Published: July 2, 2021 By

Small mountain mammals like marmots and ground squirrels are experiencing the effects of rapid climate change.

In a 13-year study published earlier this year, CU ecologist and associate professor Christy McCain found that small mammals in Colorado’s Rocky Mountains are shifting their ranges to higher elevations in response to warming temperatures.

“For mammals and any living organism... a main determinant of where they live and flourish is climate,” said McCain, who is also curator of vertebrates at the CU Museum of Natural History. “They are very much evolved to live in a particular set of climates that allow them to live and reproduce successfully.”

During the past several decades, however, temperatures have been warming faster than many species can adapt. To stay within their niche climate, animals must follow the cooler temperatures up the mountain — shrinking the available area of their range.

McCain and her team studied 47 mammal species from the Front Range and San Juan Rockies, including the golden-mantled ground squirrel, pygmy shrew, pine squirrel and Western jumping mouse.

By comparing field data with museum records, they found these species have moved uphill an average of 430 feet since the 1980s. Montane mammals — those already living at higher elevations, like the yellow-bellied marmot — experienced the most dramatic changes, moving their ranges up an average of 1,135 feet.

“Some of [these species] might not be charismatic to everybody, like the tiniest shrew... but they’re indications of the wider biodiversity that’s changing in Colorado’s mountains,” said McCain. “If we don’t curb this change, our grandchildren might not see some of these species in the future.”

Despite the daunting challenges of a changing climate, McCain stays positive by focusing on what she can contribute through her research.

“I see it both as a person... and as a scientist,” she said. “There’s a lot that we can study. We can delve deeper into each species’ biology — and understand what might help them.”


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Photo from McCain Lab