Abstract: Abstract One mechanism to resolve conflict among group members is third party intervention, for which several functions, such as kin protection, alliance formation, and the promotion of group cohesion have been proposed. Still, empirical research on the function of intervention behaviour is rare. We studied 40 cases of intervention behaviour in a field study on 13 semi-wild bachelor horses (Equus ferus przewalskii) in (a) standard social situations, and (b) when new horses joined the group (i.e. introductions). Only interventions in agonistic encounters were analysed. Eight of 13 animals directed intervention behaviour toward threatening animal in agonistic encounters of group members. One stallion was particularly active. The stallions did not intervene to support former group mates or kin and interventions were not reciprocated. In introduction situations and in standard social situations, the interveners supported animals which were lower in rank, but targeted, threatening animals of comparable social rank. After introductions, stallions received more affiliative behaviour from animals they supported and thus appeared to intervene for alliance formation. In standard social situations, interveners did not receive more affiliative behaviour from animals they supported and may primarily have intervened to promote group cohesion and to reduce social disruption within the group.

Abstract: Every animal species has particular environmental requirements that are essential for its welfare, and when these so-called “basic needs” are not fulfilled, the animals suffer. The basic needs of horses have been claimed to be social contact, social companionship, free movement and access to roughage. To assess whether horses suffer when one or more of the four proposed basic needs are restricted, we examined several studies (n = 38) that reported behavioural and physiological reactions to these restrictions. We assigned the studies according to the four types of responses investigated: (a) Stress, (b) Active, (c) Passive, and (d) Abnormal Behaviour. Furthermore, the number of studies indicating that horses reacted to the restrictions were compared with the number of studies reporting no reaction. The limited number of studies available on single management restrictions did not allow conclusions to be drawn on the effect of each restriction separately, especially in the case of social companionship. However, when combinations of social contact, free movement and access to roughage were restricted, many of the horses had developed responses consistent with suffering. Passive Responses, indicating acute suffering, and Abnormal Behaviour, indicating suffering currently or at some time in the past, were especially clearly demonstrated. This provides further evidence of the usefulness of assessing behavioural parameters in combination with physiological measurements when evaluating horse welfare. This meta-analysis of the literature confirms that it is justified to claim that social contact, free movement and access to roughage are basic needs in horses.

Abstract: Viele Pferdebesitzer bevorzugen aus Angst vor aggressiven Interaktionen und Verletzungsgefahr der Tiere untereinander die Einzelhaltung, obwohl von Tierschutzorganisationen die Gruppenhaltung für Pferde empfohlen wird. In dieser Studie beobachteten wir während des alltäglichen Soziallebens als auch bei der Eingliederung von neuen Gruppenmitgliedern das Sozialverhalten, insbesondere das Aggressionsverhalten, von elf Gruppen domestizierter Pferde (Equus caballus) verschiedener Größe und Zusammensetzung. Während des alltäglichen Soziallebens hatten die Gruppe und der Paddock-Typ (Gras / kein Gras) keinen Einfluss auf die Verhaltensweisen, wohingegen die Paddockgröße unter 10000 m2 einen signifikanten Einfluss auf die submissiven Verhaltensweisen (GzLM; n=56; t=-2.061, P=0.044) und einen nicht signifikanten Einfluss auf die aggressiven Verhaltensweisen (GzLM; n=56; t=-1.782, P=0.081) hatte. Allerdings verringerten sich sowohl die aggressiven als auch die submissiven Verhaltensweisen mit steigendem Platzangebot bis zu 10000 m2 (Spearman rank Korrelation; n=56; aggressive Verhaltensweisen: r = -0.313, P = 0.019; submissive Verhaltensweisen: r = -0.328, P = 0.014). Während den Eingliederungen reduzierten sich die Aggressionen pro Stunde mit der Vergrößerung des Platzangebotes (Spearman rank Korrelation; n=28; r=-0.402, P=0.034). Dies zeigte sich noch deutlicher, wenn Beobachtungen mit einem Platzangebot von über 10000 m2 ausgeschlos- sen wurden (Spearman rank Korrelation; n=23; r=-0.549, P=0.007). Während des alltäglichen Soziallebens näherte sich der Aggressionslevel der Nulllinie an, wenn das Platzangebot pro Pferd mehr als 331 m2 betrug. Deshalb empfehlen wir zur Reduzierung des Aggressionslevels und des Verletzungsrisikos von sozial gehaltenen Pferdegruppen ein Platzangebot von mindestens 331 m2 pro Pferd.
[Even though animal welfare organisations propose group housing for horse welfare, many owners stable horses individually for fear of aggressive interactions and injury risks. In the present study we observed social behaviour, and especially aggressiveness, in eleven domestic horse groups (Equus caballus) of different size and composition, in basic social situations and when new group members were introduced. During basic social situations, the group and the type of paddock (grass / no grass) had no effect on any of the behaviours, where- as the enclosure size below 10,000 m2 had a significant effect on submissive behaviour (GzLM; n=56; t=-2.061, P=0.044) and an insignificant effect on aggressive behaviour (GzLM; n=56; t=-1.782, P=0.081). However, aggressive and submissive behaviour dimi- nished with the increase of enclosure sizes up to 10,000 m2 (Spearman rank correlation; n = 56; aggressive behaviour: r = -0.313, P=0.019; submissive behaviour: r=-0.328, P=0.014). During introductions, aggression levels per hour decreased with any increase of enclosure size (Spearman rank correlation; n=28; r=-0.402, P=0.034) and even more when enclosure sizes above 10,000 m2 were excluded (Spearman rank correlation; n=23; r=-0.549, P=0.007). During basic social situations the aggression level approached zero when the space allowance was more than 331 m2 per horse. We therefore recommend keeping horse groups in an enclosure with at least 331 m2 per horse to reduce aggression and injuries.]