Common lizard
The Viviparous lizardn(Zootoca vivipara) is a Eurasian lizard that lives farther north than any other species of non-marine reptile. It is named for the fact that it is viviparous, meaning it not only lays eggs but also gives birth to live young. Both "Zootoca " and "vivipara " mean "live birth," in Greek and Latin respectively. These lizards are also unique as it is exclusively carnivorous. They live in very cold climates and have the largest range of all terrestrial lizards which even include subarctic regions. It is able to survive these harsh climates as individuals will freeze in especially cold seasons and thaw two months later. They also live closer to geological phenomena that provide a warmer environment for them.
Viviparous lizards do not have a particular colour but can be brown, red, grey, green, or black. The species exhibits some sexual dimorphisms. Females undergo colour polymorphism more commonly than males. A female lizard's display differs in ventral colouration, ranging from pale yellow to bright orange and a mixed colouration. There have been many hypotheses for the genetic cause of this polymorphic colouration. These hypotheses test for colouration due to thermoregulation, predator avoidance, and social cues, specifically sexual reproduction. The underside of the male is typically more colourful and bright, with yellow, orange, green, and blue, and the male typically has spots along its back. On the other hand, females typically have darker stripes down their backs and sides. Additionally, males have been found to have larger heads than their female counterparts, and this trait appears to be sexually selected for. Males with larger heads are more likely to be successful in mating and male-male interactions than smaller-headed individuals. Larger males also have been shown to reproduce more frequently during one mating season compared to smaller males.
Viviparous lizards are widely distributed throughout Europe and Asia. Their range extends to the north of the Arctic Circle. They range from Ireland to Hokkaido (Japan) and Sakhalin (Russia). These lizards are absent from most of the Mediterranean area, although they occur in northern Spain, Northern Italy, Serbia, North Macedonia, and Bulgaria. They are also absent from the area surrounding the Black Sea. In these areas, Viviparous lizards live in damp locations, often near water, including meadows, swamps, rice fields, brooks, and in damp forests. In the northern part of the range, they occur in drier environments, including open woodland, meadows, moorland, heathland, fens, dunes, rocks, roadsides, hedgerows, and gardens.
Viviparous lizards live mainly on the ground, although they may also climb onto rocks, logs, and low-growing vegetation. They are diurnal creatures; in early spring, late autumn, and cool summer days, they are often seen basking in the sun to reach their optimum body temperature. Viviparous lizards are generally solitary, however, some individuals may live in small groups. Due to the cool climate, in northern regions, these lizards begin hibernation in September or October, underground or in log piles. Hibernation ends about mid-February. Further south, however, they stay active throughout the year. Viviparous lizards have a very sharp sense of smell. When they detect odors of predators, they start to flick their tongues rapidly and try to determine the distance to the predator. If the predator is near, the lizard will freeze to seem dead or will blend with the environment.
Viviparous lizards are carnivores (insectivores). They mainly feed on small insects such as flies, cicadas, spiders, and even snails.
Viviparous lizards are polygynandrous (promiscuous) meaning that both males and females have multiple partners. They mate in April or May. The name of these lizards is derived from their ability to give birth to live young, an adaptation to a cool climate; however, some southern populations are oviparous (egg-laying). Females produce 3 to 10 young (or eggs), usually in July. The gestation period lasts about three months. The young are born blackish in color and measure about 3 cm (1.2 in). When first born, baby lizards are surrounded by an egg membrane, from which they break free after about a day. They are completely independent at birth and don't receive parental care. Males reach reproductive maturity at the age of two years, while females become reproductively mature at the age of three years.
The main threat to Viviparous lizards is habitat loss due to urbanization, farming, and tourism development.
The IUCN Red List and other sources don’t provide the number of the Viviparous lizard total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
As predators, these lizards control populations of insects and other arthropods they consume in their diet. In turn as a prey species, they are an important food source for local predators such as dogs, cats, hedgehogs, and snakes.
