Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal’s parks on his bicycle, on a mission to study squirrels. He covered nearly 200 green spaces from Mirabel to Saint-Bruno, meticulously observing and documenting over 800 grey and black squirrels. What began as a simple task for his undergraduate studies evolved into a personal project to understand how the city’s geography and waterways influence squirrel evolution.
Dinh developed a deep fascination for squirrels during his research, realizing that these creatures are often overlooked as mere pests when they are actually a vital part of the local wildlife. Without access to a car and limited public transport options in suburban areas, he relied on his bike to reach various parks, making him the sole researcher known to manually survey squirrels park by park across the region.
His findings revealed that approximately 12% of Montreal’s squirrels are black on average. Interestingly, as he ventured further north, the percentage of black squirrels increased significantly. In areas just north of Laval, he observed up to 40% of black squirrels, while on the island of Laval, around 20% had black coats. Comparatively, the island of Montreal had approximately 15% black squirrels, and the south shore of Montreal had only 2-3% black squirrels. Dinh, currently pursuing integrative biology at the University of Illinois Urbana-Champaign, attributed these variations to temperature differences, as black squirrels can better absorb heat compared to their grey counterparts.
Moreover, the study highlighted the impact of forest cover on squirrel populations. Areas with denser tree canopies provide a darker backdrop, offering better camouflage for black squirrels. Allison Roth, the study’s senior author and an assistant professor at the University of Missouri, emphasized that the research focused on using squirrels as a model to explore how urban environments drive evolutionary changes.
Roth pointed out that Montreal’s unique geography, segmented by the St. Lawrence River and its tributaries, creates distinct environmental conditions within the city. These fine-scale variations influence genetic and physical adaptations in animal populations, showcasing the intricate relationship between urban landscapes and wildlife evolution.
The study, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” delves into the nuanced changes in wildlife populations on a neighborhood level, challenging the notion that human development alone drives evolutionary shifts in city animals. Urban sprawl, temperature changes, tree cover loss, and natural barriers like riverways all play a role in shaping wildlife populations in urban environments.
The research, part of a special feature by five ecology journals, sheds light on the dynamic interplay between cities and wildlife evolution. For Dinh, this study has transformed his perspective on wildlife, underscoring the resilience of nature in adapting to human-induced modifications.