The use of plastic litter as nesting material by the azure-winged magpie Cyanopica cyanus in an agricultural environment of South Korea

In bird species, anthropogenic nesting materials have been known to have a negative effect on the survival of birds in general, but in some species, these can be used instead of natural materials, which can have a positive effect on the structural aspects of nests. Our study aims to investigate the type and amount of anthropogenic materials found in the nests of the colonial breeding azure-winged magpie ( Cyanopica cyanus ) in an agricultural area, as well as the characteristics of these used for each nest structure. We found that plastic litter was used in all of the azure-winged magpie breeding nests observed, and the types and amounts of plastic litter used differed between the cup and the outer. In all nests, soft, elastic, and insulating materials such as polyester fiber were mainly observed in the cup, and strings that weave and anchor branches and soil from nature were mostly found in the outer. The amount of plastic litter used in nests was related to the size of the nest. Plastic litter used in nests is thought to be collected from agricultural materials used in agricultural lands, vinyl greenhouses, and agricultural warehouses in our study site. Consequently, we expect that the phenomenon of azure-winged magpies using plastic litters for nest building may be common situation for the current agricultural environment where plastics are widespread.