Species-specific Accumulation of Microplastics in Different Bird Species from South China: A Comprehensive Analysis

Microplastics are widespread in many bird species, but the inter-specific variations of microplastic contamination are still unclear. The present study measured microplastics in 24 bird species from South China and investigated the impacts of bird physiological and ecological traits on microplastic contamination. The median abundances of microplastics ranged between 5-167.2 particles per individual or 0.023-3.58 particles per g body weight. Approximately 60% of microplastics were within the size range 20-50 μm, with the primary polymer types of polypropylene (PP) and polyethylene terephthalate (PET). There was no significant correlation between microplastic abundances and bird body weights and trophic levels (δ¹⁵N) in different bird species. Insectivorous birds had significantly higher abundances of microplastics smaller than 0.1 mm than granivorous, piscivorous, and carnivorous birds (p < 0.01), which was further supported by the meta-analysis of microplastic contamination in birds. On contrary, meta-analysis results indicate that piscivorous birds tend to accumulate larger microplastics (> 1 mm) than other bird species. Microplastic contamination in different bird species was more influenced by diet source rather than trophic level and body weight. Potential ecotoxicological risks were observed for most insectivorous species in the preliminary risk assessment. Particular concern should be paid on insectivorous birds, which have been scarcely studied for microplastics but were at high exposure risks of microplastics among bird species.