Francis Quang-Hai Dinh embarked on a unique project during his initial summer at McGill University, scouring Montreal’s parks on his bicycle in search of squirrels. Venturing to around 200 green areas spanning from Mirabel to Saint-Bruno, he meticulously observed and documented over 800 grey and black squirrels. What began as a simple undergraduate assignment evolved into a personal endeavor to investigate how the city’s landscape and meandering water systems influence evolution surreptitiously.
Dinh’s fascination with squirrels blossomed as he dedicated substantial time to observing and contemplating these creatures. Despite squirrels often being viewed as mere nuisances rather than wildlife, Dinh’s perspective shifted as he delved deeper into his research. Operating without a car and facing limited public transportation options in suburban locales, he heavily relied on his bicycle to conduct extensive surveys, making him the sole researcher known to manually scrutinize squirrels park by park throughout the region.
In his findings, Dinh discovered that approximately 12% of Montreal’s squirrel population exhibited black coloration. Notably, as he ventured further north, the prevalence of black squirrels increased significantly. In bordering regions just north of Laval, he observed up to 40% of squirrels with black fur, while on the island of Laval, the figure stood at around 20%. Comparatively, on the island of Montreal and the southern shore, the percentage dwindled to 15% and 2-3%, respectively. Dinh, currently pursuing integrative biology at the University of Illinois Urbana-Champaign, attributed these variations primarily to temperature, with black squirrels benefiting from superior heat absorption due to their coloration.
Moreover, the study identified forest cover as another influential factor, with denser tree canopies providing a darker backdrop that enhances 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 transcends squirrels themselves, serving as a model to assess how urban environments catalyze evolutionary shifts.
Roth highlighted the unique environmental nuances of cities like Montreal, characterized by diverse neighborhoods, varying tree coverage, and natural boundaries such as waterways that foster micro-environmental divergences. She underscored Montreal’s segmentation by the St. Lawrence River and its tributaries, creating distinct habitats that shape evolutionary processes among squirrel populations.
The study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” represents a departure from previous research that compared city and rural wildlife dynamics on a broader scale. Contrary to the conventional belief that human development solely drives evolutionary changes in urban settings, the study elucidates that cities constitute one facet of a multifaceted puzzle. Urban expansion alters local temperatures, reduces tree cover, and establishes natural barriers like river networks, indirectly influencing the prevalence of melanistic traits among squirrels.
Published as part of a special feature by several ecology journals, the research underscores the significance of data-driven collaboration in unraveling complex ecological inquiries. Reflecting on his experience, Dinh noted a profound shift in his perspective on wildlife, emphasizing the coexistence of urban environments and natural habitats. He stressed the resilience of wildlife amid human interventions, highlighting the enduring presence of fauna despite the modifications imposed by urbanization.
Through his meticulous observations and dedicated research, Dinh has not only expanded our understanding of squirrel populations but also shed light on the intricate interplay between urban environments and evolutionary adaptations in wildlife.