Adapting to the concrete jungle: Urbanization increases the use of anthropogenic nesting materials by Azure-winged Magpies (Cyanopica cyanus)

Rapid urbanization has resulted in a substantial decrease in natural habitats, posing considerable challenges to bird survival. Bird nests, which are temporary structures used for breeding, reflect adaptation strategies based on their material composition. However, how urban expansion influences the selection of nest materials—particularly the incorporation of anthropogenic nesting materials—remains poorly understood, limiting our understanding of species' adaptive strategies in human-dominated landscapes. To address this knowledge gap, this study examined the nest material characteristics of 432 Azure-winged Magpie (Cyanopica cyanus) nests in Wuhan, Hubei Province, China, to assess the influence of urbanization on nest material selection. Azure-winged Magpies utilized diverse nest materials, mainly branches, moss, soil, polyester fibers, and plastics. Furthermore, nest weight markedly varied among the urban centers, outskirts, and rural areas, with nests in urban centers and outskirts being substantially lighter than those in rural areas. Particularly, the weight of natural nest materials (NNMs) in urban centers and outskirts was considerably lower than that in rural areas, whereas the weight of anthropogenic nesting materials (ANMs) in urban centers did not markedly differ from that in rural areas but was notably higher than that in the outskirts. Across all the three areas, the NNM proportion was substantially higher than that of ANMs. Among ANMs, polyester fibers and plastics constituted relatively high proportions. Furthermore, the weight of ANMs reduced as the distance between the nests and buildings increased. Thus, urbanization may affect the nest material selection of Azure-winged Magpies, showing their behavioral adjustments to urbanization pressures and ecological strategies for using local resources. This study provides a scientific basis for urban biodiversity conservation.