Urban trace metal contamination is negatively associated with condition and wing morphology in a common waterbird

Urban areas suffer from different forms of environmental pollution by light, noise, and chemicals. Pollution by trace metals has long been associated with industrialization and urbanization processes, increasing the risk of bioaccumulation and compromising the health, condition, and fitness of urban animals. Here, we aimed to investigate the effects of urbanization on bioaccumulation of six trace metals (Cu, Ni, Zn, Cd, Pb, and Mn) in the integumentary structures (feathers) of a non-passerine waterbird, the Eurasian coot (Fulica atra). For this purpose, we quantified and compared trace metal concentrations in feathers of 300 coots from four pairs of non-urban and urban populations associated with major agglomerations in Poland. We found that concentrations of three trace metals (Cu, Ni, and Zn) were significantly higher in coots from the urban landscape, compared to individuals from natural or semi-natural non-urban habitats. Elevated trace metal concentrations were negatively associated with morphology (wing length) and condition (body mass and blood haemoglobin concentration) of coots, and these associations were detected exclusively in the urban landscape. There was limited evidence of elevated trace metal pollution in the non-urban landscape (only Cd) and only weak support for a negative association of Pb concentration with physiological stress of non-urban coots. Our results suggest that trace metal contamination may be considered an important cost of urbanization processes in wildlife. We argue that mitigation of trace metal pollution in urban ecosystems should likely increase their sustainability and viability of urban animal populations.