Human presence shifts the landscape of fear for a free-living mammal

Abstract

Humans may play a key role in providing small prey mammals spatial and temporal refuge from predators, but few studies have captured the heterogeneity of these effects across space and time. Global COVID-19 lockdown restrictions offered a unique opportunity to explore how a sudden change in human presence in a semi-urban park impacted wildlife. Here we quantify how changes in the spatial distributions of humans and natural predators influenced the landscape of fear for the California ground squirrel (Otospermophilus beecheyi) in a COVID (2020) and non-COVID (2019) year. We used a structural equation modeling approach to explore the direct and indirect effects of human presence, predator presence, and habitat features on fear responses [e.g., giving-up densities (GUDs), number of foragers, and average food intake rate while at food patches]. In 2019, humans and dogs had moderate effects on GUDs; squirrels were less fearful (lower GUDs) in areas frequently visited by humans and dogs, but the effects of raptors were weak. In contrast, in 2020, the effects of humans and dogs on GUDs were weak; squirrels were more fearful of high raptor activity, open sky, and ground cover. In both years, squirrels farthest from refuge were the most risk-averse. Overall, our analyses revealed an increase in perceived risk from natural predators in 2020, associated with a change in the concentration of human presence. Thus, risk-sensitive foraging was dynamic across space and time, depending on a complex interplay between human, dog, and natural predator activity, and microhabitat features. Our findings elucidate the myriad ways humans, directly and indirectly, influence animal perception of safety and danger.