Sand lizard  (Lacerta agilis)

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.