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On a foggy, cool morning earlier this fall, wildlife biologist��Chris Ray and PhD student��Rachel Mae Billings sat down at the edge of a rock-strewn mountain slope and listened — just listened. All was quiet aside from the scratching of pencils in field notebooks, the occasional chickadee twitter and, most importantly, squeaking pikas.��

Chris Ray writes in a field notebook beside rocky pika habitat near Mitchell Lake in the Indian Peaks Wilderness on Sept. 13, 2025. (Gabe Allen)

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Pikas — small herbivorous mammals related to rabbits — are easily recognizable by their staccato, piercing calls. They squeak to warn others of impending danger, shoo away neighbors that stray too far into their turf, and attract potential mates.��

Some day in the future, Ray and Billings hope to use these vocalizations to study the animals on a scale never before possible. Their collaboration began with this goal in mind — if you could find a way to distinguish between individual pika calls, you could gather more information with an audio recorder than was previously possible from a full day of trapping.

“My life would be so much easier if I could just take a microphone out and sit in each territory and get a few calls.” Ray said. “Then I could go back and sit on those same rocks and see whether I get the same individual next year.”

Heralds of change

Ray has studied pikas since 1988, when she was an undergraduate student at the University of California, San Diego. Over the past 37 years, she has amassed countless days in the field.��

Much of her work has focused on how climate change is impacting the diminutive mammals. Pikas are adapted to rocky slopes high in the mountains, where it stays cool through the summer. As temperature and precipitation has shifted across the American West, some pika populations have become small and isolated, or even disappeared. Others, like the populations here in the front range, have remained stable despite showing signs of stress.

predicted that warming temperatures could extirpate pikas from large parts of their current habitat by the end of the century. But, those same researchers are continually learning more about how the animals adapt to environmental change.��

“I’m interested in whether or not that’s actually happening,” Ray said. “Pikas are really good at finding microclimates that suit them.”

To answer these questions, Ray has continued monitoring pika populations across the American West. Each year, she returns to the mountains to trap the animals and collect health, survival and genetic data with help from a rotating cast of collaborators, volunteers, field technicians and students.

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Acoustic fingerprints

When Billings asked Ray to mentor her through her PhD candidacy, Ray saw an opportunity. She knew, from spending time with the animals, that individual pikas sounded slightly different from each other. Billings, who previously studied electronics engineering and is doing a PhD in quantitative biology, had the skills to develop technological tools that could identify those differences.

“She has the right background to work on a bioacoustic project — and she’s really good at it too,” Ray said.��

This summer, Ray and Billings began making audio recordings of pikas that had previously been trapped, tagged and characterized. The next step will be to try to find “acoustic fingerprints” within these recordings. To do this, Billings will analyze digital visualizations of the calls. She may even employ machine learning tools to assist.

Chris Ray and Rachel Billings check a pika trap near Mitchell Lake in the Indian Peaks Wilderness on Sept. 13, 2025. (Gabe Allen)

“If you look at a graphical representation of a pika call, known as a spectrogram, it sort of looks like a thumbprint,” Billings said. “The goal is to collect enough recordings to see, are these really unique enough to tell them apart?”

If Billings can unlock an acoustic fingerprinting technique, the research potential is great. Already, the team has stationed solar-powered audio recorders that passively record pika calls at field sites on Niwot Ridge.

“We have terabytes of acoustic data from Niwot Ridge already,” Billings said. “The hope is to eventually use that data to infer population trends and track individual survival from year to year without observing and tagging them through an invasive trapping process.”

Of course, acoustic fingerprinting is, for now, theoretical. This winter, Billings will hang up her field gear and spend her days behind a computer working out the methodology.

But, even if it doesn’t work, Ray, Billings and their collaborators are trying other noninvasive methods to expand their pika observation powers. One option is to analyze pika scat for “DNA fingerprints,” a technique that is becoming cheaper as genetic analysis evolves.

A third project, which has been ongoing since 2010, leverages Coloradans’ fondness for the animals.�� employs teams of volunteers to keep track of pikas around the state. And, as of 2022, citizen scientists can upload observations to a mobile app called .��

No matter the method, their goal is clear. To better understand these charismatic little mammals, and safeguard their future in a changing environment.

“The pika has been singled out as one of the animals more sensitive to climate change,” Ray said. “We're trying to find out how they survive in some of the most challenging climates on earth, and whether they're nearing their limits.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.