Captive breeding sand lizards

SAVING SPECIES

Sand Lizard Captive Breeding and Release Programme

Why captive breed sand lizards?

The sand lizard provides a good example of the advantages of captive breeding. In the wild, the eggs are laid in shallow sand in dunes or on heathland and they're exposed to many dangers - unseasonable weather changes can dry them out or cause them to hatch too late in the year for the young to survive, or to not hatch out at all; just one mountain biker or horse rider travelling along a sandy track can destroy several clutches of eggs. Even before they are laid the eggs may not be viable - many populations are small and isolated which can result in inbreeding. Once these other factors are taken into account, as few as half the eggs laid might hatch out, and that's in a good year.

When the young do hatch out they are small and extremely vulnerable, especially to predation, and are faced with the task of finding as much food as possible in the few short weeks before hibernation. As a consequence of these and other pressures, only around 5% of these youngsters survive to maturity.

We know that, with amphibians, a large number of young are produced because so few are expected to survive, and to some extent this is true with reptiles. However, when there are only a handful of isolated populations left, this low survival rate could spell disaster for the whole species.

With captive breeding survival rates are much, much higher. Hatch rates are improved by incubating the eggs in controlled 'vivaria', and the young hatch earlier and are well fed before release. Once in their new habitat they still have time to establish themselves and feed up before winter. For these individuals maturity is often reached a full season earlier.