Viviparous lizard, Zootoca vivipara
(Jacquin, 1787)

History and origin
The Viviparous lizard was first described by Jacquin in 1787, the scientific name of this species is Zootoca vivipara, formally Lacerta vivipara. Zootoca from Greek meaning 'to give birth'. vivipara from Latin meaning 'viviparous'.

Viviparous lizard - © