Dominance and plumage traits: meta-analysis and metaregression analysis

The study of avian signalling systems is an important avenue for research on animal communication. More specifically, the use of plumage traits to signal status or fighting ability has been extensively investigated for over 30 years. Yet, little is known about how strong and general the relationship between dominance and plumage traits is across different bird species. We conducted meta-analysis and metaregression analysis to investigate the relationship between dominance and plumage characteristics, using published literature on avian species. Our analyses tested possible moderators of this relationship, such as plumage trait and plumage colour, plumage manipulation, study location, type of dominance interaction, the use of model birds, type of dominance assessment and dominance context (breeding or nonbreeding). Our results revealed a significant effect size for the association between dominance and plumage. We found that the relationship between dominance and plumage was significantly influenced by the dominance assessment method used in the source study (direct or indirect). Furthermore, our analyses provide evidence that the role of plumage signalling may be similarly important during the breeding and nonbreeding seasons. We conclude that plumage signalling is a ubiquitous form of communicating status or fighting ability across bird species with different plumage types. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.