Urban avifauna distribution explained by road noise in an Eastern European city

In Eastern Europe, efforts are being made for road infrastructure development, as this area has not yet reached the level of that in the West. Road noise negatively affects birds, especially in urban habitats. Therefore, seven green spaces from an Eastern European city were monitored, which were selected according to the urbanization gradient and the hydrographic peculiarities of the area. The correlation between species richness and human population density, urban mobility, or road noise was verified. These three factors together explained over 99% of species richness distribution in habitats and during study periods. Road noise was the strongest predictor and the most negative influencer of bird species. These correlations were higher when we also considered the variability of species in habitats over time, instead of the total species richness of a habitat, as it expresses more accurately the impact of noise on the presence of species. The presence of species has decreased from one habitat to another along the urbanization gradient, from the edge of the city to the center, both in the case of terrestrial and aquatic green spaces. The most central park differed significantly from the other terrestrial green spaces in the city. At the same time, no significant differences were registered between the aquatic habitats or the rest of the terrestrial habitats. The ideal mitigation measure in this case would be that there are no roads in the immediate vicinity of green spaces. Still, if this is not possible (as in the case of all the existing green spaces in a city), we discuss/recommend placing noise barriers at the edge of green spaces or high-speed roads.