In a typically frigid and snowy New England winter, the natural world may seem to go dormant.
But if you’re willing to tromp through the woods in subzero temperatures, attaching game cameras to trees, luring small mammals with tubes of peanut butter, and measuring snow depth and melt, there’s plenty to discover about how plants and animals interact in a harsh environment when their mutual survival is at stake.
That’s why Caitlin Hicks Pries, associate professor of biological sciences, offered a new field-based course in winter term, End of Winter: Winter Ecology. It grew from a National Science Foundation grant that is also funding her winter snow-melt experiment at the Dartmouth Skiway.
With additional support from Dartmouth’s Campus As Lab fund, Hicks Pries and 11 students spent many cold days making observations in Pine Park, near the North End of campus. The class also used other wooded spots near campus, such as the Fullington Farm Trail, to learn winter ecology.
Pries asked three teams—one focused on large mammals and birds, another on small mammals, and another on climate—to ask probing questions.
“We wanted to understand how organisms survive winter,” she says. “What do they have to endure? What are the challenges they face and how does being cold-blooded versus warm-blooded affect those challenges? What are the strategies that organisms have evolved in order to get through winter?”
Hicks Pries, an avid skier, notes that winter—her favorite time of year—is the fastest changing season due to climate change.
“That’s an immense source of grief for me,” she says. “What does that mean about these animals and plants that not only have to overcome the challenges of winter, but in some ways can thrive in winter? And when winter’s gone, how does that affect them and how does that affect ecosystems?”
To find out, Matthew Monroe ’27, a biology major and member of the class’s small mammal team, helped set up an elaborate, snow-sheltered system, tying PVC tubes to stakes pounded into the ground and baiting the tubes with peanut butter and seeds. In the tubes, food-seeking creatures, including mice and voles, came in contact with sticky tape that the team hoped would capture their fur and help identify them. Unfortunately, the tape didn’t always work as planned in inclement weather, so Monroe based his final project instead on data collected by the other two teams.
“Basically every person had a completely unique study question and a unique way of analyzing the data, but most of us drew from the same two data sets,” he says. “So we were all working with pretty much the same stuff, but found totally different ways of looking at it from different angles, which I thought was really cool.”
The large mammal study group was luckier because they were able to rely on game cameras equipped with SD cards to collect data from 12 different plots in the forest: four in hemlock groves, four in meadow areas, and four in deciduous forest stands.
“Our cameras picked up herds of five or six deer—one or two moving through nibbling branches; a mother deer and her two fawns, which was adorable; as well as three deer prancing after one another through the snow of the meadow, which was great,” says Noah da Silva ’25, who majors in earth sciences modified by biology. “Also, we captured a number of foxes on both cameras, one coyote, one mink, one squirrel, and four unidentified animals.”
The team thought that deer might vary their movements depending on the depth of snow, but that didn’t seem to happen. Instead, says da Silva, the animals spent most of their time, whatever the weather or snow pack, in the hemlock grove, where they found food. And to get there, they carved out strategic routes.
“We realized that we had captured deer highways,” da Silva says. “A bit of an informal term, but deer will tramp down the snow and form trails that other deer will use.”
A native of Bermuda, da Silva says keeping warm as he collected visual data was challenging but rewarding, not only for him, but potentially for other users of Pine Park, which has been owned by the nonprofit Pine Park Association since its creation in 1905.
“That was a really cool moment where we discovered something that is actually kind of useful for the Pine Park Association,” he says. “Because now we know where the deer stage during the winter, and where their highways are. So the people who manage Pine Park might have an easier time of tracking, managing, and conserving the deer population in the area.”
Group three, studying climate, used remote sensors to measure temperature in the air, on the ground, and in the soil, as well as light levels and snow depth, at the 12 plots in Pine Park.
“Even from initial observations when we were choosing sites or doing equipment setup, you could already tell that there were some differences in air temperature,” says William Summit ’26, who is majoring in biology. “Being under the hemlock stands, you felt colder and you noticed a little less snow.” He says his research project found “a very convincing relationship between a canopy type and snow depth.”
The class also aligns with the Dartmouth Climate Collaborative and its Climate Futures Initiative, where President Sian Leah Beilock has called for using the campus as a lab to foster sustainability and address climate change.
All the findings were presented at the end of the term in a poster session, where students had to answer tough questions about their work, just as they would at an academic conference.
“That was real preparation, getting us ready for that environment,” Summit says. “There’s so much visual design and storytelling that I had never encountered before. It was a really good challenge.”
The course was also, all three students agree, one of the most exhilarating and enjoyable they have taken at Dartmouth.
Hicks Pries says she feels the same way.
“This is the most fun I’ve ever had teaching, and I hope to offer this class every other year,” she says.
The Pine Park sites have also become part of a winter climate change network for Dartmouth, where researchers will monitor snow, soil, and subcanopy and subnivean (the zone between the fallen snow and ground) temperatures throughout a latitudinal and elevational gradient.
