Aim
To compare macroecological patterns between bird communities of European cities and regional species assemblages in the surrounding landscape, and to reveal geographical trends in the urbanization of native avifauna.
Location
Forty‐one towns and cities in continental Europe.
Methods
We compiled data on the species richness and community composition of urban avifauna from 41 European city breeding bird atlases, and of species assemblages comprising nine grid cells (each about 50 km × 50 km) from the EBCC Atlas of European Breeding Birds (hereafter regional assemblages). Species–area relationships (SARs), latitudinal trends in diversity and the distance decay of community similarity were compared using regression models (generalized linear models). Observed urban communities were compared with randomly assembled ones to reveal systematic effects of the urban environment on native bird communities across Europe. We employed variance partitioning to quantify the relative effect of environmental parameters and the spatial position of cities on species richness.
Results
The species–area relationships did not differ significantly between cities and regional assemblages. Species richness of both types of communities increased towards higher latitudes, although the relationship was unimodal for regional assemblages, in contrast to cities. The increase in beta diversity with distance was on average less pronounced in cities than in regional assemblages, and was lower between individual cities than between communities of the same size randomly drawn from regional species assemblages. Moreover, average beta diversity was lower in northern cities, which are characterized by a relatively higher proportion of species from regional species pools.
Main conclusions
The species–area relationship and latitudinal trends are largely congruent between cities and the regional assemblages. However, city avifaunas tend to be relatively more uniform across space, revealing biotic homogenization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities.
Context
Urbanization and its associated impacts on biodiversity are increasing globally. There is a need to enhance our understanding of species responses to inform strategies for sustainable urbanization.
Objectives
Three extensive bird monitoring campaigns took place over the last three decades in the city of Naples, Italy, providing a comprehensive longitudinal dataset to analyse occurrence trends of urban birds. We aimed to assess both species-specific and assemblage-level changes in urban birds according to land cover dynamics.
Methods
We extracted bird data for the periods 1990–95, 2000–05, and 2014–18, and explored the spatial and temporal relationships between bird presence/avian assemblage composition, and land cover variation.
Results
The species richness of breeding birds remained stable over time, despite a notable species turnover, influenced by changes in the species’ key land cover classes. Species associated with forest and urban land cover tended to colonise the area, while those dependent on abandoned and cultivated areas decreased or went locally extinct. Birds changed their degree of dependence upon their key habitat type over time, as species from marginal and open habitat types needed larger amounts of habitat to persist within the area, while forest species showed an opposite trend.
Conclusions
Habitat-driven changes in avian assemblages within the urban landscape led to an increase in forest-associated species, and a decrease in birds associated with declining habitat types. Our findings may inform urban planning to promote more wildlife-friendly cities, which for our study area should prioritise open and marginal habitats.
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