Behavioral responses of black bears to human presence and infrastructure in Yosemite National Park

Abstract

Human disturbance is a pervasive force shaping wildlife movement and behavior across spatial and temporal scales. Even in protected areas, recreation-related human presence and infrastructure can impose distinct and overlapping effects that are important to disentangle for managing human–wildlife interactions. California's Yosemite National Park has experienced a long history of human–black bear (Ursus americanus) interactions, particularly where high-quality habitat overlaps with recreation. A 3-month park closure at the start of the COVID-19 pandemic in 2020 provided a rare opportunity to investigate bear responses to infrastructure with and without human presence. Using global positioning system (GPS) collar data from 30 black bears (2014–2022), we evaluated behavioral responses across multiple scales, including home range size, habitat selection, behavioral state, and diel activity, during periods of normal visitation and closure. Under normal visitation, development strongly influenced all bear behaviors and was associated with larger home ranges, higher movement probabilities, and more nocturnal activity. During the closure, bears exhibited shifts in their fine-scale behaviors while broad-scale space use remained unchanged. Bears increased selection for development within their home ranges, became more diurnal, and moved more, with the strongest behavioral shifts occurring in the most developed areas. Our findings indicate that bears maintain use of resource-rich areas near development while modifying their fine-scale behaviors to avoid direct human encounters. By assessing how human presence and infrastructure shape bear behavior at multiple scales, this study provides guidance for managing human activities and bear behavior to support human–bear coexistence.