Relationship between rank and plasma testosterone and cortisol in red deer males (Cervus elaphus)
The objective of this study was to assess the effect of a change in the social composition in a group of red deer males on the relationship between their rank and testosterone. A group of twelve adult red deer males (Cervus elaphus) was tested in two social settings. From April 15 to June 9 (Period […]
Male and Female Aggression: Lessons from Sex, Rank, Age, and Injury in Olive Baboons
Aggression is ubiquitous, influencing reproduction through inter- and intraspecific effects in ways that reflect life-history strategies of species. In many social mammals, females remain in their natal group for life, whereas males emigrate and compete for rank in other social groups. Competition for rank is inherently risky. Therefore, it has long been hypothesized that risks […]
Infanticide risk and infant defence in multi-male free-ranging sooty mangabeys, Cercocebus atys
For years, infanticide by males was thought to be unlikely in multi-male primate species. Recent studies have, however, presented evidence of infanticide in such species and a recent model by Broom and colleagues predicts that males’ age and rank influence the occurrence of infanticide: youngest and highest-ranking immigrant males are more likely to commit infanticide […]
Social Feeding Decisions in Horses (Equus caballus)
Like many other herbivores, in a natural environment equids feed on rather evenly distributed resources. However, the vegetation in their vast habitats constantly changes. If food is plentiful only little competition occurs over food, and in non-competitive situations domestic horses tend to return to the same feeding site until it is overgrazed. In contrast, they […]
Friendship among Adult Female Blue Monkeys (Cercopithecus mitis)
A study group of blue monkeys in the Kakamega Forest, Kenya, provides data on friendly relationships between adult females. Females are invariably antagonistic toward members of other groups, and collaborate with their own groupmates in defending territorial boundaries. Females are primarily responsible for these aggressive intergroup encounters, which occur every other day on average. Encounters […]
Effects of reproductive condition and dominance rank on cortisol responsiveness to stress in free-ranging female rhesus macaques
The hypothalamic–pituitary–adrenal (HPA) axis modulates individuals’ physiological responses to social stress, which is an inevitable aspect of the daily lives of group-living animals. Previous nonhuman primate studies have reported that sex, age, rank, and reproductive condition influence cortisol levels under stressful conditions. In this study we investigated cortisol responses to stress among 70 multiparous, free-ranging […]
Long-term dominance relationships in female mountain gorillas: strength, stability and determinants of rank
A common practice in studies of social animals is to rank individuals according to dominance status, which has been shown to influence access to limited resources and stability of social relationships, and may in turn correlate with reproductive success. According to the socioecological model for primates, most female dominance relationships are either nepotistic or virtually […]