Sand lizard (Lacerta agilis)
|French:||Lezard des Souches|
|Size||Adult body and tail length: 18 - 20 cm|
Adult weight: 12 g
The sand lizard is classified as Least Concern (LC) on the IUCN Red List (1). Listed under Annex IV of the Habitats Directive and Annex II (and Recommendation 26) of the Bern Convention. It is protected in the UK under Schedule 2 of the Conservation (Natural Habitats, etc.) Regulations (1994), and Schedule 5 of the Wildlife and Countryside Act, 1981.
The sand lizard (Lacerta agilis) is larger than the common lizard, and somewhat stockier. Sand lizards have an attractive pattern of dark spots with light centres (ocelli), over a background of brown or grey. Males develop vivid green flanks in the breeding season (April to May). Juveniles are a more uniform brown, with distinct ocelli. There is some regional variation in appearance between animals from the north of England and those in the south, which are darker overall.
The sand lizard ranges from France, east across Europe into Mongolia, southern Russia and Northern China, and as far south as northern Turkey. Britain marks the northwestern-most limit of its range, where it is now found naturally only on scattered sites in Dorset, Surrey, Hampshire and Merseyside. It has been introduced to Berkshire, West Sussex, Cornwall, Devon and North Wales, in recognition of the fact that it used to have a wider range encompassing parts of south-east England, parts of the southwest, and North Wales/northwest England.
Typical habitats for the sand lizard are lowland dry heathland and coastal sand dunes, though they do occur at low densities in some other habitats. Sand lizards need a variety of structural and temperature conditions to allow them to regulate their body temperature and seek cover from predators. Dense heather and marram grass help to provide this in their typical habitats. A key requirement is for unshaded sand patches, in which to dig burrows for egg-laying and for shelter.
The sand lizard is Britain's only egg-laying lizard. The eggs, laid in late-May to June in burrows dug into the sand, are incubated by the heat of the sun. The clutch often numbers from 4 to 14 and the young hatch in late summer. At hatching, the lizards are about six centimetres in length. At this time of year invertebrate prey is abundant and the hatchlings grow a few more centimetres before hibernation.
Sand lizards are 'ectothermic', which means they are unable to generate their own body heat and need to bask in the sun, or be in contact with warm surfaces, to raise body temperatures. It is often said that lizards are 'cold-blooded' but in fact this is not true: their blood temperature varies with the environmental conditions, and therefore in high summer sand lizards actually have warm blood. They are active in warm temperatures, and the lizards pursue activities such as mating or foraging. Sand lizards retreat to a burrow or other refuges by the time the sunlight fades, and remain inactive during the night. In some conditions they may also remain inactive in burrows during the day, for instance in very hot weather.
During the winter months they hibernate in burrows, remaining in a torpid state before re-emerging in milder weather, usually between March and May. Sand lizard populations are often centred on topographical features such as a bank or mound, and do not disperse over long distances. 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 hibernation.
The principal reason for the decline of the sand lizard is the massive loss of its habitat. During the 20th century, in north-western Europe and in the UK, large areas of heath disappeared for development or agriculture. Native sand lizards have been lost from Kent, Sussex, Hampshire, Wiltshire, Berkshire, Cheshire and Wales. The surviving populations are often fragmented, surrounded by conifer plantations and built land. Heathlands are also highly susceptible to fire and damage through recreational use.
Due to the drastic reduction in numbers, the sand lizard is protected by the Wildlife and Countryside Act 1981 and under the Conservation (Natural Habitats etc) Regulations 1994 (both of which implement European legislation). It is also included in English Nature's Species Recovery Programme. Efforts to increase the populations of this attractive reptile include the protection of existing sites, management and re-creation of heathland and dunes suitable for the lizards, and reintroduction of animals to specially prepared sites within their known or presumed former range. This is achieved through a number of initiatives, including specific sand lizard conservation work led by The Herpetological Conservation Trust, along with more general heathland work by conservation organisations including English Nature, RSPB, The Wildlife Trusts, MoD and the National Trust. In the last few years, sand lizards have been re-introduced to sites in Dorset, Hampshire, Surrey, Devon, Cornwall, Hampshire, West Sussex, Berkshire and North Wales.
Find out more about reptile conservation:
Amphibian and Reptile Conservation:
Information supplied by English Nature.
- Hibernate: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Incubate: to keep eggs warm so that development is possible.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
- Torpid: sluggish and inactive.
IUCN Red List (April, 2011)