Reptiles & Amphibians Non-natives Non-native reptiles Download our new illustrated guide to the alien amphibian and reptile species in the UK! On the UK Mainland one particular species of European lizard has gained a firm foothold. While we know some populations have been introduced, the origin of others is uncertain. It may, indeed, be native in some areas. This is the wall lizard. One further lizard species, the green lizard, is most unlikely to be native although there have been repeated introduction attempts in the past (now, of course, illegal), many of which have survived for a great many years. There is certainly one current breeding colony known in the south of England. Both of these species are native to Jersey in the Channel Islands. Wall lizard (Podarcis muralis) The wall lizard can grow to about 20cms in total length, up to two-thirds of which might be tail. It is a little larger than the viviparous lizard. Pattern and markings are very variable but can be very similar to the viviparous lizard's. It can also be differentiated from the latter species by its rather pointed head as against the bullet-shaped head of the latter. Both male and female can often be coloured quite a bright green - not to be confused with the occasional green tint in the viviparous lizard. The Green lizard (Lacerta bilineata - formerly Lacerta viridis) This is far and away the largest lizard you are likely to see in this country. It can reach a total length in excess of 35cms. It is another bulky lizard rather like the sand lizard in build but unlikely to be confused with this or any other species because of its size and the overall green colouration. Some females and juveniles have two noticeable white lines on each side of the back and in the latter case, the base colour is brown rather than green. Mature males often develop blue cheeks during the breeding season. Although the adult animals appear to have no difficulty in surviving in our climate, historically the summers have not been good enough to allow egg incubation over sufficient years to allow colonies to become truly established. With global warming this situation is changing and we certainly have at least one population which has now been established and growing over a number of years. The Aesculapian snake (Zamenis longissimus - formerly Elaphe longissima) A colony of unknown origin occurs in and around the grounds of the Welsh Mountain Zoo in Colwyn Bay, north Wales, and has existed there for 30-40 years. Numbers are unknown, but the colony is likely to contain at least several dozen individuals. Reproduction appears to occur regularly, as specimens of all size classes can be found, but at present, there is no indication that the species has spread beyond the immediate vicinity of the zoo. Adults are unmistakable, being more or less uniformly olive or brownish, often with light stipples on some scales. Juveniles can be confused with juvenile grass snakes. However, they differ in having a well-defined dark stripe from the eye backwards along the sides of the head, which is not present in grass snakes, and in lacking dark edges to most upper lip scales, which are conspicuous in grass snakes. The European pond terrapin (Emys orbicularis) This terrapin used to be native c. 8,000 years ago. It was presumed to have become extinct due to climate deterioration. However, odd individuals have been found in this country in recent years although we are uncertain if they are breeding. It can only be conjectured whether these constitute a remnant of the original population or are escapees from captivity. The Red-eared slider (Trachemys scripta elegans) The Red-eared slider is another terrapin species which has become distressingly common in the wild in the UK. It is not however, native, originating from North America. All the individuals in the wild in the UK are the result of escapes or deliberate releases. There is some suggestion that they may represent a threat to wildfowl chicks and fish but there is little evidence to substantiate this. Priorities for Non-Native Amphibians and Reptiles in the UK:- This short report is a simple summary of the introduced amphibians and reptiles now known to be found in the UK, as well as a subjective indication of priorities in terms of “concern” and research.