Risks and Opportunities of Urbanization ? Structure of Two Populations of the Balkan Wall Lizard Podarcis tauricus (Pallas, 1814) in the City of Plovdiv

The current study analyzes the structure and some features of two urban metapopulations of the Balkan Wall Lizard (Podarcis tauricus (Pallas, 1814)) from Nature Monument (NM) “Mladezhki halm” and Nature Monument “Halm na osvoboditelite” in the city of Plovdiv (South Bulgaria). In both study sites, the Balkan Wall lizard inhabits exclusively the interior of the hills and prefers mainly open areas with rare grass and shrub vegetation. The recorded dominant plant species are not autochthonous for the hills, but gradually displaced with many decorative species, used widely in the gardening and the city parks. The population abundance from both hills is relatively low, with higher values in NM “Mladezhki halm” and generally shows a decrease pattern for the two year period. In the hills of Plovdiv, the Balkan Wall lizard shows a bimodal diurnal and seasonal activity. Both metapopulations showed a sex ratio close to 1:1 with a slight superiority of the females (1:1.29), but with no statistically significant deviation. The age structure of both metapopulations is almost identical - the highest percentage takes the adults, followed by the subadults and juveniles, with no significant deviations from the normal ratio. The possible reasons for the contemporary distribution and population structure of the Balkan Wall lizard are discussed. Historic land use change and its effect on the populations are discussed as well. The main risks for this species in the city of Plovdiv are construction and forestation (destruction of open terrains). Nevertheless, the Balkan Wall lizard seems to have successfully overcome the risks of urbanization and its population seem stable and sustainable.