Social Network Dynamics of Budgerigars and their Influence on Vocal Learning

Abstract

Social living involves a tradeoff between cooperation and competition, often giving rise to structured dominance hierarchies and intricate vocal communication. Budgerigars (Melopsittacus undulatus), with their capacity for open-ended vocal learning and complex social behaviors, offer a prime opportunity to examine these processes. In a mixed-sex captive flock studied over four weeks, we combined social network analysis of affiliative, aggressive, and display interactions with acoustic analyses of warble song syntax and contact call-like notes. Our results reveal a shallow yet consistent dominance hierarchy, where females generally outrank males. Notably, male displays typically used in courtship, also appear in male-male interactions as submission or appeasement signals, thereby mediating dominance relations. Warble song syntax and contact call repertoires exhibit strong individual signatures, yet both are shaped by social context. Males displaying to the same female showed convergence in their contact call repertoire, possibly signaling affiliation, while concurrently diverging in warble song syntax, thus maintaining distinct identities. Dominance status further influenced contact call structure, as more dominant males occupied central positions in the contact call similarity network. These findings suggest that subordinate males selectively converge with higher-ranked individuals, potentially as an affiliative signal. This study provides the first evidence for acoustic convergence as a mediator in dominance hierarchy, and a detailed account of their social organization in budgerigars. Overall, it underscores how intricate social networks and open-ended vocal learning intersect in parrots, informing broader discussions on the evolution of social communication systems.