Abstract: Third-party interventions are defined as the interruption of dyadic interactions by third animals through direct physical contact, interposing or threats. Previous studies focused on the analysis of interventions against agonistic encounters. However, there have been no evaluations of interventions against affiliative behaviours, particularly in relation to the intervening animal�s social relationships and its social and spatial position. Horses, Equus caballus, are an interesting model species, as interventions against affiliative interactions occur more frequently than against agonistic interactions. In this study, 64 feral horses displayed 67 interventions in affiliative interactions and eight interventions in agonistic interactions within the observation period. We analysed the interventions in affiliative encounters, and found that it was mainly higher-ranking females that intervened in the affiliative interactions of group mates in the stable horse harems. The intervening animals took an active part in affiliative and agonistic encounters within the group, but did not occupy particular social roles or spatial positions. They intervened in affiliative interactions in which group mates with which they had social bonds interacted with other members of the group. They targeted the nonbonded animal and approached the one with which they were socially bonded. We suggest some species use third-party interventions in affiliative interactions to prevent competition for preferred social interaction partners from escalating into more costly agonistic encounters.

Abstract: A central question in the interspecific human/animal relationship is how domestic animals perceive humans as a significant element of their environment. In this study, we tested the hypothesis that the use of positive or negative reinforcement in horse training may have consequences on the animals’ perception of humans, as a positive, negative or neutral element. Two groups of ponies were trained to walk backwards in response to a vocal order using either positive or negative reinforcement. Heart rate monitors and behavioural observations were used to assess the animals’ perception of humans on the short (just after training) and long (5 months later) terms. The results showed that the type of reinforcement had a major effect on the subsequent animals’ perception of familiar and unfamiliar humans. Negative reinforcement was rapidly associated with an increased emotional state, as revealed by heart rate measurements and behavioural observations (head movements and ears laid back position). Its use led the ponies to seek less contact with humans. On the contrary, ponies trained with positive reinforcement showed an increased interest in humans and sought contact after training. This is especially remarkable as it was reached in a maximum of 5 sessions of 1 to 3 min (i.e. 5 to 15 min) and had lasting effects (visible after 5 months). Even learning was positively influenced by positive reinforcement. Overall, horses seem capable of associating humans to particular experiences and display extended long-term memory abilities.

Abstract: Contraception is often considered for population control of wildlife that is otherwise protected from more traditional management strategies, though little is known about the behavioral consequences of contraception in wild populations of socially complex animals. Feral horses, Equus caballus, in the western United States are ideal candidates for contraceptive management due to broad scale federal protection, reported herd growth rates of 15-25% per year, and finite public land allocated for them. We investigated influences of the immunocontraceptive porcine zona pellucida (PZP) on social behavior within bands of feral horses in three discrete populations for 4 years. Each band consisted of a single stallion and a harem of adult females (>1 years old) and their foals, as well as associated yearling males and females. Four mutually exclusive behaviors (herding, reproductive, harem tending, and agonism) were analyzed to investigate the difference between behaviors initiated by band stallions toward control mares and contracepted mares within the bands. Additionally, spatial relationships between each stallion and each harem female were analyzed to assess possible passive interactions. A candidate set of 22 hierarchical mixed effects models, using the discrete populations as a random effect on various fixed effects, was analyzed by restricted maximum likelihood estimation. The most supported models were selected by corrected Akaike"s Information Criteria (AICc). Analyses were done on 3 female age cohorts based on distinct fecundity rates: 2 to 5 year olds, 6 to 14 year olds, and > 14 year olds. Stallions herded control mares in the 6 to 14 year cohort more than contracepted mares (n=128, P=0.037) with treatment being the most supported effect, but foal presence (dependent foal) also contributed significantly to the model. Contracepted mares received more reproductive behaviors than control mares in the 6 to 14 year cohort (n = 151, P=0.020). No differences were detected in herding or reproductive behaviors in
the least fecund groups, the 2 to 5 year olds and &#8805; 15 year olds. The only independent variable in the most supported model for reproductive behavior was treatment, and the covariates of foal presence, band residence (resident or transient female), band size, and body condition did not contribute. There were no differences in any age cohort for harem tending or agonism. Spatially, stallions maintained closer relationships with 2 to 5 year old contracepted females than with the same age control females (n=136, P < 0.001) while the group was feeding (at its most dispersed structure), but there were no differences while the band was resting or in locomotion. There were no spatial differences detected in the other age cohorts. Given the polyestrous nature and high fecundity of feral horses, the observed difference in reproductive behaviors between treatment groups was not surprising; however, the difference detected in herding rates was an unexpected behavioral modification. This change in herding behavior suggests that further investigation is needed to determine if PZP immunocontraception has an underlying influence on mare social rank, band structure, and band stability, as well as the scope and long-term importance of these behavioral dynamics.

Abstract: Selection pressures during domestication are thought to lead to an enhanced ability to use human-given cues. Horses fulfil a wide variety of roles for humans and have been domesticated for at least 5000 years but their ability to read human cues has not been widely studied. We tested the ability of 28 horses to attend to human-given cues in an object choice task. We included five different cues: distal sustained pointing, momentary tapping, marker placement, body orientation and gaze (head) alternation. Horses were able to use the pointing and marker placement cues spontaneously but not the tapping, body orientation and gaze alternation cues. The overall pattern of responding suggests that horses may use cues that provide stimulus enhancement at the time of choice and do not have an understanding of the communicative nature of the cues given. As such, their proficiency at this task appears to be inferior to that of domestic dogs, Canis lupus familiaris, but similar to that of domestic goats, Caprus hircus.

Abstract: Abstract Feral horses (Equus caballus) have a complex social structure, the stability of which is important to their overall health. Behavioral and demographic research has shown that decreases in group (or band) stability reduce female fitness, but the potential effects on the physiological stress response have not been demonstrated. To fully understand how band stability affects group-member fitness, we need to understand not only behavioral and demographic, but also physiological consequences of decreases to that stability. We studied group changes in feral mares (an activity that induces instability, including both male and female aggression) on Shackleford Banks, NC. We found that mares in the midst of changing groups exhibit increased fecal cortisol levels. In addition, mares making more group transfers show higher levels of cortisol two weeks post-behavior. These results offer insights into how social instability is integrated into an animal’s physiological phenotype. In addition, our results have important implications for feral horse management. On Shackleford Banks, mares contracepted with porcine zona pellucida (PZP) make approximately 10 times as many group changes as do untreated mares. Such animals may therefore be at higher risk of chronic stress. These results support the growing consensus that links between behavior and physiological stress must be taken into account when managing for healthy, functional populations.