Behavioural adaptability of wild geladas (Theropithecus gelada) in human-impacted areas revealed by encounters with free-roaming dogs and potential threats

Studying interactions between domestic species and wild primates is crucial for understanding the impacts of human expansion on wildlife. While free-roaming domestic dogs are one of the most common human-introduced carnivores and pose potential threats to primates, their direct influence on primate behaviour remains largely overlooked. Geladas (Theropithecus gelada), a primate species endemic to Ethiopia's Afro-alpine grasslands with a specialized diet, are facing challenges from habitat loss and interactions with domestic animals throughout their geographical range. Here, we followed 17 gelada group units in an unprotected area of Ethiopia (6-month period, 598 h of observation) and explored their behavioural responses to different natural and human-related threats. We observed strong vigilance in response to the presence of humans chasing nearby groups, as well as in response to dogs and eagles. Other raptors and birds of prey (including vultures and kites) produced no vigilance response, or only a modest one (e.g., augur buzzard). We also report encounters and interactions (n = 16) between dogs and geladas. Although we observed some behaviours associated with agonism and anxiety from both sides, the presence of dogs at close proximity was mainly tolerated. This contrasts with data from populations inhabiting protected areas where geladas typically exhibit flight responses to encounters with dogs. These differences between populations hint at gelada behavioural plasticity to adapt and live in human-impacted environments with limited alternative feeding sites. Increased awareness and documentation of dog-primate interactive events are essential to better grasp the broader implications of human-wildlife coexistence, one of the most important challenges of the Anthropocene.