Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal parks on his bicycle, observing and documenting over 800 grey and black squirrels in nearly 200 green spaces from Mirabel to Saint-Bruno. What began as a simple undergraduate task evolved into a personal project to investigate how the city’s layout and waterways influence evolution.
Dinh, who is now studying integrative biology at the University of Illinois Urbana-Champaign, relied on his bike due to limited public transit options in suburban areas, becoming the sole researcher to conduct manual squirrel surveys park-to-park across the region.
His research revealed that while approximately 12% of Montreal’s squirrels are black on average, the percentage of black squirrels increased as he traveled further north. In areas just north of Laval, up to 40% of squirrels were black, compared to around 20% on the island of Laval, 15% on the island of Montreal, and just 2-3% on the south shore of Montreal.
The study identified temperature as the primary factor influencing the prevalence of black squirrels, with cooler climates in the north favoring their black coloration due to better heat absorption. Additionally, forest cover played a role, as denser tree canopies provided a darker background, enhancing the camouflage of black squirrels.
Allison Roth, the study’s senior author and an assistant professor at the University of Missouri, emphasized that the research focuses on using squirrels as a model to explore how urban environments drive evolutionary changes. Montreal’s segmented layout, defined by the St. Lawrence River and its tributaries, creates distinct environmental variations that can lead to genetic and physical adaptations within the squirrel population.
The study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” deviates from previous research by examining wildlife changes on a neighborhood-specific level, highlighting the intricate interplay between human development, local temperature changes, tree cover reductions, and natural barriers created by riverways.
Ultimately, the study suggests that urbanization indirectly influences squirrel melanism through environmental factors such as vegetation structure and winter microclimate. The research is part of a special feature by five ecology journals focusing on collaborative efforts to address significant ecological inquiries.
Dinh reflected on his transformed perspective, noting that wildlife coexists with urban development despite the perception of nature and the city as separate entities. He emphasized the resilience of wildlife in adapting to human modifications.