A quantitative assessment of dialectal variation in a linguistic transition zone: spatial insights from vernacular bird names in southeastern Spain

Understanding the factors underlying dialectal variation across culturally and environmentally heterogeneous territories remains a major challenge in geolinguistic and ethnobiological research. The province of Almería (southeastern Spain) has often been described as a linguistic transition zone within the Hispanic domain, where features of eastern Andalusian and Murcian converge as a consequence of its historical trajectory and geographical position. However, quantitative assessments of this characterization remain limited. This study examined whether similarities in vernacular bird names and named bird species reveal geographically structured dialectal differentiation within Almería and whether the resulting spatial patterns could be interpreted in relation to socio-cultural or geo-environmental variation. Vernacular ornithonyms constituted the empirical basis of the analyses. Quantitative approaches were applied to a comprehensive dataset of popular denominations recorded across the seven comarcas under an exploratory framework informed by previous dialectological, ethnobiological and territorial evidence. The distribution of vernacular names revealed a spatial differentiation between southwestern and northeastern comarca groupings, broadly consistent with previously described dialectal affinities associated with neighbouring Granada and Murcia and their dominant varieties, eastern Andalusian and Murcian. This pattern may partly reflect the influence of the Filabres Mountains as a structuring feature affecting interaction and cultural diffusion. In parallel, named bird species revealed a distinct coastal–inland differentiation among comarcas, interpreted primarily in relation to habitat heterogeneity, biodiversity structure and geographic isolation. Coastal areas tended to show higher richness of named species, whereas inland areas exhibited greater linguistic diversity per species, likely associated with ecological heterogeneity, historical connectivity, territorial interaction and processes of cultural transmission and local ecological knowledge. Although causal inference is not possible, the results suggest that dialectal variation may be associated with interacting socio-cultural processes linked to cultural transmission and territorial interaction together with geo-environmental factors related to habitat heterogeneity, biodiversity and geographic isolation. These findings highlight the usefulness of vernacular nomenclature for examining relationships between linguistic variation, territorial interaction, cultural transmission and environmental context. However, the two spatial patterns identified are likely shaped by interacting ecological, socio-cultural and territorial processes whose relative contributions cannot be fully disentangled and therefore warrant further investigation.