A wild squirrel thriving in the city

Despite an urban environment that isn’t always suitable, many animals still choose to settle there. While the Eurasian red squirrel has made the city its new home, not all species cope equally well with the disruptions of urban life. Some rodents, when pushed to their limits, see their problem-solving abilities increase, while others are unable to cope. A better understanding of the dynamics of these interactions could help reduce conflicts between humans and animals in cities.   Unlike the natural environment, urban areas are covered in concrete and man-made structures and teem with people and vehicles. Despite this inhospitable environment, some wild species choose to migrate to urban areas and thrive there. Animals often demonstrate adaptability and behavioral agility to cope with the challenges and demands of city life. Compared to their rural counterparts, urban wildlife displays great flexibility and an extraordinary ability to solve problems, allowing them to exploit new resources and demonstrate strong resilience in the face of human-altered environmental conditions. This is the case with the Eurasian red squirrel (Sciurus vulgaris). Researchers led by Itsuro Koizumi of Hokkaido University sought to identify the specific characteristics of urban environments responsible for the development of these city-dwelling animals’ performance and their relative importance. They assessed the impact of four urban environmental characteristics—direct human disturbance, indirect human disturbance, the presence of greenery, and squirrel population size—on the rodents’ ability to solve a problem related to city life. A puzzle involving nuts, levers, and counterintuitive solutions—with a treat as a reward—was set up in eleven urban areas in Hokkaido, Japan, selected for their diversity in terms of human or animal density, and the presence of buildings or green space. Of the 71 squirrels faced with these unusual puzzles, just over half succeeded (53.5%). However, an increase in human population, the number of buildings, or proximity to other squirrels reduces the chances of success. But when a squirrel succeeds under these challenging conditions, the time it takes to reach the treat decreases with each attempt, particularly in the most densely populated areas. “One of the main stressors—direct human disturbance—causes some squirrels to fail and others to succeed better at solving novel problems,” notes Pizza Ka Yee Chow, the article’s lead author. One proposed explanation is that squirrels living in urban areas always perceive residents as a potential threat but react to it differently. Some succeed by quickly implementing a solution, while others simply give up—in both cases to avoid proximity to humans. ” These results show that the urban environment shapes two extreme phenotypes in terms of behavioral adaptability. The first promotes more effective learning under stress, while the other, conversely, causes animals to give up when faced with new challenges. A better understanding of these two opposing dynamics could help reduce conflicts between animal and human populations in urban environments and improve wildlife management in cities.