Flexible changes in mountain gorilla (Gorilla beringei beringei) ranging patterns in response to snare encounters

Human activities, including hunting within protected areas, are reshaping the spatiotemporal behavior of wildlife by creating anthropogenic landscapes of fear. In nonhuman primates, these landscapes can drive flexible alterations in movement that reflect adaptive responses to perceived risks. However, given the rapid pace of anthropogenic change, it remains unclear whether behavioral flexibility is adequate for survival. Mountain gorillas (Gorilla beringei beringei) in Volcanoes National Park, Rwanda, are vulnerable to entrapment in snares set by human communities hunting other species to sustain their livelihoods. In this study, we investigated how the ranging behavior of eight gorilla groups changed in response to snare encounters, using GPS data collected between 2009 and 2024 to estimate site fidelity and revisit frequency, and data from 2023 to 2024 to calculate daily travel distances (DTDs). We applied generalized linear mixed models and Wilcoxon signed-rank tests to compare each measure of space-use following encounters to baseline values. We found that snare encounters significantly influenced ranging patterns, with DTDs increasing by 55 % and site fidelity decreasing by 22 % following these events. Additionally, groups revisited encounter sites less frequently. These results demonstrate that gorillas have the capacity to flexibly alter ranging behavior to avoid the immediate risks associated with snare encounters. However, these encounters may have cascading negative effects on their fitness and survival. To mitigate the impacts of illegal activities, conservation efforts must also be flexible and monitor the effects of anthropogenic stressors on mountain gorillas while also addressing the underlying needs of communities adjacent to protected areas.