The effect of perturbation on social networks and vocal learning in parrots

Abstract

Group living is a key strategy adopted by a diverse group of organisms ranging from large carnivorous mammals like lions (Panthera leo) to insects like bees, beetles, and wasps. Social behavior among parrots (Psittaciformes) has been documented since 1960s. Sociality influences key traits such as warble production and reproductive physiology in parrots. Parrots exhibit fission-fusion dynamics, stable dominance hierarchies and are open-ended vocal learners, capable of modifying vocalizations throughout their life. As parrots are popular pets, they are a tractable system to study and experimentally manipulate social behavior in captivity. Hence, carefully planned manipulation experiments on captive parrots can help us understand changes in social interactions and vocal communications when individuals leave or join the group. We performed experimental removal and reintroduction of top-ranked male and its paired female in two parrot species- the budgerigar (Melopsittacus undulatus) and rosy-faced lovebirds (Agapornis roseicollis). Careful tracking of social interactions revealed retention of broad interaction patterns, but specific network properties showed a trend of disturbance followed by recovery over the course of the experiment. Display behaviors increased in both the species, hinting at their possible role for negotiating social position. Preliminary observations of contact call usage patterns indicated that budgerigars increased acoustic space use followed by convergence in specific regions. On the other hand, lovebirds maintained initial call clusters, but changed relative cluster use. This thesis hints at possible properties exhibited by fission-fusion societies and establishes an experimental and analytical paradigm to examine social behavior and vocal communication in such social systems.