The New Forest is one of the few places in the UK that is home to our six native reptiles, including the two rarest – the Smooth Snake and Sand Lizard. Heathland destruction in other parts of the country means that the New Forest has become an important haven for them and all six species can be seen at the New Forest Reptile Centre.
Reptiles are cold-blooded creatures who obtain their body heat directly from their environment. Most of them like to bask in warm, dry areas with good surrounding cover so that they can escape if a predator (or human) approaches. Open Forest areas with sandy soils that heat up quickly are the best habitats for them and this makes the New Forest with its heathlands an ideal area. In particular, adders can often be seen on the side of gravel tracks which are exposed to the sun as they bring their bodies up to temperature.
All British reptiles are protected by law under the Wildlife and Countryside Act 1981, and it is an offence to kill, injure or trade any of them.
ADDERS (Vipera berus)
The adder (sometimes known as the common viper) is the most common snake on the Forest where the open tracts of heathland and woodland edges provide an ideal habitat. The adder is the UK’s only venomous snake although is quite timid by nature and generally only bites as a last resort when it feels threatened. Very occasionally their bites can be life threatening but to put it into perspective, in Britain there have been only 14 known fatalities since 1876. However, medical attention should always be sought in the case of a bite.
Adders are variable in colour. Males are generally a silver grey, whitish or occasionally yellowish in colour which contrast sharply with their black markings down their back. The females tend to be olive or brownish with considerable variation of shade and are always a much darker shade than the males. Both sexes have similar markings on the head and along the back. These markings are very pronounced making it easy to identify an adder. There is a heavy dark zigzag diamond pattern down the back with dark spots in rows on the flanks. At the back of the head there is a heavy “V” or “X” shaped marking and a dark band running from behind each eye. Occasionally both male and female adders can be found that are almost totally black in colour (melanistic). Females are larger than males – males grow up to 60 cm and females up to 75 cm.
Adders generally hibernate from late September onwards. Their hibernacula (hibernation sites) are usually located within sunny, south-facing slopes or embankments, on well-drained soils. Adders emerge from hibernacula to bask on sunny days, in March or April, in preparation for mating. Shortly after they emerge they shed their skins to reveal their colours at their vivid best.
The adder does not feed until after it has mated when both the male and female adder live off their fat reserves. Once a male has found a receptive female they will defend her against other males – these fights are known as the “dance of the adders” as the males raise their head and upper bodies off the ground often entwining heads and repeatedly falling to the ground and rising up again. The mating period varies, depending upon annual weather conditions, but usually the last two weeks of April or the first week of May. The young are born in late August/early September. Unlike most reptiles, adders do not lay eggs and their young are born about the size and shape of an earthworm – a perfect miniature of the adult snake. In their early stages young are coloured much like adult females. Immature adders are often threatened by a variety of predators, including birds of prey and sometimes adult snakes.
Adders usually eat small rodents but will also eat lizards, frogs and newts. When searching for their prey, adders strike swiftly injecting a lethal dose of venom. Like all snakes, adders eat their prey whole and their jaws are linked by extendable tissue which enables them to swallow items much larger than the width of their head.
During the autumn, adult snakes follow scent trails left by other adders to find their way back to their hibernation sites, which are often used over several years. Young adders tend to hibernate in the area near where they were born. Their survival over the winter largely depends on the severity of the weather and some may be killed and eaten by rodents while they are hibernating. The life span of the adder is up to 15 years.
GRASS SNAKE (Natrix natrix)
While not as common as adders in the New Forest, the grass snake is Britain’s largest terrestrial reptile. Unlike the adder, it is not venomous and its only defence is to produce a foul smelling liquid from the anal glands usually accompanied by a loud hissing sound. It will also feign death by exposing its underbelly, becoming completely limp. They may also give an aggressive display to defend themselves by hissing and striking without actually opening the mouth. They rarely bite.
Colouration is typically olive-green, brown or greyish in colour with a row of black bars on its sides. The underside of the grass snake is off-white or yellowish with dark triangular or rectangular markings. A characteristic and distinctive black and yellow collar is present behind the head. Totally black (melanistic) forms are occasionally found. It is difficult to distinguish the sex of a grass snake but females grow larger than the males and often reach over a metre in length.
It is fast moving and wary of humans which makes it difficult to spot. They favour damp rough land and pastures, usually close to a standing body of water. They are good swimmers, able to stay submerged for up to an hour and feed almost exclusively on amphibians although some may take small fish. During winter they find frost-free places such as deep leaf litter or rock piles in which to hibernate between October and March or April.
