Patterns of injury in zoo-housed spider monkeys: A problem with males?

The effects of alpha male removal on the social behavior of a group of olive baboons (Papio anubis)

In captivity, the managers of primate populations have removed individuals from their groups for medical and social reasons, but there has been little documentation regarding the consequences of this extraction on the sociality of the remaining individuals. This study provides information about the social effect of the alpha male removal in a group of olive baboons (Papio anubis) maintained at the Station of Primatology of CNRS (France). Data on social behavior was collected before and after male removal and then compared. Moreover, this social information was used to calculate the individual dominance index and the group dominance ranking. Overall, our results indicate that females seem to respond to male removal showing a more affiliative and tolerant behavior. However, the results also highlight the different coping mechanisms of females with this new social context. Therefore, this information could be useful for managers of primate populations, allowing them to anticipate the response of captive groups when facing certain sociodemographic changes. In this regard, we recommended creating a detailed procedure before the removal of the individuals that considers the characteristics of the individuals.

Network analysis as a tool to understand social development in spider monkeys

The emerging field of network science has demonstrated that an individual's connectedness within their social network has cascading effects to other dimensions of life. Like humans, spider monkeys live in societies with high fission-fusion dynamics, and are remarkably social. Social network analysis (SNA) is a powerful tool for quantifying connections that may vary as a function of initiating or receiving social behaviors, which has been described as shifting social roles. In primatology, the SNA literature is dominated by work in catarrhines, and has yet to be applied to the study of development in a platyrrhine model. Here, SNA was utilized in combination with R-Index social role calculation to characterize social interaction patterns in juvenile and adult Colombian spider monkeys (Ateles fusciceps rufiventris). Connections were examined across five behaviors: embrace, face-embrace, grooming, agonism, and tail-wrapping from 186 hr of observation and four network metrics. Mann-Whitney U tests were utilized to determine differences between adult and juvenile social network patterns for each behavior. Face-embrace emerged as the behavior with different network patterns for adults and juveniles for every network metric. With regard to social role, juveniles were receivers, not initiators, for embrace, face-embrace, and grooming (ps < .05). Network and social role differences are discussed in light of social development and aspects of the different behaviors.

Age related variation in male-male relationships in wild spider monkeys (Ateles geoffroyi yucatanensis)

In social organizations characterized by male philopatry, social relationships between males are argued to be the strongest. Little is known about the social relationships of philopatric male spider monkeys. To address this limitation, we investigated social relationships among individually recognized wild adult male spider monkeys from two well-habituated communities in the Yucatan Peninsula, Mexico, focusing on affiliative behaviors important in regulating male social relationships, including grooming, embracing, arm-wrapping, and grappling. We examined whether behaviors were reciprocated between male partners and whether age was a factor in how the behaviors were distributed or reciprocated, by examining differences between younger adult males (<10 years) and older adult males (≥14 years). Although we found evidence that affiliative behaviors were overall reciprocated between spider monkey adult males, there were pronounced differences in the interactions depending on their relative age. Reciprocation in grooming and embraces between same-age males suggests their relationships are valuable to both partners. Among different-age dyads, younger males gave more embraces than they received, were the initiators of grappling and arm-wrapped more often than with same-age males, suggesting relationships between younger and older males are more risky. This confirms that younger males are attracted to older males, probably because they value relationships with older males more than the reverse, but they are also at risk.