Dietary shifts driven by invasive plants reshape the gut microbiota of a neotropical thrush

The gut microbiota of wild animals play a crucial role in regulating host health and facilitating adaptation to environmental conditions. While diet is a primary driver of avian gut microbiota, the effects of habitat disturbance and associated dietary shifts on its diversity and composition remain insufficiently understood. In the Mountain Chaco Woodland of central Argentina, large areas have been invaded by alien fleshy‐fruited plants such as Ligustrum lucidum and Pyracantha spp., which fruit during periods of native fruit scarcity, providing frugivorous birds with supplemental resources. To evaluate whether plant invasions influence diet and gut microbiota, we studied the Rufous‐bellied Thrush Turdus rufiventris , a common Neotropical frugivore that readily consumes invasive fruits. We combined faecal analysis and 16S rRNA gene amplicon sequencing to compare diet composition and microbial communities of individuals captured in invaded and non‐invaded habitats during two sampling periods (July and August). Dietary analysis revealed marked differences between habitats: thrushes from native sites consumed higher proportions of arthropods and exclusively native fruits, whereas those from invaded sites relied heavily on invasive fruits. Microbiota alpha‐diversity did not differ between sites or sampling periods; however, beta‐diversity showed significant compositional differences. At the phylum level, Actinobacteria (50.6%) and Proteobacteria (23.3%) were the dominant groups across all samples. In total, 44 phyla were detected, 22 of which had relative abundances > 0.01%. Fourteen of these occurred at non‐invaded sites, whereas 21 occurred at invaded sites, indicating greater phylogenetic diversity in the latter. This study provides novel evidence of the ecological influence of invasive plants as dietary subsidies for native frugivores, with measurable consequences for diet composition and gut microbiota structure.