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Reptiles

Background

There are six British reptile species that can be encountered in the UK of which four are widespread and relatively common.  These are: common lizard Zootoca vivipara; slow-worm Anguis fragilis; grass snake Natrix natrix; and adderVipera berus. The remaining two species, smooth snake Coronella austriaca and sand lizard Lacerta agilis, are very rare and have restricted distributions and specialist habitat requirements.

Common Lizard

The common lizard is the UK’s most widespread reptile species, inhabiting a wide variety of habitat types including heathland, woodland, abandoned and derelict land, larger gardens and downland. Some south facing slopes of railway embankments and similar man-made slopes and berms can also be important habitat. They prefer a mosaic of different levels of undergrowth with a variety of basking sites to allow body temperature control by moving in an out of sunnier or shadier spots.  They emerge from hibernation in March or April, and mate a few weeks later.  At night they hide in burrows or crevices.  The young are born in August or September in thin transparent membranes which split open immediately.  Litter size ranges between 3 and 12.  Males become sexually mature at around two years of age, females at around three years. Preferred prey items include earthworms, snails, various insects and spiders.

Common lizard (Zootoca vivipara) - Rare plain morph

Common lizard (Zootoca vivipara) - Rare plain morph

Slow-worm

Slow-worms can be found in a diverse range of humid habitats across the whole of Britain, but their populations are highest in the southern counties.  Slow-worms inhabit open countryside and urban habitats and can be found in woodland, grassland, heathland, gardens, allotments, and abandoned / derelict land. They spend much of their time in deep cover beneath logs and rocks or below ground in holes, tunnels, crevices or in soil surface layers.  Despite its snake-like appearance the slow-worm is a lizard (but with no visible legs). Slow-worms mate in April-May, and live young are born in late summer. An average of 6-12 young (although as many as 26 have been recorded) are born after a gestation period of 3-5 months. Slow-worms hunt after dusk or following rainfall and they concentrate on slow-moving prey invertebrate prey such as slugs. Slow-worms hibernate throughout the winter months, sometimes sharing hibernacula with other reptile species.

Slow-worms (Anguis fragilis)

Grass snake

The grass snake is the UK’s only egg-laying snake and the largest land reptile found in Britain at over one metre long when fully grown.  It is typically closely associated with water, with marsh and wetland being favoured habitats, but will also frequent woodland edge, ancient hedgerow, parks and gardens.  Adults eat mainly frogs and toads with some fish, but will occasionally eat nestling birds and small mammals.  Mating takes place in April-May and a clutch of soft shelled eggs (8-40, depending upon the size of the female) is laid in June or July. While compost and manure heaps are favoured nest sites, as they provide suitable egg incubation temperatures, grass snakes will make use of other man-made features for egg-laying, such as the underside of patio areas that are heated by the sun and retain heat. A communal nest site may contain over a thousand eggs, and the young hatch in August or September after an incubation of about 10 weeks. Males become mature at three years of age, but females do not begin to breed until they reach their fourth or fifth year. After reaching maturity, males shed their skin twice a year, whereas females slough their skin once a year just before egg-laying. They hibernate from October to March, often communally, under tree roots, in old rabbit burrows, or in piles of manure. Grass snakes can live for up to 15 years.

Grass snake (Natrix natrix)

Adder

Adders are able to utilise a diverse range of habitats including lowland meadow, hillside, moorland, marshland, woodland, scrub and heath. They show a marked preference for sites with a southerly aspect. Adders hibernate through the winter and emerge in late winter / early spring, when they can frequently be seen basking near the hibernacula. Prior to mating the males wrestle for dominance, often referred to as a “combat dance”. After mating adders disperse to their summer feeding areas that can be as far as 1km away from the hibernacula. The young are born in late summer in egg membranes which break open immediately.  Typically there might be as many as ten young in a clutch, but female adders in Britain normally only give birth every other year.  The young feed on small lizards and mice, adults feed mostly on fully grown rodents.  Adders are venomous.  They strike their prey then follow it by scent and swallow it once the venom has immobilised it.

Adder (Vipera berus)

 

Conservation status

Many species of reptiles are in decline and, according to recent studies by the IUCN, two-fifths of all reptile species are affected in this way.

All six UK reptile species have undergone local, regional and national declines over the course of the last century due to urbanisation, agricultural intensification, fragmentation and poor management, alongside other reasons.

