Ortiz-Jimenez Chelsea A, Conroy Sophie Z, Person Erin S, DeCuir Jasper, Gall Gabriella E C, Sih Andrew, Smith Jennifer E
Department of Environmental Science and Policy, University of California, Davis, California, USA.
Department of Biology, Mills College at Northeastern University, Oakland, California, USA.
Ecology. 2025 Jan;106(1):e4499. doi: 10.1002/ecy.4499.
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 investigate 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-19 pandemic (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 foraging that reflected 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 among human and dog activity, natural predators, and microhabitat features. Our findings elucidate the myriad ways humans directly and indirectly influence animal perception of safety and danger.
人类可能在为小型猎物哺乳动物提供躲避捕食者的时空庇护方面发挥关键作用,但很少有研究捕捉到这些影响在空间和时间上的异质性。全球新冠疫情封锁限制提供了一个独特的机会,来研究半城市公园中人类存在的突然变化如何影响野生动物。在这里,我们量化了人类和自然捕食者空间分布的变化如何在新冠疫情年(2020年)和非新冠年(2019年)影响加州地松鼠(Otospermophilus beecheyi)的恐惧景观。我们使用结构方程建模方法来探索人类存在、捕食者存在和栖息地特征对觅食的直接和间接影响,这些影响反映了恐惧反应(例如,放弃密度[GUDs]、觅食者数量以及在食物斑块处的平均食物摄入率)。2019年,人类和狗对GUDs有中等影响;松鼠在人类和狗经常光顾的区域恐惧程度较低(GUDs较低),但猛禽的影响较弱。相比之下,2020年,人类和狗对GUDs的影响较弱;松鼠更害怕猛禽的高活动量、开阔天空和地面覆盖物。在这两年中,离避难所最远的松鼠最规避风险。总体而言,我们的分析表明,2020年与人类存在浓度变化相关的自然捕食者感知风险增加。因此,风险敏感型觅食在空间和时间上是动态的,取决于人类和狗的活动、自然捕食者和微栖息地特征之间的复杂相互作用。我们的研究结果阐明了人类直接和间接影响动物对安全和危险感知的多种方式。