Bird community responses to urbanization and vegetation parameters across the city of Salzburg, Austria.

Urbanization continues to be a major threat to biodiversity. The knowledge of local and site characteristics that influence species diversity within cities is of importance to design and manage urban spaces that promote biodiversity and ecosystem services. While the characteristics of urban green spaces for biodiversity have been studied in detail, the urban matrix has received less attention. We, therefore, studied the role of sampling site and local-scale parameters at different urbanization intensities on bird and tree communities during the breeding season across the city of Salzburg encompassing the heterogeneity of the urban landscape. We found more exotic than native tree species, however areas with many trees, were dominated by native tree species. Although building cover negatively related to bird species richness at all scales, bird species richness increased with the amount of grass cover, the number of trees and the number of native tree species at the smallest, i.e. sampling site, scale. Building cover and the number of trees in a sampling site also influenced bird community composition. At larger scales, land cover (i.e., building cover and green urban area) was more strongly related to bird community composition than sampling site characteristics. Relationships with community composition can partly be explained by species-specific responses as the occurrence of different species was associated with different sampling site characteristics. Our study shows the importance of unsealed soil, i.e. grass cover, and native trees on bird communities within cities, but different species may require different configurations of these habitat parameters. Furthermore, also within the urban matrix site characteristics can promote avian diversity even in areas with high building cover. Supplementary Information: The online version contains supplementary material available at 10.1007/s11252-025-01738-y.