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Reptile Surveys

Reptiles are protected from killing and injury

Why might I need a reptile survey?

All native reptiles in the UK have some degree of protection, with our rarer species given full protection. In order to avoid potential prosecution, it is therefore necessary to assess the status of reptiles on any development site. This can be done during initial surveys where the surveying ecologist will assess the likelihood of reptiles being present given the habitats that are on site. If it is decided that there is the possibility of reptiles being present and that they may come to harm by the development, then a reptile survey may be required.

Introduction to the UK’s reptiles

Here in the UK, we only have six species of native reptile; three lizards and three snakes. Four of these, the slow worm Anguis fragilis, the common (or viviparous) lizard Zootoca vivipara, the barred grass snake Natrix helvetica, and adder Vipera berus are fairly widespread across the UK.

However, Northern Ireland (and the island of Ireland as a whole) has only one species of native reptile, the common lizard (contrary to popular belief, this is not due to the antics of Saint Patrick, but simply due to the fact that Ireland became separated from Great Britain before other reptile species had reached it following the last Ice Age).

There are two other native species which are much more restricted in their range; the sand lizard Lacerta agilis and the smooth snake Coronella austriaca, both of which are mainly restricted to southern heathland and dune sites in England, although there are populations of sand lizard in north Wales & the north-east of England, some of which have been re-introduced.

Interestingly, only two of our six reptile species lay eggs (the barred grass snake and the sand lizard), with the rest giving birth to live young.

slow worm

Slow worm

  • The most likely reptile to be encountered and are widespread throughout Britain.

  • Not a worm (or slow), but a legless lizard that spends much of its time underground.
  • Can grow to around 50cm in length, but usually significantly smaller than this, particularly when they have lost their tail as a result of an encounter with a predator (likely cats or corvids).
  • One male in captivity lived to be 54 years old!

Common Lizard

  • Widespread across Britain and in Ireland but they are difficult to find as they tend to quickly run for shelter if disturbed. Can be found across a variety of habitats and can commonly be spotted basking in the sun on warm days.

  • A small lizard species, with a maximum length of around 15cm (although around 10cm is more common for adults) of varying colouration but typically brown or green often with dark spots or lines giving them a striped appearance
  • Has the ability to re-grow their tail if it is lost, although it will not be as long as the original.
common lizard
Sand lizard

Sand Lizard

  • Very rare and only found in few locations in England but reintroductions have been successful in new locations, including Wales.

  • Larger and stockier than the common lizard, reaching around 20cm in length, but looks similar except for rows of spots along their backs. 
  • Two distinct races, the ‘dune race’ which is much brighter in colour, and the ‘heathland race’ which is darker in colour and more mottled. Both races are sexually dimorphic, with the males displaying much more green than the females, particularly during the breeding season.
  • A European Protected Species, meaning that a license is required to survey for them.


  • Widespread throughout Britain but very localised due to their habitat requirements. Can be found basking on heathlands, woodland rides, dunes, and other scrubby habitat.

  • The UK’s only venomous snake, but a shy species that does not seek conflict.
  • Quite a stocky but short snake, with adults between 60-80cm. They can be strongly sexually dimorphic, with the larger females usually being brown with a darker brown stripe, and the males grey or brown with a black stripe, although this can be less obvious just before sloughing, where the males can appear quite dull in colour.
Grass snake

Grass snake

  • Widespread in England and Wales but absent from Scotland.
  • The UK’s largest snake species, can reach lengths of up to 150cm. Variable in colour but typically green, brown or grey and have a very distinctive yellow collar around the neck. Has a distinctive yellow collar around the neck (but very old females can lose this with age).
  • A skittish species, can be difficult to see basking out in the open.
  • Non-venomous, relying on chemical deterrents to put off some would-be predators.

Smooth Snake

  • The UK’s rarest reptile, confined to sandy heaths in the south of England.
  • A similar length to the adder (around 50-70cm), pale olive and brown in colour, looking like a smaller grass snake but without the yellow collar and much more slender in build.
  • Specialises in preying on reptiles, including sand lizards with whom they share  a habitat.
  • Non-venomous, but they will bite as a deterrent.
  • A European Protected Species, meaning that a license is required in order to survey for them.
smooth snake

Reptiles and the Law

All six of the UK’s native reptiles are protected under the Wildlife and Countryside Act 1981 (as amended), which means that it is an offence to intentionally kill or injure a reptile. In Scottish law, the word ‘recklessly’ is also included – anyone breaking this law could be subject to a £5000 fine for each offence, and/or a prison sentence.

Two species, the sand lizard and the smooth snake, are designated as ‘European Protected Species’ under the EU Habitats Directive, which provides additional protection. This additional designation means that for these two reptile species, it would also be an offence to deliberately or recklessly:

  • Capture, injure or kill animals of such species
  • Disturb animals of such species
  • Take or destroy the eggs of such an animal
  • Damage or destroy a breeding site or resting place of such an animal

Although it is highly unlikely (unless you are in a particular geographical area) that you will encounter one of the two European Protected Species of reptile in the UK, all our reptiles are protected from killing or injury. As some species can be found over a large range of habitats, it is important to determine whether reptiles are present on a site before any groundwork begins, both to protect any reptiles present, and ensure compliance with the law.

Reptile Surveys

An initial assessment will be made of a site during a Preliminary Ecological Appraisal, including determining whether the habitat looks suitable for supporting reptiles. Reptile surveys are usually conducted through a combination of walking transects and placing a series of artificial cover objects (ACOs) that warm up in the sun to which reptiles are attracted. They are then checked, usually after they have been left for a two-week period.

These surveys are usually conducted over a number of visits,  and will enable the ecologist to determine which reptile species are present, and give an idea of the population size(s). It can then be determined how best to avoid, mitigate, and/or compensate for detrimental impacts to the reptiles on-site.

As all reptile species greatly reduce their activity during the winter, these surveys are recommended to be undertaken between April and September.

Reptile survey

Frequently Asked Questions

Download our free survey calendar to ensure that surveys are scheduled to form part of your timescale.