The Social Life of Pigs: Changes in Affiliative and Agonistic Behaviors following Mixing

This study investigated potentially affiliative behaviors in grow-finish pigs, how these behaviors changed over time and their relationship to agonistic behaviors. A total of 257 Yorkshire barrows were observed for agonistic (reciprocal fights, attacks) and affiliative (nosing, play, non-agonistic contact) behaviors after mixing (at 10 weeks of age), and weeks 3, 6, and 9 after mix. The least square means of affiliative behaviors were compared across time points. Relationships among affiliative and agonistic behaviors were assessed using generalized linear mixed models. Non-agonistic contact with conspecifics increased until week 6 then remained stable between weeks 6 and 9. Nosing was highest at mix, then decreased in the following weeks. Play was lowest at mix and highest at week 3. Affiliative behaviors were negatively related with aggression at mix (p < 0.001). Pigs who engaged in play and nosing behaviors were more likely to be involved in agonistic interactions in the weeks after mixing (p < 0.05), while pigs engaging in non-agonistic contact were less likely to be involved in agonistic interactions (p < 0.001). There appear to be relationships between affiliative and agonistic behaviors in pigs, with contact being the most predictive of less aggression. Future studies could focus on promoting positive non-agonistic contact in unfamiliar pigs as a way to mitigate aggressive interactions.

Behavioral Responses of Captive Corvids to the Presence of Visitors

Behavioral responses of captive animals to the presence of visitors in zoos and wildlife parks can be interpreted as signs of negative (disturbance), neutral or positive (enrichment) welfare. In the present study, we investigated behavioral responses of captive common ravens, Corvus corax and crows, Corvus corone, to the presence of visitors in general and to the proximity or distance of visitors to the aviary respectively. Duration of affiliative behaviors, feeding and stress-related behaviors did not change when visitors were present compared to control situations without visitors being present. Both corvid species showed less head up behavior when visitors were in sight compared to the control condition. In contrast, preening of crows significantly increased when visitors were within two meters of the aviary compared to the control condition. The same relationship was found in regard to increase in vocalization for common ravens, but not for crows. Our results indicate that corvids, housed in a wildlife park for several years, still show behavioral responses to the presence of human visitors in close proximity to their enclosure. Overall, we did not find clear indications for reduced welfare due to visitor presence, such as increased locomotion or stress-related behaviors. We therefore conclude that the described behavioral changes are not indicative of any negative welfare impacts of visitor presence.

Variability of social interactions in new versus established relationships in female degus

When a behaving system explores a new environment or stimulus it varies its behavior to ensure proper sampling. As contingencies are learned, behavioral variance can give-way to routines and stereotypies. This phenomenon is common across a range of learning systems, but has not been well studied in the social domain in which the stimulus an agent investigates, another individual, is reactive to the agent’s behaviors. We examined the effects of social novelty on interaction variability in laboratory-reared, female degus, known to readily express affiliative behaviors with initially unfamiliar, unrelated individuals. Degus were presented with a series of 20 minute, dyadic “reunion” sessions across days, interleaving exposures to familiar and unfamiliar same-sex conspecifics. We found that dyads could be distinguished from one-another by their interactive behaviors, suggesting dyad-specific social relationships. Following the first session, stranger dyads were unexpectedly easier to differentiate than cagemates due to a combination of higher diversity of behavior between dyads and, in some cases, lower variability within dyads. Some evidence could be found for higher variability in stranger interactions within the first two exposures, though within-session variability increased in cagemates across reunions, ultimately exceeding levels in strangers. We also observed that while strangers interacted more than cagemates, this could be traced to only 30% of the animals and the higher interaction levels did not attenuate over sessions or after co-housing the animals. No strong differences were observed in the temporal structure of social behavior between the two groups. Results reveal that new relationships in adult, female degus are more diverse but not more variable compared with established relationships, particularly after the first social exposure. Given known tendencies of female degus to form and maintain new relationships, these findings are consistent with the notion that higher interaction variability may be maladaptive to building social coordination and trust.

Horse Behavior towards Familiar and Unfamiliar Humans: Implications for Equine-Assisted Services

While human benefits of animal-assisted therapy programs have been documented, relatively little research has been conducted on behavioral factors that predict a successful equine-assisted services (EAS) horse. This study compares the behavior of experienced and non-experienced EAS horses as well as horses selected for future EAS work in a series of sociability and temperament tests. No significant differences were found between experienced and non-experienced horses in the sociability measures or for most of the temperament tests; however, significant differences were found between groups in the brushing test, with non-experienced horses showing more affiliative behaviors towards the familiar handler and unfamiliar persons. No significant differences were found between selected and non-selected horses in the temperament tests. However, non-selected horses were found to show significantly more affiliative behaviors towards a familiar person during a sociability test compared with selected horses. These findings suggest that the social behavior and temperament of EAS horses may not be significantly different from other available horses not selected for EAS work. Instead, these decisions may primarily reflect subjective impressions of fit. Interestingly, on measures where significant differences were identified, the horses not actively engaged in or selected for therapy were the ones that showed greater affiliative responses to familiar and unfamiliar humans. Reasons for why this may be, as well as future directions in EAS selection, are discussed.

