What imitating an iconic robot reveals on allospecific vocal imitation in parrots and starlings

Vocal production learning is a remarkable ability, exclusively present in a few mammalian species and three bird clades. Besides learning conspecific vocalizations, vocal production can also lead to integration of allospecific sounds in an animal's repertoire. While parrots and songbirds are well known for their allospecific imitation abilities, structural differences in imitation accuracy across species remain unclear. This study compared nine parrot species and European starlings on their ability to imitate monophonic and multiphonic sounds created for the Star Wars character R2-D2. These complex synthesizer sounds allow for a strong comparative analysis with the same spectral complexity imitated by multiple species. Our results show that starlings have a higher accuracy when imitating multiphonic sounds than parrots. However, both groups performed equally well when imitating monophonic sounds. Differences in imitation accuracy likely stem from syrinx anatomy rather than perceptual or cognitive disparities. Among parrots, species with smaller brains, such as budgerigars and cockatiels, outperformed larger-brained African greys and amazon parrots in monophonic sound imitation. Our study highlights the great potential of citizen science for expanding data collection beyond traditional studies and sheds light on the evolution of communication complexity in vocal learners.