Reptiles & Amphibians Non-natives Non-native amphibians Download our new illustrated guide to the alien amphibian and reptile species in the UK! The Midwife toad (Alytes obstetricans) A native of northern Europe, the midwife toad was introduced into a garden in Bedford at the end of the nineteenth century. It thrived and expanded in the locality and further colonies were started in Yorkshire, Worksop and south Devon. In addition, other colonies have arisen from escapees from captivity. The current status of most of these colonies is now unclear but it is safe to say that a number remain in the wild. Fortunately they do not appear to represent a significant competitive or predatorial threat to our native wildlife. This is a small greyish toad, nocturnal in habit and preferring small ponds for breeding. The males have a call similar to a single bell-like tone - thus their other name; the Bell Toad. Their breeding habits are unusual. The spawn string contains a small number of eggs and immediately after fertilisation the male wraps it around his hind limbs and carries it around until the eggs are ready to hatch. It then visits a suitable pool where they hatch and swim away. The tadpoles grow exceptionally large, but the speed of growth is such that they often have to over-winter as tadpoles and metamorphose in the following spring. The Green frogs Marsh frog (Pelophylax ridibundus - formerly Rana ridibunda) Edible frog (Pelophylax esculentus - formerly Rana esculenta) These two frogs form an unusual species complex (which includes our native pool frog (Pelophylax lessonae) due not only to their close relationship but also the results of them inter-breeding. The marsh frog was introduced in the mid thirties on the edge of Romney Marsh. It has since expanded throughout most of the marsh and much of the surrounding countryside in both Kent and Sussex. Other introductions have occurred and it can be found at various locations, throughout southern England in particular. It is the largest and most distinctive of the green frogs. The edible frog is harder to differentiate. It has been introduced, particularly in southern England. It has proved to be particularly successful in East Anglia and south-eastern England. The complex of waterways and ponds in Surrey and the north of Sussex have a clearly growing population. Both species have quite loud calls during the breeding season. This is typically in May, much later than the common frog. The tadpoles grow considerably larger before metamorphosis and on occasion will over-winter and metamorphose early in the following spring. The two species can be told apart by the length of the back leg and the size of the meta-tarsal tubercle - this is a bulge found at the base of the shortest rear toe. The marsh frog has the longest hind leg in proportion to its body with the smallest metatarsal tubercle. The edible frog has shorter hind legs and a larger metatarsal tubercle. The Italian crested newt (Triturus carnifex) This newt is closely related to our own great crested newt (Triturus cristatus) and was, in fact, formerly regarded as a sub-species. This species has appeared in the UK largely as escapees from captive populations. While it is a beautiful animal it does, unfortunately represent a threat to our native species as it shares habitat and the two species readily inter-breed. It is widespread in the south of England but fortunately not common.In appearance it is very similar to the great crested newt, but distinguishing characteristics include very little (often none) white stippling on the flanks, a somewhat smoother skin and the presence of a yellow or reddish vertebral line in juveniles and females. The Alpine newt (Mesotriton alpestris - formerly Triturus alpestris) Another frequent escapee from captivity which seems to thrive in this country. It is of much the same size as our two smaller species of newt and is thus not so easily noticed as the Italian crested newt. It can however be easily identified being very dark, frequently black in colour with a blueish tint. It has a bright red underside and some specimens have a suggestion of a red vertebral stripe. It does not appear to be common in the UK but certainly is widespread. The Bull frog (Lithobates catesbeianus - formerly Rana catesbeiana) This large (up to 25 centimeters long) frog from the United States is the real menace amongst our introduced species. It has a voracious appetite and will eat just about anything smaller than itself. It thus presents a serious threat to much of our wildlife. Apart from its sheer size the call of the males is unmistakable - it is from this call that the frog gets its name. It is found in this country largely as a result of its tadpoles being sold in pet shops. More often than not the frog, once metamorphosed, is deliberately released by thoughtless people, or escapes. It's distribution in the UK is extremely sporadic but it has been known to breed in the wild which is of grave concern. Of all our introduced species this gives most cause for concern and complete eradication from the wild in this country is essential. (find pic) The African clawed toad (Xenopus laevis) This unusual looking largish toad is almost exclusively aquatic. Its presence in this country is due to its use in pregnancy tests. There have been occasional escapes from laboratories on the Isle of Wight & in south Wales. Despite its origin in Africa it is extremely hardy although we have no record of it breeding here. It is a very plump toad, usually a plain greyish or brown in colour and relatively smooth skinned. It's eyes are mounted almost directly on top of its head. It has very hard claws on its hind feet - thus the name. It feeds primarily under water, stirring up the silt and mud at the bottom of pools and streams searching for prey. Again it has a voracious appetite and must be regarded as a threat to many native species. 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.