MSc student
Advisor: Bernhard Wallner

Department of Behavioral & Cognitive Biology
University of Vienna

Social relationships are of central importance to primates and can be short- or long-term. Long-term affiliative relationships, also known as social bonds, increase individual fitness through better stress management, easier access to resources or support in social conflicts. Although male primates often compete with each other for food and mating partners, forming dominance hierarchies in the process, many species, including Japanese macaques (Macaca fuscata), also exhibit strong affiliative relationships between males.

Japanese macaques live in multi-male and multi-female groups, with females remaining in their birth group while males migrate at the onset of spermatogenesis (4–6 years). This migration of adolescent males makes it difficult to observe them in the wild and to record their social relationships. The enclosure at Affenberg Landskron (Austria) allows the macaques to move freely, maintain social contacts, or retreat to peripheral areas. Under these semi-free conditions, adolescent males can leave the core group but cannot disperse completely, providing a unique opportunity to study their social behaviour.

This study observed 23 adolescent males (4.5–8 years) and used the Composite Sociality Index (CSI) to determine their affiliative social relationships. This was determined by observing grooming, co-feeding, social play, proximity (1,3,5 metres) and body contact. The results showed that related and unrelated males developed social relationships of varying intensity. These findings provide valuable insights into a life stage that is difficult to observe in the wild and form the basis for future long-term studies on the integration success and social rank of male Japanese macaques.