Francis Quang-Hai Dinh embarked on a unique summer adventure during his first year at McGill University, spending his days cycling through various parks in Montreal in search of squirrels. His mission led him to observe and document over 800 grey and black squirrels in almost 200 green spaces spanning from Mirabel to Saint-Bruno.
Initially an undergraduate assignment, Dinh’s project evolved into a personal fascination with uncovering how the city’s layout and meandering waterways influence evolution subtly. He expressed his growing admiration for squirrels, emphasizing that they are often overlooked as mere pests when, in fact, they are part of the city’s wildlife ecosystem.
Dinh, lacking a car and facing limited public transportation options in suburban regions, relied on his bicycle to conduct his extensive squirrel surveys, becoming the sole researcher known to manually study squirrels park by park across the area.
His findings revealed that approximately 12% of squirrels in Montreal are black on average. As he ventured further north, this percentage increased significantly. In locations just beyond Laval, he encountered up to 40% of black squirrels, while on the island of Laval, roughly 20% showcased this darker coat color. Comparatively, on the island of Montreal, the proportion was around 15%, dropping to only two to three percent on the south shore of Montreal.
The study attributed the prevalence of black squirrels to multiple factors, with temperature playing a crucial role. The cooler climate in northern areas favors black squirrels due to their enhanced heat absorption capabilities compared to grey squirrels. Additionally, the density of forest cover influences the squirrel populations, as black squirrels blend better in darker surroundings created by a denser tree canopy.
Allison Roth, the senior author of the study and an assistant professor at the University of Missouri, highlighted that the research focuses on using squirrels as a model to examine how urban environments drive evolutionary changes. Montreal’s diverse neighborhoods, varying tree cover levels, and natural boundaries, such as its waterways, create micro-environmental variations that can lead to genetic and physical adaptations within the same species.
Roth emphasized the significance of Montreal’s segmented structure, with the St. Lawrence River and its tributaries creating distinct habitats akin to isolated islands. This spatial arrangement influences squirrel populations and showcases how evolution can unfold in response to environmental conditions.
The research, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” breaks new ground by analyzing wildlife changes on a neighborhood-specific basis rather than comparing urban and rural settings broadly. It underscores that urbanization, local vegetation structures, and winter microclimates play pivotal roles in shaping melanism in squirrels, challenging previous assumptions about the main drivers of evolutionary changes.
Dinh, reflecting on his experience, remarked that his perspective on wildlife had shifted irreversibly. He emphasized the coexistence of urban development and natural habitats, emphasizing the resilience of wildlife in adapting to human-made modifications.
The study’s publication is part of a special feature by ecological journals, highlighting collaborative efforts and data-driven approaches to address significant ecological inquiries.
