First record of meso- and microplastics ingestion in hummingbirds (Trochilidae)

Abstract

Plastic fragmentation represents a risk for ecosystems. Hummingbirds (Trochilidae) are nectarivorous birds restricted to the Americas, where they fulfill critical ecosystem roles as pollinators. The aim of this study was to assess the occurrence of meso- and microplastics (MMPs) in the gastrointestinal tract (GIT) of three hummingbird species from the floodplain of the Middle Paraná River (Argentina). Necropsies were conducted to extract the stomach and intestine, which were chemically digested. All particles were counted and classified by morphology, size and color, while a representative sub-sample of fibers (n = 32) and all fragments and films were selected for FTIR characterization. A total of 237 particles were visually identified and grouped by morphology into 228 microfibers, 5 mesofibers, 3 fragments and 1 film. Size fractions between 0.063 and 2 mm accounted for 82.28% of the total of particles. Of the 36 particles chemically characterized by FTIR, 14 were confirmed as synthetic plastic polymers. Two fragments were identified as polyurethane, one as polyamide, and the only film as polyamide, while polyester (n = 6, 19%) and polypropylene (n = 4, 12%) were identified in fibers. The remaining 22 particles, all fibers, were identified as cellulose of uncertain origin (69% of the analyzed fibers). Abundance ranged from 8 to 36 particles/bird. No statistically significant differences were detected among the three species (n_Cl = 5, n_Hf = 2, n_Hc = 4). Multiple potential ingestion routes for MMPs in nectarivorous birds were proposed, including potentially contaminated nectar, pollen, water, and insect prey. These findings highlight a potential exposure concern for hummingbirds that requires further investigation.