Human presence and human footprint have non-equivalent effects on wildlife spatiotemporal habitat use

Abstract

Human impacts on wildlife stem from both our footprint on the landscape and the presence of people in wildlife habitat. Each may influence wildlife at very different spatial and temporal scales, yet efforts to disentangle these two classes of anthropogenic disturbance in their effects on wildlife have remained limited, as have efforts to predict the spatial extent of human presence and its impacts independently of human footprint. We used camera trap data from a 1400-km2 grid spanning wildlands and residential development in central California to compare the effects of human presence (human detections on camera) and footprint (building density) on mammalian predators. We then developed a model predicting the spatial extent of human presence and its impacts across the broader landscape. Occupancy modeling and temporal activity analyses showed that human presence and footprint had non-equivalent and often opposing effects on wildlife. Larger predators (pumas Puma concolor, bobcats Lynx rufus, coyotes Canis latrans) were less active where human footprint was high but avoided high human presence temporally rather than spatially. Smaller predators (striped skunks Mephitis mephitis, Virginia opossums Didelphis virginiana) preferred developed areas but exhibited reduced activity where human presence was high. A spatial model, based on readily available landscape covariates (parking lots, trails, topography), performed well in predicting human activity outside of developed areas, and revealed high human presence even in remote protected areas that provide otherwise intact wildlife habitat. This work highlights the need to integrate multiple disturbance types when evaluating the impacts of anthropogenic activity on wildlife.