Human disturbance has a significant impact on the behaviour and habitat use of urban wildlife, however, in some situations urban grey squirrels may actually feel safer from predators where our activity is high.
A new study from the University of Exeter, published in Oikos, reveals the paradoxical ways grey squirrels balance risk and foraging in urban environments. Researchers measured how much food squirrels left behind in standardised food patches in different places, which reflects how dangerous they perceived their local surroundings to be. They found that squirrels felt safer from predators near roads when noise levels were consistently loud.
However, squirrels also perceived foraging as more dangerous where noise was less consistent. The findings highlight the complex trade-offs squirrels face in urban environments when balancing the risks and benefits associated with living alongside humans.
Dr Sasha Dall from the University of Exeter said: "Our findings suggest human activities have a double-edged impact on urban wildlife like the grey squirrel. While human disturbance can offer reduced risk from predators in some situations, it can also increase it in others. Squirrels are having to adapt to these challenges by altering their foraging behaviour and habitat use.
"We now need to explore the variations in food supply, reproductive success, and survival rates of grey squirrels across different levels of urbanisation to better understanding the impact human disturbance has on them."
The research shows how urban features can reshape the 'landscape of fear' in urban wildlife and that not all human disturbance is equal. Researchers offered squirrels the choice between 'safe' (under cover) and 'risky' (out in the open) artificial feeding patches and found that the difference in food eaten from safe and risky foraging patches decreased closer to roads, particularly where noise was loud but steady. This suggests squirrels perceive these sites as lower in predation risk.
Dr Kristin Thompson, who conducted this research as part of her PhD at the University of Exeter, said: "These results seem counterintuitive, but show whilst roads can present a risk of being hit by a vehicle, squirrels living near roads appear to perceive the risk of being caught by a predator as lower, if road noise is consistent. This ability to navigate complex risks is an example of why grey squirrels are so successful in urban spaces."
Dr Sasha Dall was funded by a Royal Society Leverhulme Trust Senior Research Fellowship.
