Cornwall Reptile and Amphibian Group: An introduction to the reptiles and amphibians of Britain.

Hello everyone and welcome to our latest blog. Those of you expecting to read about our project on Sand Lizards will notice a change to the schedule. This change is for a great reason though - we are very lucky to have a guest writer ! Matthew Ward has worked with Amphibian Ark - the ex situ ranch of the Amphibian Surveillance Alliance for a long period of time, and has kindly offered to share his wealth of knowledge by providing an overview of the reptile and amphibian wildlife of Britain. We are very grateful for Mathew's help.

In the UK there is a wealth of wildlife for a small island nation, with huge varieties of fauna from terrestrial and aquatic mammal genus’s, avian life and a host of invertebrates species. However when it comes to herpetofauna (reptiles and amphibians) the UK is greatly lacking. In the UK there are around 14 species of herpetofauna (5 frog/toad, 3 snake, 3 newt, 3 lizard). Not all of which are native the isles, species such the Marsh frog Pelophylax ridibundus and its relatives have been introduced but are sometimes thought of as a native.

Herpetofauna can be found throughout the UK but different species are sometimes only found in certain regions or even very specific habitats. For example there are no snakes in Ireland or Northern Ireland and whereas the Common Toad (Bufo bufo) and Common Frog (Rana temporaria) are (as the name suggests) found everywhere although still susceptible and currently under threat of endangerment, the Natterjack (Epidalea calamita) is much rarer only found in acidic, clay based waters. The specific natures and niches of the herpetofauna of this country allow them to make the most of what little the environment has to offer. The two major snake species, the Adder (Vipera berus) and Grass Snake (Natrix natrix) may live in the same regions but partition the habitat. With the Grass Snake favouring frogs, fish, bird eggs and small mammals in the fields, grasslands and riverine habitats whilst the adders are more often found in heathfields, woodlands and more rural areas feeding on invertebrates, small mammals and other reptiles. Both species are competent swimmers, both need to bask in sunlight and warmth to become active and with the similar prey availability the only way to survive together is to occupy different habitat areas.

Snakes

The UK is host to 3 species of snake, the Adder, Grass Snake and Smooth Snake (Coronella austriaca). The largest being the Grass snake, also the most common, reaching lengths of almost 1m. Grass snakes are distinguished by their green/olive colour with a black head separated from the body by an orange/dark red collar. The Adder is a lot shorter reaching around 20-30cmfor males and around 50-80cm for females. Very recognisable as a viper with their wide triangular head housing the venom glands and their distinctive black diamond/zig zag patterning down the dorsum. Colour is dimorphic with males predominantly white/pale sliver/ grey and the females a much darker brown/rustic green. The final snake is the smooth snake, a much rarer sight in the UK with very specific habitat types and locations of sand dunes and heathlands in the far south of England. To identify them the body is similar to that of the grass snake (slender small headed) but the colour is dark browns/greys on the dorsum and a brighter yellow/purple underside. Whilst none of these snakes are dangerous they can still bite and shouldn’t be handled by anyone not experienced, the adder IS still venomous and whilst not a deadly venom it can still cause an allergic reaction in some cases. For the sake of the animal as much as the person the behaviour is always to be noted, this is how they will tell you when you are going too far.

Smooth Snake: http://www.herpetofauna.co.uk/ident_images/ca1.jpg

Lizards

There are also 3 species of lizard in the UK with the Common Lizard (Lacerta vivipara), Sand Lizard (Lacerta agilis) and the Slow Worm (Anguis fragilis). The Common Lizard and Slow Worms are both widespread across the nation in many grasslands, heathfields and areas with large rocky outcrops where they will bask. Both species predominantly feed on invertebrates with the Slow Worms even being quite common sites in urban gardens eating the ants and mites living in compost heaps and flower beds. The Slow Worm is a species of legless lizard and also the largest of the lizard species reaching over 50cm in length and reaching a whopping 40+ years in longevity, as a reptile it is much longer lived than its avian or mammalian equivalent. The Sand Lizard, similar to the smooth snake, is much rarer with a specific habitat type required particularly sand dunes and sand/grass field. Its hotspots are Merseyside and Dorset but as they are an endangered species and are protected it is advisable not to get too close or attempt to handle this species.

Slow Worm http://www.wildlifeinsight.com/Insight/wp-content/gallery/gb_reptiles/slow_worm_5721.jpg

Anura

Anura is the amphibian group containing frogs and toads and in the UK it consists of the Common Frog, Common Toad, Natterjack toad and Green Frogs (marsh frogs and their relatives). The differences between frogs and toads are numerous but the easy ones to use are the skin (smooth=frog, lumpy=toad) and the eggs/spawn (cluster=frog, lines=toad). Both sets of eggs hatch in tadpoles and go through the same metamorphosis process to become adults.

The Common Frog is a large frog with adult females reaching occasionally 12cm (body length, SV length). They are found all over the country favouring ponds with plenty of invertebrate prey and hiding places from predatory birds. The best time to see any of these amphibians is at night where flashlighting (using a torch) is good at spotting them in the water and still considered the best way to measure populations. You may also be able to see them out of the water then as the temperature and moisture of the grass would allow them to forage at the ponds edge.

The Common Toad is slightly smaller than its common frog cousin with a rounder head. The frog is generally green-brown with black eye patches but the toad is usually a dull brown with the drier, bumpy skin. They are more active on land than the frogs and prefer deeper ponds for breeding but will still inhabit the same ponds with overlapping home ranges. The natterjack gets its name from it mating call which is a loud rasping call with much less gap between each ‘croak’ than other anura. It’s smaller than the common toad with olive skin and a yellow line running down the spine. It’s much rarer only found in some areas around the UK including reintroduced on the Welsh north coast, more often found in sand dunes and saltmarshes. Under threat from human encroachment and previously extinct in the Wales.

Marsh frogs and the other green frogs are still debated over as to whether they are native, they have now however been given protection by British law. They look similar to common frogs with green/brown colouration but slightly larger body in some subspecies, they are usually spotted or striped and lack the black eye patches of the Common Frogs. Whilst they are called common, all of these amphibians have been declining in number due to habitat loss, invasive fish species and human encroachment. Habitat loss for an amphibian can be a lot less extreme than a lost forest. The loss of a certain aquatic plant or invertebrate can devastate the population or a slight change in temperature and pH.

Illustration of Common Frog http://www.rspb.org.uk/Images/common_frog_180_tcm9-60284.jpg

Newts

There are also three newts in the UK in the Great Crested Newt (Triturus cristatus), Smooth Newt (Lissotriton vulgaris) and the Palmate Newt (Lissotriton helveticus). The Great Crested Newt is the largest and given the name in the breeding season the males have a large dorsal crest that goes along the entire body and tail. The body is a dark green/black with a vivid yellow and orange belly. The underside is patterned with black spots that are as unique as a fingerprint, this has great implications for conservation as the identification of individuals can be done with a record of the underside. This species is a burden for construction because they are protected as a European endangered species and require very specific pond types. One of the reasons for their declines over the years is the damage to their breeding ponds. The Palmate Newts and Smooth Newts are smaller without the great crests and have less specific breeding requirements. They are a similar dark green/black colour with the only differences being they colour of the underside (pink=smooth, yellow=palmate) and in males the Palmate Newt has black toes and a small black filament on the end of the tail. These two species have also been noticed to hybridise and will regularly share ponds. They are generally common around the country in large ponds, small ponds and gardens and eggs would generally be deposited on leaves under the water’s surface.