It’s 7 a.m. as Katie Pfaff steps into a wooded corridor in Bagley Nature Area, a 59-acre wilderness on the University of Minnesota Duluth (UMD) campus. A chorus of birdsong fills the tree canopy above and dappled sunlight marks the trail ahead. Pfaff, a student in the Integrated Biosciences Graduate Program at UMD, is on her way to check a series of live traps for flying squirrels.
“We’ve got a flyer,” she says, peering into a small cage mounted five feet up on the side of a large tree. She carefully removes the cage, sets it on the ground and covers it with a towel so the squirrel isn’t overly stressed.
Pfaff is part of a research team led by Michael Joyce, PhD in the mammal ecology lab at UMD’s Natural Resources Research Institute (NRRI). The team is studying northern and southern flying squirrels whose distributional ranges are increasingly overlapping due to climate change. The area of overlap, or “zone of sympatry,” aligns with the wooded areas around UMD’s campus, allowing these researchers quick access to their fieldwork sites.
“Lots of people don't even know that there are flying squirrels in the Duluth city limits and potentially right in their backyards,” Pfaff said.
And that makes sense because flying squirrels are nocturnal, only coming out at night. They’re much smaller than the gray squirrels that raid your bird feeders and tease your dogs. They can fit in the palm of your hand and have large eyes that allow them to navigate the forest at night.
Northern flying squirrels in particular, Pfaff said, distribute ectomycorrhizal fungi throughout the forest, which supports the growth of native tree species. As climate change brings southern and northern flying squirrels closer together, researchers are concerned about potential hybridization, parasite transmission and overall competition of resources.
“We're really just trying to see what the outcome of that competition will be, if they're able to coexist in the future in Minnesota, or if we might need a protected status for the northern flying squirrels,” Pfaff said.
Pfaff has been equipping flying squirrels with radio telemetry collars for the past year in an effort to map their home ranges and nest sites. To date, she’s collared over 20 flying squirrels and is hoping to reach 50 by next summer. She checks traps early in the morning and returns to the forest late at night to track the squirrels she’s collared. The timing of the work, she said, allows her to take classes and work as a teaching assistant during the day, and still get out in the field to fulfill her research. She admits it can be tiring, but “worth it for the squirrels.”
At the end of the study, Pfaff's research will be combined with other researcher’s data and provided to the Minnesota Department of Natural Resources to help inform future management decisions for flying squirrels in the state.
Back in Bagley, Pfaff and a fellow graduate student work together to carefully weigh and measure a flying squirrel. They point out the furry membrane, or patagium, that stretches between its wrists and ankles allowing it to glide through the air. After taking measurements, they determine this one is too small to collar, so they release it on the side of a tree and watch it skitter 20 feet up. From there, it briefly surveys its environment before springing from the tree. The squirrel quickly stretches its legs away from its body, pulling its patagium taut between its legs like a parachute. It uses the sudden increase in lift to gracefully glide to a nearby tree, a special moment that usually only happens under the cover of darkness.
In many ways, the UMD campus itself is a zone of sympatry for climate-related research–a place where students and researchers like Pfaff operate at the fringes of the day in search of answers to questions arising from shifts in our environment.
“I think it's really important for a place like the University of Minnesota Duluth to have such a breadth of research going on, looking at such specific things like the flying squirrels of Minnesota, but also other aspects of climate change,” Pfaff said.
Project funding was provided by the Minnesota Environmental and Natural Resource Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).