The British Isles are home to six native reptiles, consisting of three snakes and three lizards. There are also at least seven introduced non-native reptiles and a number of sea turtles which are only occasional visitors to the shore. This article covers the six native reptile species.
Common Adder
The Common Adder (scientific name Vipera berus) is the UKs only native venomous snake. They are widespread across the British Isles as well as Europe and even into Asia. Although they are venomous, they are not particularly aggressive by nature, generally only biting when they are provoked.
Did You Know? There are only 14 recorded human deaths from Adder bites in the UK since records began in 1876.
Adders can be found in a range of habitats, essentially in areas inhabited by their prey; which includes birds, amphibians, lizards, and small mammals. They breed between spring and summer, although an adult female won’t breed every single year. The young are born towards the end of the year from autumn and consist of up to 20 youngsters who only remain with their parents for a few days. An adult Adder can grow to a length of up to 90 cm.
Barred Grass Snake
The Barred Grass Snake (scientific name Natrix helvetica) is the most common snake in the British Isles. They can be found across England and Wales, but are not resident in Scotland or Ireland. Grass Snakes are also the only native egg-laying snakes, a female will lay up to 40 eggs in rotting vegetation which hatch in late summer / early autumn. Grass snakes are the largest of our native snakes, growing up to 100 cm in length.
Did You Know? Barred Grass Snakes will sometimes feign death to deter predators from eating them.
Grass Snakes are semi-aquatic reptiles, hunting on land and in the water, and will eat frogs, newts, toads, fish, birds, and even small mammals. Since they are non-venomous, they have to rely on stealth and surprise to catch their prey, often swallowing prey whole while it is still alive.
Smooth Snake
Moving now from the UK’s most common snake to the rarest. The Smooth Snake (scientific name Coronella austriaca) is only present in the Southernmost parts of the British Isles as they prefer warmer climates and heathland environments. Their appearance is somewhat similar to an Adder except they lack the Adders barred pattern on their backs, and their head shape is more streamlined and less angular than an Adder.
The Smooth Snake captures prey by constriction, although unlike true constrictors it doesn’t actually kill its prey by this method. Their preferred diet is smaller animals including birds, amphibians, and lizards. Similar to Adders, they are ovoviviparous, meaning the female hatches eggs internally, but they are born alive. Smooth Snakes are under threat in the UK due to the loss of the heathland environment. Smooth snakes are typically up to 70 centimeters in length.
Slow Worm
Our next reptile is the Slow Worm (scientific name Anguis fragilis). Despite their name and appearance, Slow Worms are not worms or snakes; they are lizards. Their overall body color is a shiny grey-brown, often with thin longitudinal stripes of a darker shade. Older males develop a series of small blue spots. An adult slow worm typically measures around 30 centimeters in length and has a uniformly cylindrical body. It is noted that, unlike snakes, they don’t have a slight narrowing of the body behind the head. Additionally, Slow Worms can be distinguished from snakes by their eyelids, which blink regularly. They also have smooth and shiny scales that give them a polished metallic appearance.
Did You Know? The oldest recorded slow worm was over 50 years old. On average though, they live up to 20 years in the wild.
Slow Worms eat slugs, earthworms, spiders, and various insects. They require two main things in their habitat: access to sunlight and thick vegetation. This adaptability has enabled them to thrive in various environments and consequently can be found across much of the British Isles. Females are ovo-viviparous. This means that the eggs hatch either immediately or shortly after being laid.
Check out our complete species guide on the Slow-Worm if you want to find out more about this species.
Viviparous Lizard
The Viviparous Lizard (scientific name Zootoca vivipara) is also known as the Common Lizard, and as its name suggests; can be found across the majority of the British Isles. They are relatively small in size with an average length between 15 and 20 centimeters. They also range in coloration and can be brown, red, grey, green or black. They can be found in a range of habitats including grasslands, woodlands, moorland and heathland environments. They are terrestrial reptiles spending the majority of their time on the ground. Their diet consists of spiders and flies as well as other insects on an opportunistic basis. As their name suggests, they are viviparous, keeping their eggs inside their bodies and giving birth to live young.
Sand Lizard
The Sand Lizard (scientific name Lacerta agilis) can be found across the European continent, they are however rare in the British Isles and limited to the southern extremes of England. The Sand Lizard assumedly got its name due to its preference to use warm sand to thermoregulate itself and to incubate its eggs. Females lay a single clutch of eggs each year. Despite their name, they can be found in a range of habitats, and spend their time basking in the sun and foraging for food. Adults typically reach a length of 19 centimeters.
