Reptiles
Sand Lizard
Lacerta agilis · also called agile lizard
For most of the year the sand lizard is an easily missed brown reptile of dry, sandy ground. Then spring comes, and the males light up — their flanks turning a brilliant grass green as they display and fight for territory on the open heath. In Britain it is the rarest lizard, clinging on at a handful of sites and only there because people breed and release it.
Overview
Lacerta agilis is a stocky, blunt-headed lizard, up to about 20 cm long, brown or grey with a bold row of dark, pale-centred blotches down the back and flanks. Breeding males turn vivid green on the sides and belly. It lives across a wide band of Europe and central Asia on sandy heaths, dunes, dry grassland, and steppe, and it hunts insects and spiders by sight.
Eggs in the sun
Unlike the live-bearing common lizard it often shares ground with, the sand lizard buries its eggs in warm, bare, south-facing sand and lets the sun incubate them. That ties it completely to habitats that stay open and sunny, and it vanishes where heath and dune scrub over, are disturbed, or burn.
Britain’s rarest lizard
Britain has only three native lizards, and the sand lizard is much the scarcest, surviving naturally on lowland heaths in southern England and dunes on the north-west coast. A long captive-breeding and reintroduction programme has restored it to Wales, Cornwall, Devon, and Kent.
Status
The sand lizard is Least Concern across its huge Eurasian range but declining in the north-west. In Britain it is rare, fully protected, and dependent on ongoing heath and dune management and restocking.
Sand Lizard: common questions
Why do male sand lizards turn green?
The green is a breeding signal, produced and maintained by hormones from spring onward and reaching its most intense at the height of the mating season in April and May. A bright, extensive green flank advertises a male's condition and fighting ability to rival males, and males with more vivid green tend to win contests and hold better territory. It may also matter to females choosing a mate. Green skin also reflects ultraviolet light, which lizards can see, so part of the signal is invisible to us. After breeding the colour fades back toward the normal brown, and females and young are brown year-round, though older females can show a little green.
How is a sand lizard different from a common lizard?
The sand lizard is bulkier and more heavily built, with a noticeably blunt, deep head and short legs, and it grows a little larger, to around 20 cm. Its pattern is bolder, a series of dark blotches with distinct pale or white centres, called ocelli, running along the back and sides, and breeding males are green on the flanks. The common, or viviparous, lizard is slimmer and more uniformly brown with finer markings, and males have an orange spotted belly rather than green flanks. The two also breed differently, the sand lizard laying eggs in sand and the common lizard usually giving birth to live young.
Where can you see sand lizards in Britain?
Naturally they survive on a scatter of lowland heaths in Dorset, Hampshire, Surrey, and West Sussex, and on sand dunes along the coast of Merseyside and Lancashire, particularly around the Sefton coast. Reintroduction has added sites in Wales, Cornwall, Devon, Kent, and elsewhere. The best chance of a sighting is on a warm, still, sunny morning in April to June, when males are green and active, at a well-managed heath or dune with plenty of bare sand and low heather, where the lizards bask on south-facing banks and sandy patches close to cover. All British sand lizard sites and the lizards themselves are legally protected, so watching should be done from paths without disturbance.
Why did the sand lizard decline in Britain?
Its problem is habitat. Lowland heath and coastal dune, the only places it can breed in Britain, have been lost on a huge scale to housing, farming, forestry, mineral working, and golf courses, and much of what remains has become overgrown as traditional grazing and cutting stopped, shading out the bare sunny sand the lizard needs for its eggs. Fragmentation left small populations isolated and unable to recolonise. Wildfire on dry heath, disturbance, and predation by domestic cats and introduced predators add further pressure. Recovery has depended on restoring and re-linking open heath and dune, and on breeding lizards in captivity to restock cleared sites.