Spierings, M. J. | Search bioRxiv

bioRxiv2025

Common marmosets (Callithrix jacchus) do not differentiate between familiar and unfamiliar conspecifics based on pitch contour information

Previous studies suggest that vocal-learning species use variations of prosodic cues, such as changes in pitch, amplitude, or duration, in the conveying of meaning and emotions as well as individual recognition. Although it is known that the long-distance contact calls ("phee" calls) of common marmosets, a vocal non-learner, vary in prosodic information depending on individual characteristics, evidence of the species use of this information only recently started to emerge. In this study we tested 18 captive common marmosets (Callithrix jacchus) reactions to playbacks of familiar and unfamiliar individuals phee calls and extracted pitch-contour information. The playbacks consisted of i) natural phee calls from group members or unfamiliar conspecifics, or ii) synthesized pitch contours of familiar or unfamiliar phee calls following a natural or artificial syllable order as well as pure tones of similar frequency and duration. We found that although individuals seemed to show different reactions towards the natural calls of familiar and unfamiliar individuals, we did not find group level differences. Marmosets furthermore show significantly reduced interest in synthesized pitch contours compared to natural phee calls and did not differentiate between pitch contour playbacks and pure tone control stimuli, indicating that they did not categorize the pitch contours as conspecific calls. Our results suggest that extracted pitch contour information alone is not sufficient for marmosets to recognise conspecifics, however further studies are required to investigate the exact mechanism of individual recognition in marmosets.

animal behavior and cognition↗

bioRxiv2024

Artoo-Detoo: What imitating a Star Wars droid reveals on allospecific vocal imitation in parrots and starlings

Vocal production learning is a widespread and remarkable phenomenon. However, the underlying mechanisms of allospecific vocal imitation are poorly understood. Parrots and corvids are well known for their imitation abilities, but imitation accuracy has not yet been studied across species in a comparative context. We compared imitation accuracy between nine parrot species and European starlings based on imitation of monophonic and multiphonic sounds, produced by the Star Wars droid R2-D2. Our results show that starlings were better at imitating multiphonic sounds than parrots. However, no difference in imitation accuracy was found between parrots and starlings when imitating monophonic sounds. The differences in imitating accuracy are likely based on a physiological difference in syrinx anatomy, rather than on perceptual or cognitive differences between starlings and parrots. Between our nine tested parrot species, we found that parrots with larger brains (e.g., African greys and amazon parrots) were less accurate at imitating monophonic sounds than smaller brained budgerigars and cockatiels. The use of citizen science in our study shows the great potential this has to expand data collection beyond traditional studies. These findings contribute to a deeper understanding of the evolution of communication complexity in vocal learners. Significance StatementVocal imitation is a hallmark of complex communication in animals, yet the mechanisms driving species differences remain poorly understood. By comparing vocal imitation across nine parrot species and European starlings, we demonstrate, for the first time, that differences in syrinx anatomy, rather than cognitive or perceptual capacities, underlie species-specific variation in imitation accuracy. Contrary to traditional expectations, smaller-brained parrots outperformed larger-brained species in monophonic sound imitation. These findings challenge assumptions that brain size is directly linked to imitation accuracy and offer insights into the evolution of complex communication. We used citizen science to create a uniquely large dataset of species imitating the same source, demonstrating the powerful potential of this approach to broaden research in comparative cognition and vocal learning.

animal behavior and cognition↗