Effects of light and noise pollution on avian communities of European cities are correlated with the species' diet

Urbanization affects avian community composition in European cities, increasing biotic homogenization. Anthropic pollution (such as light at night and noise) is among the most important drivers shaping bird use in urban areas, where bird species are mainly attracted by urban greenery. In this study, we collected data on 127 breeding bird species at 1349 point counts distributed along a gradient of urbanization in fourteen different European cities. The main aim was to explore the effects of anthropic pollution and city characteristics, on shaping the avian communities, regarding species' diet composition. The green cover of urban areas increased the number of insectivorous and omnivorous bird species, while slightly decreasing the overall diet heterogeneity of the avian communities. The green heterogeneity-a measure of evenness considering the relative coverage of grass, shrubs and trees-was positively correlated with the richness of granivorous, insectivorous, and omnivorous species, increasing the level of diet heterogeneity in the assemblages. Additionally, the effects of light pollution on avian communities were associated with the species' diet. Overall, light pollution negatively affected insectivorous and omnivorous bird species while not affecting granivorous species. The noise pollution, in contrast, was not significantly associated with changes in species assemblages. Our results offer some tips to urban planners, managers, and ecologists, in the challenge of producing more eco-friendly cities for the future.

Automated summary

Urbanization influences avian community composition in European cities by increasing biotic homogenization. Anthropogenic pollution, such as light at night and noise, plays a significant role in shaping bird use in urban areas. Green cover in urban areas attracts insectivorous and omnivorous bird species, but slightly reduces diet heterogeneity in the avian communities. The level of green heterogeneity, which considers the relative coverage of grass, shrubs, and trees, is positively correlated with the richness of granivorous, insectivorous, and omnivorous species, increasing diet heterogeneity in the species assemblages. Light pollution negatively affects insectivorous and omnivorous species, while noise pollution does not significantly impact species assemblages. These findings have implications for urban planners, managers, and ecologists in creating more environmentally-friendly cities in the future.