From multifamily residences to studio apartments: shifts in burrow structures of European rabbits along a rural‐to‐urban gradient

European rabbits (Oryctolagus cuniculus) are currently declining in most rural areas throughout central Europe, while city populations often reach high densities. We asked whether and how altered environmental conditions affect the social organization and burrow structures of European rabbit populations located at urban, suburban and rural sites in and around Frankfurt a.M. in Germany. Burrow densities (numbers per ha) increased along the rural-to-urban gradient, accompanied by a gradual shift from accumulated towards more evenly distributed burrows. Burrows became smaller and less complex with increasing degree of urbanity, and accordingly, also the number of rabbits inhabiting the same burrow decreased. It remains unclear whether urbanization first led to smaller rabbit group sizes and burrow structures then shifted as a consequence of this, or vice versa. Nevertheless, for both scenarios, we propose that increased structural heterogeneity of urban landscapes is the major factor behind the observed effects, as mosaic-like habitat patches in cities provide high and steady resource availability compared with the agriculturally transformed, open landscapes characterizing most rural areas in central Europe.