Durham Priority Species
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Reptiles Action Plan

Priority Species: Adder, Slow Worm, Common Lizard

1. To maintain and enhance populations of native reptiles in the DBAP area and where possible expand existing populations through conservation management and site protection
2. To safeguard all known or historic reptile sites, and ensure their appropriate management.

Adder Targets
Vision Statement: For adder numbers to remain at least at 1995 levels

Target Type Unit Value
1. To maintain range of adder in Durham BAP area. maintain occupied km squares 30

Slow Worm Targets
Vision Statement: To maintain and then expand the range of slow-worm

Target Type Unit Value
1. To maintain the range of slow worm in the Durham BAP area. maintain occupied km squares 32

Common Lizard Targets
Vision StatementTo maintain and then expand the range of common lizard

Target Type Unit Value
1. To maintain the range of common lizard in the Durham BAP area. maintain occupied km squares 21

All reptiles need external heat sources to raise their body temperature -basking in the sun, or on warm surfaces. This means that most reptiles hibernate between October and March. Even outside this time their behaviour is influenced by weather conditions. They are typically active in warmer weather, but will seek shade on very hot days. Upper temperature thresholds vary for the three species.

Adders (and grass snakes) have fairly large ranges (several kilometres), while the common lizard will stay close to small landscape features such as embankments.

Whilst adders and lizards will bask in the open, slow-worms are generally better hidden in vegetation, or under rocks and other debris.

Adders eat mostly reptiles and small mammals, common lizard feeds on invertebrates such as insects, spiders and woodlice, and slow-worms tend to eat more soft-bodies species such as slugs.

Reptiles require a varied habitat structure that provides a range of shady and sunny spots for body temperature control, as well as frost free areas to spend the winter. They prefer well-drained geology.

Local status

The north-east of England is of high conservation importance for the adder, because of its relative scarcity and its apparent decline elsewhere in the UK. Adders are widely distributed in the west of Durham, particularly in the dales and moors of the North Pennines (favouring rocky tributary valleys over higher moors), but local population trends are unknown.

Slow-worm is probably under-recorded, but is more widely distributed than the adder. Slow-worm is found in the North Pennine valleys, particularly along rocky streamsides, in old quarries and on mining spoil. It is also recorded from the Durham coast, particularly the dene mouths. It may well still occur in other lowland, especially heathland, sites. Some sites are known to have been lost to ‘tidying up’.

Common Lizard is widespread, but uncommon in the Durham area. It favours south facing slopes of the Pennine dales, particularly open heathland and disused quarries and workings. More fragmented populations are found in lowland areas and on the coast.


Habitat loss and modification:

  • Heather moor management involving burning is likely to threaten populations of reptiles.
  • Loss of heathland is a direct habitat loss
  • Overgrazing or regular strimming of vegetation removes resting and feeding areas.
  • Overtidying, such as removal of rubble, earth and debris piles removes basking and overwintering sites
  • Neglect, or afforestation of suitable sites leads to shading and loss of basking areas.
  • Infilling or reworking of disused quarries leads to loss of suitable habitat.


  • Adders and common lizards, which bask in the open, are intolerant of human disturbance, and may suffer from increased public access to sites.

Poor knowledge of distribution:

  • All reptile sites, but slow worm sites in particular, may be destroyed unknowingly if there is insufficient data available to developers and ecologists.