The Contribution of Mutual Grooming to Affiliative Relationships in a Feral Misaki Horse Herd

Abstract

Although herd size, structure, stability, and social rank among Misaki feral horses have been reported, no studies have been conducted on the affiliative relationships and interactions among members in a Misaki horse herd. The validity of three hypotheses regarding the function of social grooming, the affiliative relationship strengthening hypothesis, the worsened relationship restoring hypothesis, and the grooming parasite removal hypothesis, were tested in a Misaki feral horse (Equus caballus) herd in Cape Toi, Japan. All the nine horses in the “6m” herd were investigated in terms of kinship, grooming, aggression, proximity, social rank, and social network. Mutual grooming occurred only in pairs and was almost perfectly symmetrical. For each member, there was a significant negative correlation between total grooming received from other individuals and self-grooming. Controlling for kinship, there were significant positive partial correlations between mutual grooming and proximity and between aggression and proximity. No correlation was observed between aggression and mutual grooming. The results suggest that mutual grooming symmetry may contribute that both participants simultaneously benefit from parasite removal and strengthen affiliative relationships between seasonally changing herd members; however, mutual grooming did not foster restoring the worsened relationship following aggression promoted by physical proximity. The findings of this study may elucidate the mechanisms by which interactions between herd members are maintained or strengthened.

Behavioural and Physiological Changes in a Herd of Arabian Mares after the Separation of Individuals Differently Ranked within the Dominance Hierarchy

“…Hence, the increase in the rate of the ears held forward or pressed caudally and the decrease in the rate of the ears held laterally display an elevated emotional agitation in the remaining herd. The decrease in the rate of mutual grooming also corresponds with higher emotional arousal [ 4 , 13 ]. Hartmann et al [ 22 ] indicate neighing, snorting, defecation, increased locomotion, pawing and taking a vigilant posture as typical behaviours associated with the separation of an individual; however, they do not describe behaviours of the remaining group.…”

“…Social bonds are observed in many studies performed on feral and free-ranging horses slightly impeded by human interference e.g., [1][2][3][4] observed in outdoor-living or pastured horses under extensive human management when given the opportunity [5]. These observations show the natural propensity of horses to evolve long-term bonds within herds.…”

“…Social bonds are observed in many studies performed on feral and free-ranging horses slightly impeded by human interference e.g., [ 1 , 2 , 3 , 4 ]. The same social behaviour patterns are observed in outdoor-living or pastured horses under extensive human management when given the opportunity [ 5 ].…”

“…Under natural conditions, a herd usually consists of a stallion, one or more, often a few, adult, usually unrelated mares and their foals [ 6 ]. The mares evolve affiliative social integration, which has strong benefits for them, for example, it enables allogrooming, reduces harassment by males and increases foal birth rates [ 1 , 4 ]. Both mares and foals prefer to bond with peers within their sex [ 7 ].…”

Influence of Rank Stress on Behavior and Blood Indicators of A Young Horse

“…Such a strategy of behavior is based on various forms of interactions between individuals, each of which contributes to the viability of a given group, as a result of which the actions of its members become coordinated in space and time (Shimada 2020). As a result, the association of animals turns from a random accumulation into a structured community, which is based on hierarchical relationships, which are a complex of interconnected chains.…”