Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal’s parks on his bicycle, observing and documenting over 800 grey and black squirrels across nearly 200 green spaces from Mirabel to Saint-Bruno. What began as a simple undergraduate task evolved into a passion project aimed at unraveling how the city’s layout and meandering waterways influence evolution.
Dinh, now studying integrative biology at the University of Illinois Urbana-Champaign, relied on his bicycle to travel extensively due to limited public transit options in suburban areas. This made him the sole researcher known to conduct manual squirrel surveys park by park throughout the region.
His research revealed that approximately 12% of squirrels in Montreal are black, with higher percentages found in northern regions. In areas just north of Laval, up to 40% of squirrels displayed black coloration, while on the island of Laval, around 20% were black. On the island of Montreal, the figure stood at approximately 15%, dropping to just two or three percent on the south shore.
The study attributed these variations primarily to temperature differences. The cooler climates in northern areas favor black squirrels due to their better heat absorption capabilities compared to grey squirrels. Additionally, the presence of denser forest cover provides a darker backdrop, enhancing the camouflage of black squirrels.
Senior author Allison Roth, 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 distinct urban layout, characterized by diverse neighborhoods and varying tree cover levels, creates fine-scale environmental differences that can lead to genetic and physical adaptations within the same animal population.
While traditional studies tended to compare wildlife changes between cities and rural areas, this research delves into neighborhood-specific variations. It highlights that urbanization, while influential, is just one piece of the complex puzzle shaping wildlife adaptations. The study underscores the indirect impact of urban sprawl on melanism in squirrels through altering local vegetation structures and microclimates.
Published as part of a special feature by ecology journals, this research showcases the importance of data and collaboration in addressing significant ecological questions. Dinh reflects on how his perspective on wildlife has shifted, recognizing the coexistence of city and nature and the resilience of wildlife amidst human modifications.