Reserves as double-edged sword: Avoidance behavior in an urban-adjacent wildland

Abstract

Human activities affect wildlife in a variety of direct (e.g., hunting, supplemental feeding, and culling) and indirect (e.g., displacement from habitat loss, competition with introduced invasive species, and avoidance of human-dominated landscapes) ways. Even ostensibly benign activities such as hiking or horseback riding in established parks may affect the spatial and temporal activity patterns of wildlife species. Characterization and quantification of effects is essential if parks and other protected areas are to balance the dual needs to nurture an appreciation of wildlands or satisfy a need to encounter nature (sensu the biophilia hypotheses) and to ensure that wild animals can survive and reproduce. We explored how human presence affects wildlife presence in a spatially extensive system of camera traps established in various protected areas in coastal southern California. To characterize and quantify effects we developed a conceptual framework on the basis of joint probabilities of occurrence on a per-camera basis and created a novel statistical approach to assess whether observed probabilities of co-occurrence differed from expected probabilities of co-occurrence. We found that same-day co-occurrence of wildlife and humans was significantly lower than expected at >90% of the cameras established. This pattern held across sites, across the seven species of large and medium-sized mammals (Bobcat Lynx rufus, Mountain Lion Puma concolor, Gray Fox Urocyon cinereoargenteus, Coyote Canis latrans, Striped Skunk Mephitis mephitis, Northern Raccoon Procyon lotor, and Mule Deer Odocoileis hemionus), and across the five types of human disturbance examined (hikers, bicyclists, domestic dogs, vehicles, and equestrians). Our results demonstrate that human presence acutely affects same-day wildlife detections in protected areas, supporting the hypothesis that avoidance behaviour is a type of “mortality-free predation.” Adaptive and flexible management plans need to be established, evaluated, and updated regularly to facilitate the human nature experience while lessening as much as possible long-term degradation of wildlife habitat. Wildlife in urban-adjacent preserves constitute a major part of the nature experience by humans and require effective management of pressures for use and recreation along aside those for wildlife habitat needs.