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BiologyDuring early spring and late autumn (either side of hibernation), the viviparous lizard invests much of its time in basking in the sun. Basking also occurs throughout the summer, when the lizard needs to warm itself up sufficiently in order to hunt, particularly on overcast or cool summer days. When they first emerge in the morning, the body temperature of these cold-blooded (poikilothermic) animals is typically around 15°C; their optimum temperature is 30°C, which is attained through basking. This lizard is extremely agile and alert, rapidly dashing for cover if disturbed. They hunt in vegetation for invertebrates, which are shaken in the jaws before being chewed and swallowed whole (2). In England, breeding tends to occur in April and May. Males are at their most vibrant at this time, as they shed their old skin prior to the breeding season. Some fighting occurs between males over females, but this is generally less intense than in the sand lizard. Males take females in their jaws prior to mating; if a female is not receptive, she will bite the male fiercely (2). The eggs take around three months to develop inside the female. As the common name 'viviparous lizard' implies, the female gives birth to live young. Between 7 and 8 young are typically produced; they are black in colour and surrounded by an egg membrane, from which they will free themselves after around one day. Sexual maturity is reached at two years of age in males, and three years in females (2). Adults begin to hibernate in October; it is not yet clear where hibernation takes place, but underground refugia or log piles seem likely candidates. In southern England and Wales, male viviparous lizards can emerge from hibernation as early as February (2).