Abstract

Understanding the drivers of how animals socialize and associate with each other in a population has insights into the ecology, biology, and behaviour of its members. Social Network Analysis (SNA) has been growing in popularity as a tool to understand the social patterns of animal populations, where multiple factors such as age and relatedness affect social patterns. The effect of genetic relatedness and age on the social patterns of an animal population exhibiting fission-fusion group dynamics (i.e. frequent changes in group membership) was assessed using a semi-domestic herd of female reindeer (Rangifer tarandus), situated in Kaamanen, Finland. Analyses were done using SNA in 2009 and 2011 during the breeding season (or rut), using GPS data. We found that females had distinct social groups (or communities) and associated non-randomly in both years; however, females did not spatially assort into communities based on genetic relatedness and age. Although age did not influence community structure, age affected association levels, where females socialized with others significantly less after the age of 7. We concluded that although genetic relatedness and age may not explain the non-random spatial associations between female reindeer during the rut, there may be other factors yet to be discovered that could play a role in their social organizations. Overall, our results provided insights into the social patterns of a population exhibiting fission-fusion group dynamics.