New insights into urban life's impact on squirrels' cognitive abilities

The impact of the urban environment on squirrels' problem-solving, learning and memory has been highlighted in new research from the UK's University of Chester and Hokkaido University in Japan.

In one of the few studies that joins ecology and psychology to look at the animal mind in the wild, researchers have examined how stressful urban environmental characteristics are for squirrels and discovered they have a greater effect on cognitive performance than previously shown.

The research, "Ripple effects of urban environmental characteristics on cognitive performance in Eurasian red squirrels," is published in the Journal of Animal Ecology.

They explored how much urban areas—with their buildings, traffic, less greenery, and, most prominently, more humans—cause a disturbance to squirrels by setting them challenges testing their cognitive skills—how they acquire, store and use information to react to the environment.

The team observed Eurasian red squirrels—a species that thrives in urban environments—in 11 urban areas in Obihiro, Japan, and the impact of: direct human disturbance—measured by the average number of humans present per day; indirect human disturbance—the number of buildings; squirrel population size and extent of green coverage.

The research built on a previous study which found that some of these characteristics of the urban environment affect squirrels' ability to solve problems, with them either not solving problems at all or showing an enhanced ability to find the solution.

In this study, they wanted to discover if there was a 'ripple effect' beyond problem-solving performance by exploring if urban settings would also affect other related cognitive traits such as generalization—the ability to solve a similar but different problem—or memory—the ability to recall the same information after an extended period of time.

A total of 38 red squirrels who had previously solved a novel problem—extracting food from a transparent box by pushing and pulling levers—the 'innovators' of the original task—were studied to see if they could solve a similar problem and also recall the solution after time.

The researchers found that urban characteristics, in many cases, affected squirrels' performance in the generalization and memory tasks at both population and individual levels—either decreasing or increasing performance, depending on the combination of characteristics.

For example, increased direct and indirect human disturbance, led to less success in the generalization or memory task at the population level. Increased direct human disturbance and less green coverage resulted in quicker problem solving at individual levels.

Dr. Pizza Ka Yee Chow, Lead Researcher and Lecturer in the School of Psychology at the University of Chester outlined that a possible explanation for this could be how squirrels perceive humans, and likely their dogs, as a threat.

She said, "Such a threat is often unpredictable and may cause frequent interruptions when they are solving the task, causing some squirrels to give up and forage elsewhere or others to quickly solve the task and retreat to a tree for safety or to minimize their exposure to threats."

Discussing the wider study, she added, "Despite investigations into the effect of urban environments on aspects such as wildlife physiology and behavior, the relationship between urban environments and wildlife cognition has remained largely unclear.

"However, such research is needed as urban areas expand, leading to more species living in these environments, to discover more about how its wildlife thrives or declines, and to inform city management of green space and land use such as creating larger 'buffer' zones for wildlife, to decrease disturbance."

She continued, "Our results partially support the ripple effect hypothesis, suggesting that urban environmental characteristics are stressors for squirrels and have a greater impact on shaping cognitive performance than previously shown.

"Together, these results provide a better understanding of traits that support wildlife in adapting to urban environments, which we can further build on by examining different species and other cognitive performance."