Tracking the origin and current distribution of wall lizards (Podarcis spp.) in Poland

Among the most successful European reptilian invaders are lizards of the genus Podarcis. Human activities have facilitated the spread of these lizards beyond their native range, often establishing thriving populations in new locations. Poland lies beyond the northern range of all Podarcis species, but between 2011 and 2014, three populations representing the Central Balkan clade of P. muralis were discovered in the Strzelin Hills (SW Poland). Our aim was to determine the current distribution and introduction routes of Podarcis lizards into Poland. We searched for P. muralis in 44 additional localities (with conditions known to be preferred by the species in Central Europe, such as ruins of abandoned buildings, railway stations, and quarries) in the Strzelin Hills as well as surveyed literature sources and online platforms to identify cases of introduction of Podarcis lizards into Poland. No new sites with P. muralis have been discovered in the Strzelin Hills and the occurrence of the species in this area is limited to three already known sites. Nine cases of the introduction of wall lizards were confirmed. These ranged from single individuals of P. muralis or P. siculus introduced via freight transport and captured immediately after, to two introductions of P. muralis that resulted in the establishment of populations that persisted for at least several years. Molecular analyses showed that the introduced lizards originated from several ‘exotic’ lineages (i.e., not the Central Balkan clade) from Italy and Croatia, although secondary introductions are possible. Given the ability of southern lineages to establish viable populations in Poland, continued monitoring is essential.