Francis Quang-Hai Dinh embarked on a unique summer project during his first year at McGill University, exploring Montreal’s parks on his bicycle in search of squirrels. He meticulously observed and documented over 800 grey and black squirrels across nearly 200 green spaces spanning from Mirabel to Saint-Bruno.
What began as a simple undergraduate assignment evolved into a personal mission to understand how the city’s geography and waterways influence the evolution of its wildlife. Dinh developed a deep fascination for squirrels, realizing that these creatures, often viewed as pests, are an integral part of the urban ecosystem.
Despite the challenges of limited public transportation in suburban areas, Dinh relied on his bicycle to conduct the first known manual squirrel survey park-by-park throughout the region.
His research revealed interesting patterns regarding the prevalence of black squirrels in different parts of Montreal. While approximately 12% of squirrels in the city are black on average, the percentage increases as one moves further north. In areas just north of Laval, Dinh found that up to 40% of squirrels had black coats, while on the island of Laval, around 20% were black. Comparatively, on the island of Montreal, the figure was approximately 15%, and on the south shore, it dropped to just two or three percent.
The study identified temperature as a key factor influencing the distribution of black squirrels, with cooler northern regions providing a more favorable environment for these animals due to their ability to absorb heat better with their dark coloration. Additionally, the density of forest cover played a role, as black squirrels are better camouflaged in areas with a denser tree canopy.
Allison Roth, the senior author of the study and an assistant professor at the University of Missouri, emphasized that the research focused not only on squirrels but also on using them as a model to study how urban environments drive evolutionary changes. Montreal’s unique landscape, characterized by diverse neighborhoods and distinct natural boundaries like the St. Lawrence River, creates fine-scale environmental variations that can lead to genetic and physical adaptations within the same animal population.
The study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” breaks new ground by examining changes in wildlife on a neighborhood-by-neighborhood basis, challenging the notion that human development is the sole driver of evolutionary changes in urban settings. It underscores the intricate relationship between urbanization, local vegetation structure, winter microclimate, and wildlife adaptations.
As for Dinh, his experience studying squirrels has transformed his perspective on wildlife and urban ecosystems. He reflects on the coexistence of nature and the city, recognizing that wildlife will persist and adapt despite human modifications to the environment.
