Observations on Anti-Predator Defense Behavior in Feral Horses in Venezuela.

Apart from vigilance and flight, anti-predator defense behavior in horses has not been well documented despite its importance during natural selection. In this study, observations of a feral herd (around 140) of Venezuelan horses sympatric with puma and jaguar divided such defense into precaution and reaction. Group living and the avoidance of danger areas are precautionary measures enhanced by the stallion's vigilance and his actions to keep small foals with the band. Reactions to perceived threats comprise communication of alarm; bunching, or cohesion, as a primary response; massed flight following self-organizing principles; and reassembly of bands. Stallions usually initiated this behavioral process. Stallions' initial reactions to perceived threats were "investigation", "move away", "run away", and "stampede", and resulting herd behavior was categorized into 27 responses. Data analysis through Observation Oriented Modeling indicated that each category of initial stallion response to perceived threats was associated with a recurring pattern of subsequent herd behavior. Prominent behaviors enhanced cohesion and synchrony, as well as velocity and direction matching. A fourth observed category was the cohesive "run to band" of a startled outlying member, in which the individual's alarm might transmit to the band or the band's calm transmit to the individual. The results emphasize the importance of communication, social cohesion, and synchronous action in times of perceived threats, their continuous practice during maintenance activities, and the social needs and understanding management of domestic horses.