The impact of tourist visits on mountain gorilla behavior in Uganda: proximity to tourists and risk of extinction

Abstract

Tourism can play a significant role in the conservation of mountain gorillas (Gorilla beringei beringei) by financing the protection of their habitat, but few systematic studies have focused on the impacts of tourist presence on gorilla behavior. We assessed stress-coping mechanisms (prosocial behaviors), behavioral indicators of stress (self-scratching), direct interactions with humans (agonistic, neutral and avoidance behaviors), and changes in social cohesion patterns (time spent with and number of individuals in close association), in the presence and absence of tourist groups visiting one group of mountain gorillas living in Bwindi Impenetrable National Park, Uganda. Generalized linear mixed models and social network analysis were used to analyse differences in gorilla behavior as a function of (a) presence vs. absence of tourists and (b) proximity to tourists (<3 m vs >3 m). Contrary to guidelines, tourists spent 60% of their viewing time within 3 m of the gorillas. During tourist visits, gorillas increased time spent in prosocial behavior and rates of self-scratching and human-directed behavior, increasing also social cohesion. When tourists approached gorillas within 3 m, prosocial behavior, human-directed behavior, and social cohesion increased, but only adult males increased self-scratching rates. We conclude that tourists are influencing gorilla behavior and we recommend following and enforcing the IUCN guidelines by keeping a minimum 7 m distance when viewing gorillas.