Individual variation of arthropod content in the diet of Hyacinth Visorbearer (Augastes scutatus), a restricted-range Neotropical hummingbird

Arthropods represent a critical food source for birds, including non-insectivorous species. While previous studies have documented arthropod consumption by hummingbirds, none have assessed individual-level variation in arthropod dietary composition and preferences. For example, in the Hyacinth Visorbearer (Augastes scutatus), a Neotropical hummingbird with a restricted range, only a single study has reported arthropod ingestion. In this study, we quantified arthropod composition in the diet of A. scutatus and evaluated individual foraging preferences. Using specimens collected across the species’ distribution, we analyzed stomach contents (n = 25) and identified 292 food items categorized into eight taxonomic groups. Hymenoptera dominated the diet, accounting for nearly 75% of all items. By decomposing β-diversity, we demonstrated that dietary differences among individuals were primarily driven by turnover (incidence- and abundance-based β-diversity). This high replacement of secondary food items likely reflects a strong trophic preference for highly mobile insects (e.g., strong fliers). Our results reveal that most individuals exhibit a specialized diet, characterized by consistent consumption of a few primary items (mainly Hymenoptera and Diptera), while secondary items vary widely in identity and quantity.