What ground squirrels can tell us about climate change

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Researcher Caitlin Wells has spent the last 15 years studying the behavior of golden-mantled ground squirrels at the Rocky Mountain Biological Laboratory in Gothic. Photo: Alexis Kikoen, Rocky Mountain PBS.
Rocky Mountain PBS will be covering the Rocky Mountain Biological Laboratory as part of production for "Colorado Experience" season 11. ‘Gothic’s Outdoor Science Lab’ airs October 24th. 

GOTHIC, Colo. — In the very early summer, when the snow finally melts in the East River Valley near Crested Butte, the first of the golden-mantled ground squirrels emerge from their burrows after hibernation.

And where there are golden-mantled ground squirrels, there is Caitlin Wells.

Wells is the co-lead of a long-term study — almost 35 years strong — on the behavior of golden-mantled ground squirrels at the Rocky Mountain Biological Laboratory (RMBL). She’s spent the last 15 summers studying the behavior of generations of ground squirrels.

Wells’ co-director, Dirk Van Vuren, founded the research project in 1990 as a behavioral ecology study — to discover why some animals live in groups, like marmots, another animal observed at RMBL, while others live on their own, like ground squirrels.

As researchers have studied the ground squirrels’ behavior over the course of 34 years, they couldn’t ignore the changes in their environment. At that elevation, the climate has changed noticeably over the years, with higher temperatures and drier conditions. 

“Over the years, as is the case for so many of the studies here, this has become a climate change study,” Wells said. “[We] have the opportunity to use all of this long term data to see how changes in climate are impacting this particular species.”
The study discovered that ground squirrels will shift their behavior to adapt to changing climate conditions, like emerging from hibernation earlier if the snow melts sooner.

Wells and her team tag and track female ground squirrels to see how these behavior changes will affect the population over time. 

For example, when ground squirrels spend more time above ground due to warmer temperatures, they’re able to eat more and gain more mass to get through their hibernation. But they also spend more time exposed to predators, which threatens their numbers.

The golden-mantled ground squirrel population this year is tied for the lowest ever recorded over the course of the study, with five adult females. Two years ago, the population was around 23 adult females. Predation and human impacts, such as cars, played a role in that decline.

Golden-mantled ground squirrels are small — about the size of a baked potato — but significant, and their resilience is important to the overall ecosystem. They create more nutrient-rich soil by burrowing and spread seeds by foraging. They’re foundational to the food chain, and many animals in the valley rely on them as part of their diet.
Ground squirrels look more like chipmunks than tree squirrels, the bushy-tailed tree-dwellers often seen in more urban areas. Ground squirrels have the striped backs and skinny tails of chipmunks but have calmer personalities. Photo: Alexis Kikoen, Rocky Mountain PBS.
Ground squirrels look more like chipmunks than tree squirrels, the bushy-tailed tree-dwellers often seen in more urban areas. Ground squirrels have the striped backs and skinny tails of chipmunks but have calmer personalities. Photo: Alexis Kikoen, Rocky Mountain PBS.
Every summer, when Wells makes her pilgrimage to Gothic to revisit the valley’s golden-mantled ground squirrels, she contributes to nearly a century of research at RMBL, which was founded in 1928. 

“We have multiple generations of knowledge about how all the different parts of this ecosystem work, and that gives us a really solid foundation for predicting how things are going to be in the future,” Wells said.

“The more we can draw these links between what's happening with climate and what's happening with our natural world and humanity in general, I think the more people are convinced that we need to act.”