Human activity influences wildlife populations and activity patterns: implications for spatial and temporal refuges

Human activity affects plant and animal populations across local to global scales, and the management of recreation areas often aims to reduce such impacts. Specifically, by understanding patterns of human activity and its influence on animal populations, parks and recreation areas can be managed to provide spatial and temporal refuge to wildlife most sensitive to this type of human disturbance. However, additional research is necessary to understand how human activity influences wildlife populations, habitat use, and activity patterns for a diversity of wildlife species. We studied the potential impacts of human activity (as measured by nonmotorized recreationists) on populations and activity patterns of 12 mammal species, including herbivores and carnivores, from 63 motion-activated cameras that sampled game trails and human trails with varying degrees of human activity along the Front Range of Colorado. Human activity was greatest during the day and minimal or absent during the night. All wildlife species in our study used human trails, although the extent to which human recreation altered the occupancy, relative habitat use, and activity patterns of wildlife varied across species, where some animals appeared to be more influenced by human activity than others. Some species (e.g., fox squirrel, red fox, and striped skunk) did not demonstrate a response to human activity. Other species (e.g., black bear, coyote, and mule deer) altered their activity patterns on recreation trails to be more active at night. Across all wildlife, the degree to which animals altered activity patterns on human trails was related to their natural activity patterns and how active they were during the day when human activity was greatest; species that exhibited greater overlap in natural activity patterns with humans demonstrated the greatest shifts in their activity, often exhibiting increased nocturnal activity. Further, some species (e.g., Abert's squirrel, bobcat, and mountain lion) exhibited reduced occupancy and/or habitat use in response to human recreation. Managing spatial and temporal refuges for wildlife would likely reduce the impacts of human recreation on animals that use habitat in proximity to trail networks.