The rarer species – sand lizard and smooth snake – have very restricted distributions as a result of their reliance on specialist heathland and dune habitat.  Conservation efforts including reintroductions, habitat creation and restoration have reversed this trend to some extent, but the patchy and localised distribution of both species leaves them vulnerable.

Legislation

All UK native reptile species are protected by law.  The Wildlife & Countryside Act 1981 (and later amendments) provides the legal framework for this protection.  Sand lizard and smooth snake and their places of shelter have the greatest level of legal protection under Schedule 2 of the Conservation of Habitats and Species Regulations.

Smooth snake (Coronella austriaca)

 

The more widespread and common reptile species, namely common lizard, slow-worm, grass snake, and adder are protected against deliberate or reckless killing and injury.  Reptiles are likely to be threatened and the law breached by activities such as the following:

  • Archaeological and geotechnical investigations
  • Clearing land, installing site offices or digging foundations
  • Cutting vegetation to a low height
  • Laying pipelines or installing other services
  • Driving machinery over sensitive areas
  • Removing rubble, wood piles and other debris.

All species of reptile are priority species in the UK BAP and have been adopted as Species of Principal Importance under Section 41 of the NERC Act (2006) in England  under Section 42 of the same Act in Wales.

Licensing

A survey licence is required to survey sand lizard and smooth snake – Applied Ecology Ltd ecologists hold survey licences for both species.

A survey licence is not required to survey for common lizard, slow-worm, grass snake and adder in England, Scotland and Wales, or to survey for sand lizard or smooth snake using methods that do not result in offences (e.g. assessing habitat quality).  Survey licences are issued by Natural England, the Countryside Council for Wales, Scottish Natural Heritage, the Northern Ireland Environment Agency or the National Parks and Wildlife Service (Republic of Ireland), depending on site location.

In Northern Ireland and the Republic of Ireland, a licence is required to survey for common lizard.

Survey

A number of methods can be employed to survey a site for reptiles during the reptile active season:

  1. A visual search for reptiles basking out in the open
  2. Looking for reptiles beneath existing sheltering/basking locations present within a site
  3. Systematic checking of artificial refugia laid down across the site, specifically to attract reptiles

Reptile survey using artificial refugia is the most frequently used and reliable method for assessing reptile presence or absence on a site. Refugia typically consist of metal sheets (corrugated tin or similar), or bitumastic roofing felt cut to approximately 0.5 metre square (for ease of transportation).  They are laid out in habitats considered suitable for reptiles and, after a period of about two weeks, are checked for the presence of reptiles on or under them.  Reptiles are ectothermic and require solar radiation to reach their optimum body temperature.  The refugia heat up and provide reptiles with a warm surface on which to bask or shelter under.  At times of the year when day time temperatures are relatively low such as in the spring and autumn, reptiles will use the refugia more frequently compared to the warmer summer months when air temperatres are higher.  In light of this, reptile surveys completed in the spring and autumn tend to be more reliable than those completed in the summer, and arguably require fewer repeat visits to sufficiently demonstrate reptile absence.  Typically seven separate visits in suitable weather during a spring or autumn survey would be sufficient to prove reptile presence or absence from a site where refugia have been set out at appropriate densities in all potentially suitable habitat areas.

Mitigation

The presence of any reptile species on a site is a material planning concern, and mitigation measures should be agreed to minimise the risk of the development resulting in the killing or injury of reptiles as part of the planning application process. Where possible reptile friendly habitats should be preserved on site and reptiles populations conserved in situ.  Where this is not practicable, reptiles may need to be re-located to suitable alternative habitats close by.   Reptile mitigation strategies can be time consuming and costly to plan and implement -particularly if they need to be based on habitat creation and managment of off site land that is not in the ownership of the developer. Typically land areas supporting reptiles that need to relocated in advance of construction would be enclosed with reptile proof fencing, and artificial refugia used to help capture reptiles during the reptile active season.  The amount of capture effort required to clear a site of reptiles will be dependent upon the size of the reptile population, the time of year and prevailing weather conditions.

Applied Ecology Ltd has extensive experience in planning and implementing reptile mitigation schemes to enable development, and owns, manages and monitors a large reptile receptor site in Sussex that has been used to re-home reptiles.

Click HERE to read about a reptile translocation project carried out by AEL.

See Survey Calendar for survey timings.

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