The sand lizard moves downtown - habitat analogues for an endangered species in a metropolitan area

Urbanisation can be dangerous to biological diversity, but on the other hand cities can enhance local and regional biodiversity by providing habitat analogues for many - sometimes endangered - species that are elsewhere excluded from natural habitats. Sand lizards (Lacerta agilis) are endangered in Germany and populations are declining. This species may colonise urban habitats to a certain degree, but the effects of urban development or urbanisation on their distribution and population densities remain unexplained. The aim of this study was to ascertain if the metropolitan area of Berlin offers secondary habitats for sand lizard populations, which environmental factors affect colonisation success and to what degree they tolerate human impacts. In 2012, sand lizard populations in 30 plots (ten urban, ten suburban, ten rural) were assessed regarding their conservation status and environmental variables. We found 15 sand lizard populations; statistical analyses showed no significant differences in individual numbers among the three urbanisation categories. Regression models revealed that the percentage of suitable nesting sites, basking places and suitable microhabitats had a positive effect on density while individual numbers responded negatively to pets and isolation. Urbanisation neither affected sand lizard population densities nor their conservation status, and optimal habitats appeared independent of urbanisation. Urban as well as metropolitan habitats can therefore serve as refuges for this endangered species and negative impacts can be mitigated by forward-looking management, which is characterised by only minimal interventions.