RESEARCH PAPER Are cities different? Patterns of species richness and beta diversity of urban bird communities and regional species assemblages in Europe Michal Ferenc 1 , Ondr ˇej Sedlác ˇek 1 *, Roman Fuchs 2,3 , Marco Dinetti 4 , Maurizio Fraissinet 5 and David Storch 1,6 1 Department of Ecology, Faculty of Science, Charles University in Prague, Vinic ˇná 7, 12844 Praha 2, Czech Republic, 2 Department of Zoology, Faculty of Science, Charles University in Prague, Vinic ˇná 7, 12844 Praha 2, Czech Republic, 3 Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 C ˇ eské Bude ˇjovice, Czech Republic, 4 Ecologia Urbana, Viale Petrarca 103, 57124 Livorno, Italy, 5 Associazione Studi Ornitologici Italia Meridionale, ASOIM – Via Luca Giordano 12, 80046 San Giorgio a Cremano, Italy, 6 Center for Theoretical Study, Charles University in Prague and Academy of Sciences of the Czech Republic, Jilská 1, 11000 Praha 1, Czech Republic ABSTRACT 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 commu- nities 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 homog- enization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities. Keywords Beta diversity, birds, distance decay of similarity, European cities, homogeni- zation, latitudinal gradient of species richness, species–area relationship, urbanization, variance partitioning. *Correspondence: Ondr ˇej Sedlác ˇek, Department of Ecology, Faculty of Science, Charles University in Prague, Vinic ˇná 7, 12844 Praha 2, Czech Republic. E-mail: zbrd@email.cz Global Ecology and Biogeography, (Global Ecol. Biogeogr.) (2014) 23, 479–489 © 2013 John Wiley & Sons Ltd DOI: 10.1111/geb.12130 http://wileyonlinelibrary.com/journal/geb 479