Abstract: Coalitionary support in agonistic interactions represents cooperation because intervening in a fight is potentially costly to the donor of support but benefits the recipient. Here, we first review the characteristics of, and evolutionary forces favoring, intragroup coalitions in 49 species and find that patterns of intragroup coalition formation are remarkably similar between primates and nonprimates. We then test hypotheses suggesting kin selection, reciprocal altruism, and direct benefits as adaptive explanations for coalitionary interventions among adult female spotted hyenas (Crocuta crocuta) belonging to a large social group in Kenya. As predicted by kin selection theory, females supported close kin most often, and the density (connectedness) of cooperation networks increased with genetic relatedness. Nevertheless, kinship failed to protect females from coalitionary attacks. We found no evidence of enduring alliances based on reciprocal support among unrelated adult females. Instead, donors generally minimized costs to themselves, intervening most often during low-intensity fights and when feeding opportunities were unavailable. Females also gained direct benefits from directing coalitionary attacks toward subordinates. Finally, females monitored the number of dominant bystanders in the “audience” at fights and modified their level of cooperation based on this knowledge. Overall, hyenas made flexible decisions regarding whether or not to intervene in fights, modifying their tendency to cooperate based on multiple types of information about their immediate social and ecological environments. Taken together, these findings indicate that the combined evolutionary forces of kin selection and direct benefits derived from reinforcing the status quo drive coalitionary interventions among adult female spotted hyenas.

Abstract: During feeding behaviour, dogs were suddenly presented with 2D stimuli depicting the silhouette of a dog, a cat or a snake simultaneously into the left and right visual hemifields. A bias to turn the head towards the left rather than the right side was observed with the cat and snake stimulus but not with the dog stimulus. Latencies to react following stimulus presentation were lower for left than for right head turning, whereas times needed to resume feeding behaviour were higher after left rather than after right head turning. When stimuli were presented only to the left or right visual hemifields, dogs proved to be more responsive to left side presentation, irrespective of the type of stimulus. However, cat and snake stimuli produced shorter latencies to react and longer times to resume feeding following left rather than right monocular visual hemifield presentation. Results demonstrate striking lateralization in dogs, with the right side of the brain more responsive to threatening and alarming stimuli. Possible implications for animal welfare are discussed.

Abstract: Predation is a major force in shaping biological communities, both over ecological and evolutionary timescales. In response to predation pressure, prey have evolved characteristics designed to mitigate predation pressure. We evaluated predator foraging biases in relation to prey characteristics across 16 vertebrate communities. We show that although predator biases vary, some prey traits are consistently associated with predator diet composition. Within their acceptable prey size range, predators show positive bias toward larger bodied prey, small-brained prey (controlling for body size), small group size, and terrestriality. Thus, whether predator foraging decisions are passive or active, predator choice exerts differential pressure on prey species according to prey characteristics. Predator biases also were positively associated with early age at maturity, supporting the role of mortality in driving life-history characteristics. These results support several theoretical models of predation including its role as a selective force driving evolutionary changes in life history, brain size and sociality, optimal diet theory, and antiapostatic predation.

Abstract: Summary For animals living in mixed-sex social groups, females who form strong social bonds with other females live longer and have higher offspring survival [1–3]. These bonds are highly nepotistic, but sometimes strong bonds may also occur between unrelated females if kin are rare [2, 3] and even among postdispersal unrelated females in chimpanzees and horses [4, 5]. Because of fundamental differences between the resources that limit reproductive success in females (food and safety) and males (fertilizations), it has been predicted that bonding among males should be rare and found only for kin and among philopatric males [6] like chimpanzees [7–9]. We studied social bonds among dispersing male Assamese macaques (Macaca assamensis) to see whether males in multimale groups form differentiated social bonds and whether and how males derive fitness benefits from close bonds. We found that strong bonds were linked to coalition formation, which in turn predicted future social dominance, which influenced paternity success. The strength of males' social bonds was directly linked to the number of offspring they sired. Our results show that differentiated social relationships exert an important influence on the breeding success of both sexes that transcends contrasts in relatedness.

Abstract: Based on plasma cortisol concentrations it is widely accepted that transport is stressful to horses. So far, cortisol release during transport has not been evaluated in depth by non-invasive techniques such as analysis of salivary cortisol and faecal cortisol metabolites. Transport also causes changes in heart rate and heart rate variability (HRV). In this study, salivary cortisol, faecal cortisol metabolites, heart rate and HRV in horses transported by road for short (one and 3.5 h) and medium duration (8 h) were determined. With the onset of transport, salivary cortisol increased immediately but highest concentrations were measured towards the end of transport (4.1 ± 1.6, 4.5 ± 2.6, 6.5 ± 1.8 ng/ml in horses transported for one, 3.5 and 8 h, respectively). Faecal cortisol metabolite concentrations did not change during transport, but 1 day after transport for 3.5 and 8 h had increased significantly (p < 0.01), reflecting intestinal passage time. Compared to salivary cortisol, changes in faecal cortisol metabolites were less pronounced. Heart rate increased and beat-to-beat (RR) interval decreased (p < 0.05) with the onset of transport. Standard deviation of heart rate increased while root mean square of successive RR differences (RMSSD) decreased in horses transported for 3.5 (from 74 ± 5 to 45 ± 6 ms) and 8 h (from 89.7 ± 7 to 59 ± 7 ms), indicating a reduction in vagal tone. In conclusion, transport of horses over short and medium distances leads to increased cortisol release and changes in heart rate and HRV indicative of stress. The degree of these changes is related to the duration of transport. Salivary cortisol is a sensitive parameter to detect transient changes in cortisol release.