Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal’s parks on his bicycle, tracking down squirrels. He visited nearly 200 green spaces, from Mirabel to Saint-Bruno, and documented over 800 grey and black squirrels. What began as a student assignment evolved into a personal project to investigate how the city’s layout and waterways influence evolution discreetly.
Expressing his fondness for the creatures, Dinh remarked, “I fell in love with them after observing and contemplating them for a significant period. Squirrels are often overlooked as mere pests, but they are indeed part of the wildlife.” Lack of access to a car and limited public transportation in suburban areas led Dinh to rely on his bike to conduct manual squirrel surveys across the region, making him the sole known researcher to do so.
Dinh’s research revealed that approximately 12% of squirrels in Montreal are black on average. As he ventured further north, the prevalence of black squirrels increased. In areas just beyond Laval, he noted that up to 40% of squirrels had black coats. The percentage decreased to around 20% on the island of Laval, 15% on the island of Montreal, and just 2-3% on the south shore of Montreal. This variation is primarily attributed to temperature, with cooler climates favoring the presence of black squirrels due to their ability to absorb heat better than grey counterparts.
The study, led by senior author Allison Roth from the University of Missouri, aimed to utilize squirrels as a model to examine how urban environments influence evolutionary changes. Roth emphasized the importance of Montreal’s segmented geography, particularly by the St. Lawrence River and its tributaries, in creating distinct environmental settings that drive genetic and physical adaptations in animal populations.
While previous studies compared urban and rural environments broadly, this research delved into neighborhood-specific variations in wildlife. Contrary to the prevailing belief that human development was the main driver of evolutionary changes, the study underscored the multifaceted factors at play, including urban sprawl altering local temperatures, reducing tree cover, and natural barriers posed by riverways.
The findings of the study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” highlight the indirect influence of urbanization on melanism through environmental mediators such as vegetation structure and winter microclimate. Published as part of a special ecological feature, the research underscores the intricate relationship between urbanization and wildlife adaptations.
Reflecting on his research, Dinh acknowledged a shift in his perspective on wildlife, noting, “The dichotomy between city and nature is a misconception. Wildlife continues to thrive despite human modifications to the environment.”