Using feral pigeon (Columba livia) to monitor anthropogenic debris in urban areas: a case study in Taiwan's capital city

<title>Abstract</title> The terrestrial environment is a significant source of anthropogenic debris emissions. While most studies on anthropogenic debris focus on the marine environment, our research delves into human activity's effect on anthropogenic debris ingestion by studying the carcasses of feral pigeons. From January to June 2022, we collected the gastrointestinal tracts (GI tracts) of 46 pigeon carcasses in Taipei, Taiwan's capital city. The results reveal that 224 anthropogenic debris are found, with the dominant form being fibers (71.9%), primarily black (29.9%). Fourier transform infrared spectroscopy (FTIR) shows that the main component of anthropogenic debris is polyethylene (PE) (20.5%), followed by anthropogenic cellulose (19.2%) and various other plastics. This study finds that the number of anthropogenic debris and chemical composition in the GI tract significantly increases with human activity. This result proves that feral pigeons are valuable indicators for monitoring anthropogenic debris pollution in urban ecosystems. On the other hand, past research focused on analyzing microplastic, but we confirmed that pigeons' GI tract has a high proportion of anthropogenic cellulose. It is crucial that future studies consider the potential impacts of anthropogenic cellulose in terrestrial ecosystems, as this could have significant implications for ecosystem health.