Implementing network approaches to understand the socioecology of human-wildlife interactions

Human population expansion into nonhuman animals’ habitats has increased interest in the behavioral ecology of human-wildlife interactions. To date, however, whether and how wild animals and their conspecifics form non-random associations in terms of when or where they interact with humans still remains unclear. Here we adopt a comparative approach to address this gap, using social network analysis (SNA). SNA, increasingly implemented to determine human impact on wildlife spatial and social ecology, can be a powerful tool to understand how animal socioecology influences the spatiotemporal distribution of human-wildlife interactions. For 10 groups of rhesus, long-tailed, and bonnet macaques (Macaca spp.) living in anthropogenically-impacted environments in Asia, we collected data on human-macaque interactions, animal demographics, and macaque-macaque agonistic and affiliative social interactions. We constructed ‘human-interaction networks’ based on associations between macaques that interacted with humans within the same time and spatial locations, and social networks based on macaque-macaque allogrooming behavior, affiliative behaviors of short duration (agonistic support, lip-smacking, silent bare-teeth displays, and non-sexual mounting), and proximity. Pre-network permutation tests revealed that, for all macaque groups, human-interaction networks showed non-random structures. GLMMs revealed that individuals’ connectedness within human-interaction networks were positively associated their connectedness within affiliation social networks, and social proximity networks although this effect varied across species (bonnets &gt; rhesus &gt; long-tailed). Male macaques were more well-connected in human-interaction networks than females. Neither macaques’ connectedness within grooming social networks nor their dominance ranks had an impact on human-interaction networks. Our findings suggest that, in challenging, time-constraining anthropogenic environments, less time-consuming affiliative behaviors and additionally greater social tolerance (especially in less ecologically flexible species with a shorter history of exposure to human activity) may be key to animals’ maintaining strong social connections. Subsets of these animals may also utilize greater exploratory tendencies and life-histories that are less energetically demanding in the long-term. Both of these strategies may contribute to animals’ propensities to engage in joint risk-taking by being near and engaging with humans. From conservation and public health perspectives, human-interaction networks may inform interventions to mitigate zoonotic disease transmission and move human-wildlife interactions from conflict towards co-existence.

Post-weaning stroking stimuli induce affiliative behavior toward humans and influence brain activity in female rats

Gentle touch contributes to affiliative interactions. We investigated the effects of gentle stroking in female rats on the development of affiliative behaviors toward humans and we exploratively examined brain regions in which activity was influenced by stroking. Rats that had received stroking stimuli repeatedly after weaning emitted 50-kHz calls, an index of positive emotion, and showed affiliative behaviors toward the experimenter. Hypothalamic paraventricular oxytocin neurons were activated in the rats after stroking. The septohypothalamic nucleus (SHy) in the post-weaningly stroked rats showed decreased activity in response to stroking stimuli compared with that in the non-stroked control group. There were negative correlations of neural activity in hypothalamic regions including the SHy with the number of 50-kHz calls. These findings revealed that post-weaning stroking induces an affiliative relationship between female rats and humans, possibly via activation of oxytocin neurons and suppression of the activity of hypothalamic neurons.

Gender Differences in the Relationship between Anger and Aggressive Behavior

Evidence is mixed regarding differences in prevalence of aggressive behavior, with many (though not all) studies suggesting that men are more aggressive than women. Furthermore, while aggression often occurs in response to provocation-induced anger, this relationship may be stronger for men; women may be more likely to engage in non-aggressive (e.g., affiliative) behaviors in response to provocation, particularly at low-level provocation. This study examined gender differences in aggression as well as differences in the relationship between anger and aggression for men and women. Adults ( N = 424) participated in a behavioral aggression task, and a subset of participants ( n = 304) completed a questionnaire assessing trait levels of anger as part of a larger study at a large midwestern university. Results indicated that while men and women aggressed at similar levels, aggression was significantly associated with trait anger for men only, at low levels of provocation, with only a trending relationship for high provocation. This suggests that while men and women may be equally aggressive in certain situations, this behavior may be differentially associated with anger.

The Equipment Used in the SF6 Technique to Estimate Methane Emissions Has No Major Effect on Dairy Cow Behavior

The natural behavior of animals can be disrupted by the techniques and materials of research methodologies. This study aimed to evaluate the effect of the equipment used in the SF6 tracer technique to estimate enteric methane emissions on the behavior of lactating dairy cows. The cows (n = 24) were allocated to one of two diets: CONTROL and experimental diet (MIX). Behavior was assessed through video recordings between milking times during four phases: 3 days before fitting the cows with the SF6 equipment (PRE), first 2 days after the cows were fitted with the SF6 equipment (ADAP), 3 days during methane emission measurements (MEAS), and 2 days after the SF6 equipment removal (POST). The behaviors recorded included eating, ruminating or idling, resting, and others. Affiliative or agonistic and discomfort behaviors (scratching or pushing the equipment) were also recorded. Lying time was recorded over 14 days using dataloggers fitted to the cows' leg. Milk production and feed intake were recorded daily. MIX cows ruminated more than CONTROL cows (P = 0.05). The cows ruminated more at MEAS than in any other phase (P &lt; 0.01). Time spent idling gradually decreased from PRE to MEAS for MIX cows (P &lt; 0.01). The cows were lying down longer in MEAS than in ADAP and POST (P &lt; 0.01). The time spent lying with the head down was shorter during PRE and ADAP than during POST (P &lt; 0.05). No difference was observed in the occurrence of discomfort or agonistic behaviors (P &gt; 0.05). Affiliative behaviors occurred more often in ADAP than in MEAS (P &lt; 0.05). There was no difference between phases in daily lying time, number of lying bouts per day, or mean bout duration (P &gt; 0.05). Milk production was not influenced by the SF6 equipment (P &gt; 0.05). Dry matter intake was higher for CONTROL cows (P &lt; 0.01), and it decreased from PRE to MEAS (P &lt; 0.01). However, milk yield did not differ between cows wearing the SF6 equipment and those without it (P &gt; 0.05). We conclude that the SF6 equipment had a minimal effect on dairy cow behavior.