Contact call diversity in wild orange-fronted parakeet pairs, Aratinga canicularis

Contact calls are used to maintain cohesion and coordinate movements in social animals. The amount and type of identity information provided by contact calls are linked to social organization. Socially stable species often converge on shared group-specific contact calls. In socially fluid species, contact calls tend to be individually distinctive; evidence indicates that such calls are important for mediating individual-specific interactions. Dolphins, for example, will mimic the individually distinctive contact calls of other individuals while socializing. We examined contact calls in another fission–fusion species, the orange-fronted parakeet. Free-living and temporarily captive nonbreeding pairs as well as free-living breeding pairs were recorded. In all contexts, pairs produced multiple (up to nine) discrete contact call types, but like dolphins, typically favoured one to two individually specific variants per bird. The number of dominant variants produced and their evenness of use varied with context. Captive pairs produced the fewest dominants, using them with high evenness. Free-living nonbreeding pairs produced more dominants, and showed similarly high evenness. Breeding pairs varied widely in the number of dominants produced and their evenness of use, showing both the highest and lowest values of each. Latent acoustic measures revealed greater structural variation within and among dominants for free-living compared to captive pairs, presumably reflecting the increased opportunity for social interaction available in the wild. Across contexts, calls could be accurately assigned to pair using acoustic measures; however, within-pair call clustering was not greater than that between pairs. Pairs' calls were distinctive, but in a way that preserved individual variation.