A cultural interest index based on vernacular names: exploring trait-dependent patterns in birds

A new Cultural Interest Index of Species (CIIS) is proposed to quantify species’ cultural salience from vernacular nomenclature and folklore. Unlike approaches requiring informant-level citation frequencies, the index can be applied to existing lexical inventories while integrating multiple dimensions of cultural expression. This study develops the CIIS and evaluates whether variation in the index is associated with biological and perceptual traits of species. The CIIS was constructed from four normalised components—vernacular diversity, territorial distribution, etymological diversity and folkloric use—and weighted using a hybrid framework combining entropy and CRITIC methods. The index was applied to 264 bird species regularly occurring in the province of Almería (southeastern Spain) using a dataset comprising 1,001 vernacular names and 117 folkloric uses compiled from 541 information sources, including 519 informants and 22 published sources. Associations between CIIS and species traits were evaluated using correlation analyses, multiple regression models, and phylogenetic generalized least squares (PGLS) following assessment of phylogenetic signal with Pagel’s λ across 100 alternative avian phylogenies based on the Hackett backbone. CIIS exhibited a moderate and consistently significant phylogenetic signal. Nevertheless, the principal trait associations remained robust after phylogenetic correction. In the complete-data model, European population size, acoustic diversity and body chromatic intensity were positively associated with CIIS and remained significant across all 100 phylogenetic trees. Population size also remained significant in the larger reduced dataset. Results were highly consistent among the objective-weighted, heuristic-weighted and equally weighted formulations of the index. Passerines exhibited higher CIIS values than non-passerines, whereas the apparent association with conservation status disappeared after accounting for taxonomic group. No significant relationship was detected between ecosystem services and CIIS. The CIIS provides a flexible framework for quantifying cultural interest across taxa, regions and cultural contexts using nomenclatural and folkloric information commonly available in existing sources. Although broader validation requires independent applications, the persistence of the principal associations after phylogenetic correction indicates that they are not attributable solely to shared evolutionary history. The CIIS may therefore support comparative research on cultural salience and help identify patterns relevant to biodiversity conservation, communication and prioritisation.