The wall lizards are closely related to our native viviparous lizard, which they superficially rather resemble. They belong to a genus called Podarcis which contains approximately 21 species, although the exact number depends on whose taxonomy you accept! The genus is widely distributed across Europe, but none are native to the UK; at least not to the mainland, although one species is found living on the Channel Islands.
As their name suggests wall lizards live on and around old walls or cliffs, scuttling rapidly up and down the vertical surfaces and retreating into gaps and crevices for shelter.
Wall lizards have long been popular in the pet trade and consequently have either escaped or been released into various parts of the UK where some seem to have found an available niche and have secured a foothold.
Here in Somerset there are two small populations, one in Wellington and another in Wembdon, both belonging to the species Podarcis muralis, the common wall lizard.
Of all the species of Podarcis, this is perhaps the one that might find it easiest to establish itself here, given the chance. It is the species that has the widest natural distribution of all those in its genus, reaching from the eastern Mediterranean to the shores of northern France, suggesting a highly adaptable creature. It is also the species that is native on the Channel Islands, so it can easily acclimatise here.
In some parts of the country where these lizards have become established, they are believed to have a detrimental impact on native lizards. However, to date the two small populations found in Somerset have not spread out from the sites where they were originally discovered and do not appear to be having any obvious impact on the local ecology either detrimental or otherwise.