Temporal dynamics of social hierarchy formation and maintenance in male mice

Dominance hierarchies emerge when individuals must compete for access to resources such as food, territory or mates. Here, using traditional and network social hierarchy analysis, we show that 10 groups of 12 male laboratory CD1 mice living in large vivaria consistently form extremely linear dominance hierarchies. Within each hierarchy we determine that every individual mouse has a unique social rank and behaves with a high degree of consistency in their agonistic behaviour towards other individuals. Using temporal pairwise comparison Glicko ratings and social network triangle transitivity measures, we demonstrate that these hierarchies emerge rapidly, and that initial aggression is not predictive of later dominance. We also show that groups vary in how unequally power is distributed over time as social networks stabilize. Our results demonstrate that an ethologically relevant housing paradigm coupled with extensive behavioural observations provides a strong framework for investigating the temporal patterning of mouse dominance hierarchies and complex social dynamics. Furthermore, the statistical methods described establish a strong basis for the study of temporal dynamics of social hierarchies across species. (C) 2016 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.