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Article Tier 2 Environmental Sources Marine & Wildlife Policy & Risk Sign in to save

High microplastic pollution in birds of urban waterbodies revealed by non-invasively collected faecal samples

The Science of The Total Environment 2025 9 citations

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Researchers analyzed bird droppings from urban freshwater habitats in Germany and found microplastic particles, mainly fibers, in 98% of samples across all species studied. The pollution levels were substantially higher than those reported in other freshwater bird studies, likely reflecting the heavy contamination of urban waterways. Since all the investigated species are at least partially migratory, the findings suggest birds may transport microplastics over long distances.

Study Type Environmental

Plastic waste concentrates in aquatic environments, where wildlife can ingest or absorb it. In birds, plastic particles have been identified in hundreds of aquatic and terrestrial species leading to adverse effects. Most studies investigating microplastic pollution in birds use dead individuals or invasive techniques. However, microplastic ingestion can also be determined by analysing birds' faeces. There is a lack of information regarding microplastic pollution of birds inhabiting urban freshwaters, where very high pollution levels are expected. We analysed body condition of individual birds inhabiting freshwaters in the city of Münster (Germany) and microplastic contamination in their faeces. We found microplastic particles (mainly fibres) in all species (Mallard Anas platyrhynchos, Jack Snipe Lymnocryptes minimus, Black-headed Gull Chroicocephalus ridibundus and Common Moorhen Gallinula chloropus) and most samples (98 %). Microplastic pollution ranged from 0.26 to 72.03 particles per mg faeces. The observed microplastic pollution frequency and pollution levels were much higher compared to other studies of birds in freshwater environments, probably resulting from the high contamination of urban waters. We found no effect of the number of microplastic particles on body condition. As all investigated species are at least partially migratory, a long-distance transport of microplastic particles may increase the probability that migratory birds transport (and excrete) microplastic particles to remote locations that otherwise suffer from little anthropogenic pollution. We demonstrate that non-invasively collected faecal samples collected during bird ringing/banding can be used as indicators of microplastic pollution, and call for more studies investigating the effects of microplastics on birds - with a special focus on urban freshwaters.

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