.

“This is more like a rock face, where there's a number of holes that go underground — crevices and cracks in between the rock — and you will see snakes go in and out of these holes. We don't quite understand exactly what's going on beneath the surface.”

Project RattleCam, a research project based in California, is making it possible for people to observe the snakes with a live webcam. Cameras tucked away in the hillside livestream the snakes to their website.

Boback says this is an especially interesting time to watch the snakes because of their behavior during pregnancy.

Unlike other snakes, rattlesnakes give birth to live babies — or "pups" — and care for their young for a few weeks after birth. Typically, snakes live solitary lifestyles, but when they’re pregnant they coalesce around nurseries called “rookeries.”

“So when they are aggregated together, as scientists, you got to ask the question about why, what's going on,” Boback says. “And so that's one of the things that we're doing with the camera, is we are interested in how these animals may be interacting with one another. Like, do they tolerate each other?”

Project RattleCam permits Boback and his colleagues to observe the snakes without disruption. It also allows the public to participate.

“We're sort of right next to the general public who are helping us in that way by making certain observations,” he says. “They're identifying individual snakes. They can go back and they can rewind the video and they can stop at certain frames, identify unique features on an individual and name the snake. And that allows us to sort of move forward in tracking individuals.”

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Researchers from Project RattleCam understand some of the species’ strange behaviors, like rain harvesting, where the snakes coil up like a teacup and collect water in their body.

Other data is still being studied, but focuses towards the interactions of the mothers during their gestation period.

“If you have a whole bunch of expectant mothers together, they don't all give birth exactly at the same time,” Boback says. “Essentially, what you have is the opportunity for other mothers to babysit for the mother that actually has given birth to those pups.”

Boback says that observing these traits helps correct wrongful assumptions about the species.

In a study published by the journal Biology of the Rattlesnakes, Cale Morris, a researcher and educator at the Phoenix Herpetological Sanctuary, used a fake leg to mimic stepping on 175 rattlesnakes. In the entire study, only six snakes struck back at the prop.

In May, NPR visited the rattlesnake training course taught by Morris in Scottsdale, Ariz. He told the class: "I just want you to look at this for what it is. This is not an aggressive animal. I see a shy, scared animal."

Boback says there are many more mysteries to the social behavior of rattlesnakes, and RattleCam is adding insight to a neglected portion of zoology.

“The way that we have always measured sociality is often with primates,” he says. “Things like us, where we smile and we frown and we look at each other and have these very specific facial expressions."

"Because a snake doesn't do that, we maybe assumed that there is no socialization going on when, in fact, the snakes are getting a sense of smell from each other every time they stick their tongue out. And so there are chemicals in their skin that we believe they're using to understand each other. Who is who? They have a way, perhaps, of detecting each individual. Is this my sister? Is this my aunt?”