Mountain Gorillas benefit from social distancing too: Close proximity from tourists affects gorillas sociality

Abstract

Nature-based tourism supports the protection of the mountain gorilla ecosystem, benefiting humans and wildlife populations living therein. Therefore, assessing to what degree the presence and proximity of tourists affect wildlife is important to ensure long-term benefits and to avoid immediate costs, such as the increased risk of pathogen spillover. Because wild and less habituated animals might see human activities as stressors, we hypothesised that the increased presence and proximity of tourists leads to an immediate increase in mountain gorilla social cohesion. To test this hypothesis, we constructed gorilla social networks from association rates before, during and after tourist visits, and when tourists were very close (≤ 3m) or close (> 3m) to them. Our analysis focused on this small distance threshold (≤ 3m and > 3m) because the 7m rule enforced by the national park was violated 85% of the time; the data were therefore heavily unbalanced towards smaller distances. For each network, we calculated metrics that characterized different aspects of social cohesion and we investigated whether and how they differed across conditions. Our analysis showed that gorillas spent more time in closer association after tourists arrived and when they were in very close proximity (< 3m away) to them. Immediate changes were detected in the number of individuals close to each other, the time they spent together and the distance of an individual to all other individuals. At the ultimate level, gorillas might increase social cohesion because they perceive tourists as a risk. At the proximate level, this behaviour might be driven by social buffering. These results highlight the need to enforce the original tourism regulations (i.e., maximum of 8 people per group, including park staff, and keeping a minimum distance of 7m). This will promote human and wildlife wellbeing, while ensuring the continued success of mountain gorilla tourism.