Knowledge Bank

Acoustic, olfactory, and visual predator cues trigger various adaptive responses among a variety of prey species even when they are under human protection since birth. Previous studies have found that domesticated animals show increased vigilance, stress, flight, and aggregation behaviors in response to predation threats. These investigations, however, did not directly test visual threatening cues alone in animals that communicate more with body language than vocalizations while considering individual temperament and social rank. The current study aims to address this issue. Twenty-three horses housed at the OSU Equine Center with mixed age and sex were subjects of this project (mean age = 7 years). The horses were shown predator interactions on a projector without any acoustic cues while their reactions were recorded with an equine heart monitor and camera. Staff ratings on anxiety/fear, social dependency, and rank status in the herd were subsequently collected through care-taker surveys. Results show that domestic horses were able to distinguish an unfamiliar predator from an unfamiliar non-predator based on visual cues alone as measured by physiological stress responses towards the unfamiliar predator stimulus. Young horses were more fearful than the old ones. Male horses showed more physiological stress response to unfamiliar predator cues compared to the females. Social rank was unrelated to fearfulness, social dependency, age, and sex. This project may help elucidate innate vs. learned behaviors that can be expanded to different taxa. Moreover, the results may have important implications for horse-human interactions. Domestic horses are kept for a variety of reasons, including recreation and sports, human comfort and companionship, crowd control, search and rescue operations, breeding, training, and education. The assessments on temperament and fear responses to potentially threatening stimuli have direct relevance to horse welfare and effectively communicating human signals.