Mating takes place from March to June. The male grass snake will curl its body around a receptive female, rubbing the female with his head and wrapping his tail closely around the females body. After mating the female searches for a nest site. The grass snake is Britain’s only egg laying snake and the eggs are laid in compost or manure heaps where the rotting vegetation provides warmth. The leathery white eggs usually hatch six to eight weeks after egg-laying. The male grass snake reaches maturity at 3 years of age, but females do not begin to breed until their fourth or fifth year. Mature males shed their skin twice a year, whereas females only shed their skin once a year just before egg-laying.
Grass snakes are predated upon by badgers, foxes, domestic cats, hedgehogs and a number of large birds. They can live for up to 15 years.
SMOOTH SNAKE (Coronella austriaca)
This snake is very rare in the UK and can only be found in a few places, often alongside other rare reptiles like the sand lizard because they both favour the same kind of sandy heathland habitat such as the New Forest provides. It is confined to sandy heaths in Dorset, Hampshire and Surrey and reintroduced populations in West Sussex and Devon.
Smooth snakes are similar in appearance to the adder, but can be distinguished by a number of features including a rounder head and a slimmer body up to 60cm in length. It is brown or grey in colour and has dark spots on the upper surface rather than the zig-zag patterning characteristic of the adder. The eye has a round golden iris and the head is brown with a black crown and eye stripes. Females are slightly larger than males and are usually uniform silver grey, with distinct spots. Males tend towards browns and reds with their spots being less marked. In both sexes the eye has a round golden iris.
It is an extremely secretive snake, spending much of its time in a variety of crevices and holes in the ground, under stones, in loose sand and soil or concealed in litter and vegetation. They are non-venomous and totally harmless to humans. Their diet consists of lizards, small mammals, and snakes (including other smooth snakes), which are caught by a quick strike and subdued by being squeezed in coils of the body. Prey is then swallowed whilst alive.
Information regarding breeding is sketchy and it is thought that they only breed every other year unless conditions are very favourable. Mating occurs in April, May and early June. Similar to the adder, eggs are produced but the young hatch out of these internally and between 4 and 15 live young are born in September or October. The young snakes may hibernate immediately after birth, emerging the following year usually in March. Hibernation sites are usually underground in dry frost-free shelters that are safe from predation – disused mammal burrows are often used.
They can live for up to 20 years. In the UK, habitat destruction is a serious threat to this species. For many years, lowland heaths have been lost to make way for the house building resulting in smooth snakes are dying out in these areas. Additional dangers come from areas where residential housing is situated near heathland, as the snakes are vulnerable to attacks by domestic cats. They are also predated upon by birds of prey.
SLOW WORM (Anguis fragilis)
Despite looking very much like small snakes, slow worms are in fact legless lizards. As with the other lizards, slow worms have eyelids and are able to blink and to close their eyes when resting unlike snakes who have no eyelids. They are also characterised by an almost complete absence of markings on the body, although some females are found with a thin dark stripe along the back. Slow worms vary in colour, from a bright coppery brown to a leaden grey. Females tend to be brownish, while the males are usually more grey and both are quite shiny in appearance. Their habitat is usually among long dry grass or in soft soil and undergrowth, usually with somewhere nearby where they can sun themselves. They are almost always underneath a rock or discarded sheet metal. When old corrugated iron sheets are left beside buildings, slow worms sometimes take up residence there, and they will also hibernate in such places. They are also commonly encountered in compost heaps. They spend the winter hibernating under piles of leaves or within tree roots.
They are non venomous and completely harmless and their diet comprises mainly of slugs, snails, spiders, insects and earthworms and should be regarded as a welcome visitor to any garden. If attacked by a predator, they can shed the tip of their tail to escape, although it never grows back completely.
They emerge from hibernation in March, when it may be seen basking in the early morning and evening sun, as the animals come into condition for breeding, which occurs in May. During courtship, the male takes hold of the female by biting her head or neck, and they intertwine their bodies. The young take 4 to 5 months to develop, being produced in late August to early September. Like the adder and smooth snake the young are born in an egg membrane inside the body and they emerge as miniature editions of their parents. Between 3 and 26 young can be produced but the average is 8. New born slow worms appear remarkably small, being under a centimetre in length at birth, giving the appearance of an earthworm. After several years they grow to length of 40/50 centimetres.
