Zootoca vivipara

Appearance

The length of the body is less than 12 cm . The tail is up to two times longer than the body, although it is often partially or wholly lost. The limbs are short, and the head is rather round. Males have more slender bodies than females. The neck and the tail are thick. The collar and other scales seem jagged.

The colour and patterning of this species is remarkably variable. The main colour is typically medium brown, but it can be also grey, olive brown or black. Females may have dark stripes on their flanks and down the middle of their backs. Sometimes females also have light-coloured stripes, or dark and light spots along the sides of their backs. Most males and some females have dark spots in their undersides. Males have brightly coloured undersides – typically yellow or orange, but more rarely red. Females have paler, whitish underparts. The throat is white, sometimes blue.

Behavior

The viviparous lizard feeds on invertebrates, mostly small insects. It shakes larger prey in its jaws before chewing it and swallowing it whole. In early spring, late autumn, and cool summer days, it basks in the sun to reach its optimum body temperature, which is about 30°C .

These lizards mate in April or May. Males take females in their jaws before mating – if the female is not interested, she will bite the male fiercely. The offspring develop for about three months inside the female.

The name of the species is derived from its ability to give birth to live young, an adaptation to a cool climate, but some southern populations are oviparous . The three to 10 young are usually produced in July. The blackish young measure about 3 cm , and when first born are surrounded by egg membrane, from which they break free after about a day. Males reach sexual maturity at two years old, females at three years old. Individuals from viviparous and oviparous populations may be hybridised, but with significant embryonic malformation. Viviparous ''Z. vivipara'' do develope placentae to facilitate pregnancy but there is no substantial transport of nutrients as seen in some other species of viviparous reptiles .

In northern regions, viviparous lizards begin hibernation in September or October, underground or in log piles. Hibernation ends about mid-February. Further south, the species is active throughout the year.