Reptile fact file

Reptiles took the evolutionary advances of amphibians a step further by developing a dry, scaly, waterproof skin - which allowed them to move into drier areas - and the ability to breed on land.

Some reptiles - including crocodiles and turtles - have returned to water, and a complete account of Cornwall's reptiles should include the various turtles which range into our seas. Most notable is the leathery turtle, which can grow to over eight feet in length.

Cornwall's land-living reptiles must bask to absorb warmth, and this gives clues as to where and when to find them. Outside their winter hibernation, they can often be found basking in the early morning sun - for especially long periods on cool spring days.

Heaths, dune systems, hedges and verges with south-facing slopes, offering open sun-traps next to thick groundlevel vegetation into which they can escape when danger threatens, are among the favoured reptile habitats.

Reptiles have been getting a bad press ever since the days of Adam and Eve. They continue to suffer persecution today, even though it is illegal to harm them, but loss of habitat diversity in the countryside is mainly to blame for their decline.

Adder

With its striking zig-zag markings and fearsome - although undeserved - reputation, the adder is one of our most exciting wild animals. In truth, this small snake's bite is very unpleasant (and merits urgent medical help) but is extremely unlikely to kill you - you have much more chance of dying from an insect sting.

The adder has much more to fear from humans, and makes every effort to avoid us. If you must stray off the paths and into its habitat, do it heavily and noisily to give warning of your approach. Cornwall is luckier than most areas in having so many adders, which help to control our populations of small mammals.

Grass snake

Our largest reptile, growing to over five feet in length, is marked by a distinctive yellow collar. It seems to be more demanding in its habitat requirements than the other "common" species, which helps to explain the grass snakes alarming decline. Wet areas for hunting prey such as frogs, drier areas for basking and sheltering, and rotting vegetation for egg laying must all be provided.

Only this species and the sand lizard lay shelled eggs instead of giving birth to live young. You can help grass snakes by building a special compost heap to keep their eggs warm - the Trust will tell you how.

Common lizard

This agile and alert creature is present in many a Cornish hedge or verge, but seldom noticed. Its colours are often confusingly similar to those of the rare sand lizard recently reintroduced to Cornwall, but that species' much stockier build is the key difference.

All of our reptiles mate in spring, producing perfect miniatures of their adult form by late summer, but the young of this species appear from as early as June. Insects and spiders are its main prey, and in common with the other lizards its predators include fellow reptiles as well as a host of birds and mammals.

Common lizard
Photograph by David Chapman

Slow-worm

To tell a legless lizard from a snake, look it in the eye - if it winks at you it's a lizard, as snakes have no eyelids. Another friend of the gardener, this lizard favours damp corners where slugs and other "squashy" prey might be found, and is often revealed by turning rocks, wood, metal sheets or leaves.

Lizard tails can be shed to escape predators, and slow-worms in urban areas rarely have theirs intact - cats are normally to blame. All reptiles shed their old skin at least once a year - look out for fragments of sloughed lizard skin or complete snake sloughs.

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