Vocal dialects in parrots: patterns and processes of cultural evolution

ABSTRACTVocal dialects have fascinated biologists for over 50 years. This mosaic pattern of geographic variation in learned vocalisations was first described in a songbird, and since that time most studies investigating dialects have focused on songbird species. Here we examine patterns of geographic variation in the calls of a different group of vocal learning birds, the parrots (order Psittaciformes). We summarise the growing literature on vocal variation in parrots, and complement this review with a survey of variation in the genus Amazona using calls from sound libraries. We find strikingly similar patterns to those previously found in songbirds. Over 90% of parrots examined in the literature, and 69% of Amazona species surveyed, showed geographic variation consistent with a propensity to share local call types. This trait is evolutionarily labile and widespread; within Amazona most clades contained species with and without geographic variation, and most major lineages of parrots include representativ...