Multi-level combinatoriality in magpie non-song vocalizations

Abstract

Comparative studies conducted over the past few decades have provided important insights into the capacity for animals to combine vocal segments at either one of two levels: within- or between-calls. There remains, however, a distinct gap in knowledge as to whether animal combinatoriality can extend beyond one level. Investigating this requires a comprehensive analysis of the combinatorial features characterizing a species' vocal system. Here, we used a nonlinear dimensionality reduction analysis and sequential transition analysis to quantitatively describe the non-song combinatorial repertoire of the Western Australian magpie ( Gymnorhina tibicen dorsalis ). We found that (i) magpies recombine four distinct acoustic segments to create a larger number of calls, and (ii) the resultant calls are further combined into larger call combinations. Our work demonstrates two levels in the combining of magpie vocal units. These results are incongruous with the notion that a capacity for multi-level combinatoriality is unique to human language, wherein the combining of meaningless sounds and meaningful words interactively occurs across different combinatorial levels. Our study thus provides novel insights into the combinatorial capacities of a non-human species, adding to the growing evidence of analogues of language-specific traits present in the animal kingdom.

Ostrich (Struthio camelus) syrinx morphology and vocal repertoire across postnatal ontogeny and sex: Implications for understanding vocal evolution in birds

“…We reduced background noise in Audacity using the Noise Reduction function. This function subtracts the spectral envelope of background noise, which is selected by the user from sections of the recording in which only background noise is present (https://www.audacityteam.org/, Adret et al., 2018; Pantoja‐Sánchez et al., 2022; Walsh et al., 2023). To maximize the dynamic range of the spectrograms, we normalized the amplitude of each recording to its maximum amplitude.…”

Call combination production is linked to the social environment in Western Australian magpies ( Gymnorhina tibicen dorsalis )

“…Calls are separated by silent periods and segments are defined by smaller silent periods or sudden spectral shifts. Coloured bars demarcate classes of acoustically similar segments, labelled according to spectrographic appearance; refer to [21] for further detail on magpie combinatorial classification.…”

“…To build on our previous classification of the combinatorial repertoire [21], here we focus on the production of call combinations only, with the aim to shed light on the factors potentially influencing their production in magpies. In this study, we integrate natural observation and audio recording to generate a comprehensive dataset for investigating vocal production in juveniles, adults and at the group level.…”

“…species capable of continually acquiring/modifying vocalizations through life) may also be capable of combining calls (e.g. some elephant [19], cetacean [20] and songbird [21] species). In light of this evidence, it seems that repertoire size constraint should not be the only factor considered when investigating the potential factors influencing the occurrence of combinatoriality.…”

Anthropogenic noise affects vocalisation properties of the territorial song of Western Australian magpies

“…Western Australian magpies are a highly vocal subspecies of Australian magpie found in urban areas in the south-west of Western Australia (Dutour & Ridley, 2020; Johnstone, 2004). Magpies are highly territorial, and produce multiple complex vocalisations (Dutour & Ridley, 2020; Dutour et al, 2020; Walsh et al, 2023). The main territorial song of magpies – known as “carols” – are high-amplitude, slurred songs sung by individuals to advertise territory ownership and defend territories (Blackburn et al, 2022; Carrick, 1963; Dutour & Ridley, 2020).…”