Biology major examines squirrel behavior

It’s not difficult to find students or alumni with a fascination for squirrels on campus at The College of Wooster. These quirky creatures have even become a popular Independent Study topic where students have often investigated the eastern gray squirrel population—one that includes black (melanistic) squirrels who are members of the same species, with a different “color morph.” But Lydia Crane ’25 is the only Scot who can claim “squirrel-catching experience” on her resume. Even though squirrels’ average lifespan is less than two years, Crane’s catch-and-release work has opened the door to new data for biology students for years to come. 

Crane knew she was interested in a field-based project on the ecology or wildlife side. She considered studying the frog colony in the Wooster greenhouse, but ultimately landed on a squirrel focus because she wanted to learn more about the campus population of black squirrels, which is rare in other places. She also knew she could learn from her mentor’s extensive experience with squirrels. Rick Lehtinen, Theron L. Peterson and Dorthy R. Peterson Professor in Biology, has published several studies on the animal, coauthored some with Wooster students, and advised various squirrel-related I.S. projects.  

Crane designed her study with two goals in mind: to assess whether there are any behavioral differences between the gray and black squirrels on campus and to assess any differences between the two in survival over time. 

With some trial and error, Crane caught and ear-tagged squirrels on campus with little metal numbered ear tags to come up with survival estimates. Lehtinen had never caught or tagged himself, but assisted Crane in her field efforts. They eventually switched to different color tags to tell each squirrel apart more easily. Crane collected tag data for three months. Squirrels were live-trapped and immediately released unharmed after tagging. 

“We know a fair amount about campus squirrel behavior, abundance, etc., and Lydia’s work helped deepen our knowledge on these topics, but it is really hard to tell one squirrel from another,” said Lehtinen. “To look at something like survival over time, you really need to be able to recognize individuals. Lydia’s livetrapping and marking work has allowed us to start to look at that.” 

Even though there wasn’t enough time to draw survival conclusions for her study, the data keeps adding to itself, so future student researchers will have more to work with. “I’m excited that the tagging project we started will continue for years to come,” said Crane. Lehtinen said they hope to add a social media aspect of the project where students, faculty, and staff can report tagged squirrel sightings to a social media page. 

To obtain her behavioral data, Crane spent two months observing squirrel behavior and activity through walking surveys. While walking between her campus house and the science building to and from class, she’d record the number of squirrels in each color, the weather conditions, and what behavior they exhibited. She examined the similarities and differences in behavior and activity levels in different conditions to understand the relationship between the color of the fur and animal actions like grooming, chasing, wrestling, or play, and more. The data also helped her gauge potential selective advantages in the environment that could be causing the frequency of the black squirrels in the population to change. 

Crane said her biology labs provided insight into the experimental design process and equipped her in reading scientific literature so she could ask strong scientific questions. One of the major hypotheses she found in science papers said black morph squirrels can survive better in the cold because of a thermal advantage, where they retain more heat. “Our data was inconsistent with that,” said Crane, adding that she also found a higher proportion of black squirrels active when the temperature exceeded 75 degrees. “We weren’t expecting that!”  

She does, however, expect to continue working in the field after graduation. “Being able to work with live animals in the wild was exciting,” said Crane, who’s also a member of the College’s outdoor club, WOODs. “The analysis portion of I.S. has also been really helpful. It’s one thing I didn’t have a lot of practice with, but no matter where I end up working, it will be really important. 

Featured image: Lydia Crane ’25 studied the differences between the gray and black squirrels on campus.

This story originally appeared in the summer 2025 issue of Wooster magazine. 

Posted in Independent Study, Magazine on June 23, 2025.