Help horses help themselves – A literature review on social relationships in the context of anti-predator behaviour

Due to the reappearance of wolves in human-dominated landscapes, interactions between predators and livestock, including horses, have become a common occurrence, posing challenges for the protection of livestock. Little research exists on horse-wolf interactions and anti-predator responses by horses, and field studies under natural conditions on the reactions of horses towards wolves are lacking. Natural group dynamics and collective behaviour in horses are crucial, as these factors can influence the ability to avoid or alleviate attacks by wolves and thus help minimise horse-wolf conflict. This paper reviews the existing literature on interaction and collective behaviour in horse groups, focusing on social bond formation, group cohesion and synchronisation in explaining group dynamics. The paper also presents a literature overview on defensive behaviour and anti-predator responses by domesticated and feral horses. We discuss the findings on interaction and collective behaviour and its influence on anti-predator responses. The literature suggests grouping and gathering of foals, kicks and chasing as well as cohesion and synchronised fleeing and collision avoidance as effective defence behaviour in feral and domesticated horses. Risk factors for horses being attacked by wolves include body size, age, month of birth of the foals, group size, and stability of bands. Knowledge of the social organisation of horses with regard to defensive behaviour might help horse owners to adapt their management system of horses in the domesticated environment to reduce predation risk. In addition, by considering behaviours such as cohesion, synchronisation, and social bonding as collective interactive processes, we propose monitoring these behaviours and employing social network analysis to investigate how they influence anti-predator responses in horse groups, thereby providing insights into the role of group dynamics in enhancing defence strategies. • We review the social context of equine anti-predator behaviour. • Defence behaviours include cohesion, synchronised fleeing, and collision avoidance. • Predation risk factors are body size, age, birth month, group size and stability. • Keeping horses in groups is critical to their welfare and self-protection.