They are relatively long lived and can live to 30 years in the wild. They suffer predation from birds, snakes and mammals, particularly domestic cats.
COMMON LIZARD (Zootoca vivipara)
Common lizards’ upper body colour is variable and can be grey, reddish or dark green as well as the usual dark brown colour, with patterns of lighter or darker brown lines running the length of the body. Their scales gives the skin a slightly beaded texture and appearance. The legs are relatively short and stocky, with five tapering toes on each foot, and a long tapering tail that makes up about two-thirds of the total length. Common lizards are quite variable in size and adults usually grow to 13-15cm in total length although males can grow up to 20cm.
The common lizard is widespread across the UK. They prefer habitats where there is a mixture of vegetation cover and open areas, such as heathland, dune, scrub, woodland edge and abandoned industrial land. They can also be found in relatively damp habitats as they are good swimmers. On a warm sunny day they can sometimes be seen on the edges of Forest tracks that provide them with basking spots, just clear of the vegetation.
Common lizards are very agile, fast-moving creatures which allows them to catch their prey which comprises mainly of small insects. Once these lizards have reached their optimum operating temperature they move along regular routes in search of prey which is seized in the jaws, shaken to stun it, if necessary, and swallowed whole. Common lizards are vulnerable to a range of predators including domestic cats, foxes, crows, jays and hawks as well as other reptiles. Their agility helps them avoid predators but in extreme circumstances they will also shed their tails, leaving a wriggling tail to distract the predator while the lizard escapes. Its average lifespan is 5 to 6 years.
Like other reptiles, they hibernate over the winter from October to March and after they emerge, courtship and mating begin within a few weeks when male body colours are at their most vivid after shedding their skins. Some fights occur between the males at this stage but it is the females who usually seek out the males when they are ready to mate. Males seize the female in their jaws and the process usually lasts a few minutes. Females usually mate more than once either with the same male or with several. Development of the eggs takes 3 months during which the females bask for long periods to maintain high growth rates. They normally give birth in July to between 3 and 11 offspring, the average clutch size being 7 or 8. Young are born in transparent membranes which split open immediately.
SAND LIZARD (Lacerta agilis)
The sand lizard’s back and sides are a grey-brown or brownish and the flanks sometimes feature dark patches with light centres. Individuals may show various patterns of broken stripes and spots along the body and males show a vivid grass green colouration during the breeding season. The sand lizard is similar in appearance to the common lizard but adult sand lizards are often quite bigger. They also appear more stocky and have proportionally larger heads. If you see a lizard in the wild that has vivid green colouration it is unmistakably a male sand lizard in its early season mating condition. They grow up to 20cm in length. Sand lizards are a very rare and a protected species in the UK. They are found only in a few areas of southern heathland, such as the New Forest, and the sand dunes of the the north west. They hibernate in burrows during October before re-emerging in milder weather, usually between March and May. They can live for up to around 12 years, though many will die at the early stages of life, perhaps taken by predatory birds or dying during their winter hibernation.
The Sand lizard diet comprises almost entirely of invertebrates which includes spiders, grasshoppers and crickets. Male Sand lizards have been known to eat their own young, and the young of common lizards. This is due an instinctive reaction to fast-moving prey items of an appropriate size. Whilst they eat daily when food is available, as with all reptiles, they can last for considerable periods without eating. Their main natural predators are birds of prey and the rare Smooth snake. The main threat from mammals comes from Foxes, Badgers and Weasels plus domestic cats. It is ironic that Britain’s rarest reptile, the Smooth snake, predates Britain’s second rarest reptile, the Sand lizard!
The sand lizard is the UK’s only egg laying lizard. They emerge from hibernation from late March to April and lay eggs in late May or early June. The eggs are left buried in sand exposed to the sun which helps to keep them warm. Eggs hatch between late August and September. The sand lizard is dependent on well managed heathland or sand dune habitats, where it occupies mature vegetation that provides good cover. As in the case of the Smooth snake, it has been subject to habitat loss over several decades with many of the areas in which they were found taken over by housing development.
Thanks to a captive breeding and reintroduction programme operated by Amphibian and Reptile Conservation, sand lizards have been returned to suitable areas of the UK in order to colonise. By 2010, the whole project had released 9455 lizards and the success rate continues to be high The programme has concentrated on establishing new colonies on habitats where the species was absent. The New Forest Reptile Centre which is managed by the Forestry Commission is part of this project.