Francis Quang-Hai Dinh’s initial summer at McGill University was dedicated to exploring Montreal’s parks on his bicycle in search of squirrels. He meticulously documented over 800 grey and black squirrels in nearly 200 green spaces spanning from Mirabel to Saint-Bruno. What began as a university task evolved into a personal quest to unravel how the city’s layout and intricate waterways influence evolution discreetly.
Expressing his admiration for squirrels after extensive observation, Dinh remarked, “We often overlook squirrels as mere pests rather than recognizing them as wildlife.” Due to limited public transportation in suburban regions and his lack of a car, Dinh extensively relied on his bicycle to reach distant locations, making him the sole known researcher to manually conduct squirrel surveys park by park throughout the area.
The investigation revealed that approximately 12% of Montreal’s squirrels are black on average. As Dinh ventured further north, he discovered a higher prevalence of black squirrels. In locales just beyond Laval, up to 40% of squirrels exhibited black fur, distinguishing them from the common grey variety. The percentage of black squirrels decreased progressively from the island of Laval (20%), the island of Montreal (around 15%), to the southern shore of Montreal (2-3%).
Several factors contribute to the prevalence of black squirrels, with temperature being the primary driver. The cooler climates further north favor the black coloration of squirrels as it absorbs heat more effectively than grey coats. Additionally, the density of forest cover plays a role, with a denser tree canopy providing a darker backdrop that aids in the camouflage of black squirrels.
Allison Roth, the study’s senior author and a University of Missouri assistant professor, emphasized that the research focuses on using squirrels as a model to explore how urban settings induce evolutionary adaptations. Cities like Montreal, with diverse neighborhoods and distinct environmental features such as waterways, offer microscale variations that can lead to genetic and physical changes within animal populations.
The study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” delves into the intricate evolutionary dynamics observed in Montreal’s squirrel population. Unlike previous studies that generalized urban-rural comparisons, this research delves into the nuanced changes occurring at a neighborhood level. Urbanization, while impacting local temperatures and vegetation, serves as just one piece of the puzzle influencing wildlife adaptations.
Dinh, reflecting on his experience, shared that his perspective on wildlife has been permanently altered. He highlighted the coexistence of wildlife within urban landscapes, emphasizing that nature persists despite human interventions.
