Anthropogenic nest materials in two distinct populations of migratory bird in Europe.

Abstract Transformation of natural habitats into farming lands and spread of built up areas has a pervasive effect on wildlife, especially for birds. Also, plastic pollution is affecting wildlife on a global scale. Discarded plastic is ubiquitous and accessible for birds, which can be incorporated in the nest structure. By now, a large collection of studies has been published regarding the anthropogenic nest material incorporation by birds. However, studies are predominately biased to marine birds. To balance this disproportion, we describe here the differences in type, prevalence and the amount of anthropogenic nest materials between two populations of terrestrial, mainly farmland bird, the white stork Ciconia ciconia on a broad geographical scale, from two migratory divides – eastern in Poland and western in Spain (in total 303 nests). We detected significant differences in anthropogenic nest material incorporation between two populations in regard to human pressure reflected by Human Footprint Index (HFI) and urbanisation level measured by Impervious Surface Areas (ISA). In Spanish population, we found that probability of anthropogenic nest material incorporation was positively related to ISA, and amount of anthropogenic nest material was positively associated to HFI, in contrast to Polish one, where there was no significant relationship. Moreover, we showed that the prevalence of nests with anthropogenic nest material was two times higher in Spanish than in Polish white stork population. This study demonstrates that the vulnerability to solid waste pollution differs on a population scale within one species.