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 across nearly 200 green spaces from Mirabel to Saint-Bruno. What initially began as an undergraduate assignment evolved into a personal project to investigate how the city’s layout and waterways influence evolution.
Dinh, who is now pursuing integrative biology at the University of Illinois Urbana-Champaign, conducted manual squirrel surveys park-by-park, relying on his bicycle due to limited public transportation options in suburban areas.
His research revealed that approximately 12% of squirrels in Montreal are black, with higher concentrations of black squirrels found as he traveled further north. In regions just north of Laval, up to 40% of squirrels were black, while on the island of Laval, about 20% were black, and on the island of Montreal, around 15%. This percentage dropped to 2-3% on the south shore of Montreal. The study attributed this distribution to temperature variations, with cooler climates favoring black squirrels due to their better heat absorption.
Additionally, the study highlighted the role of forest cover in squirrel coloration, noting that denser tree canopies provide a darker backdrop where black squirrels are more effectively camouflaged.
The senior author of the study, Allison Roth, emphasized that urban environments like Montreal offer diverse neighborhood settings, tree cover levels, and natural boundaries that create nuanced environmental conditions influencing genetic and physical adaptations in animal populations. The study aims to use squirrels as a model to explore how urban landscapes drive evolutionary changes.
The research, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” examines wildlife adaptations at a neighborhood level within cities, challenging the notion that human development is the sole driver of evolutionary changes in urban wildlife. It suggests that urbanization indirectly impacts melanism through environmental factors like vegetation structure and winter microclimate.
By investigating these ecological questions, the study contributes to a special feature by five ecology journals focusing on data-driven research and collaboration. Dinh reflected on his changed perspective on wildlife, emphasizing the coexistence of city life and nature and the resilience of wildlife despite human modifications to the environment.