Vocalizations Reveal Species Differences in Endangered Lion Tamarins (Primates, Callitrichidae)

Acoustic communication is important for social cohesion and territory defense in forest primates, including the endangered lion tamarins (genus Leontopithecus). Although vocalizations of individual species have been studied, there is still no comparative analysis examining whether acoustic parameters can reliably distinguish among all four species. We hypothesized that species-specific differences in acoustic features allow discrimination among lion tamarin species, and we predicted that both spectral and temporal parameters would reveal interspecific variation. To test this, we analyzed seven shared vocalizations (long calls, whines, trills, rasps, clucks, tsicks, and peeps) from the black-faced lion tamarin (Leontopithecus caissara), golden lion tamarin (Leontopithecus rosalia), golden-headed lion tamarin (Leontopithecus chrysomelas), and black lion tamarin (Leontopithecus chrysopygus). Acoustic data were obtained from online sound libraries and analyzed using Raven Pro software. Spectral and temporal parameters, including frequency at 5% and 95%, peak frequency, center frequency, and bandwidth 90% were measured, followed by principal component analysis (PCA) and nonparametric statistical tests to identify species-specific differences. Our results revealed significant interspecific differences across multiple vocalizations, with spectral parameters being the most relevant for distinguishing species, whereas temporal parameters contributed less. L. caissara emerged as the most acoustically distinct species, while L. rosalia and L. chrysopygus exhibited the greatest vocal similarity. In conclusion, this study provides the first comparative analysis of seven vocalization types across all four lion tamarin species, establishing an acoustic baseline, confirming the importance of spectral parameters for species differentiation, and demonstrating the potential of vocalizations for conservation applications.