Biomonitoring of Heavy Metals Using Feathers of Different Bird Species in Mashhad Metropolis, Iran

In the present study, thirteen urban bird species were used as bioindicators to monitor metal concentrations in the metropolis of Mashhad. The concentrations of lead (Pb), zinc (Zn), and copper (Cu) ranged from 0.004 to 0.073, 0.750 to 1.400, and 0.502 to 1.202 µg/g dry w, respectively. The lowest concentration of Pb was observed in Corvus corax and Corvus frugilegus species, while the highest concentration was found in Turdus iliacus. The lowest concentration of Zn was in C. frugilegus, and the highest concentration was in Spilopelia senegalensis. The lowest concentration of Cu was in Galerida cristata, with the highest concentration in S. senegalensis. The results revealed statistically significant differences in the concentrations of the studied elements in some species. Although the values of the studied elements were higher in the Insectivore and then Granivorous groups compared to the Carnivore and Omnivore groups, there was no significant difference between species based on their diet. Additionally, there was no statistically significant difference in element concentrations between adult and immature samples, as well as between small-bodied and large-bodied samples. Risk assessment of element exposure showed that the concentrations in all thirteen species' samples were below the permissible limits, indicating a low health risk from metal exposure for these species. It is worth noting that this research marks the first global measurement of metal values in Spinus spinus, T. iliacus, and Phoenicurus erythronotus species.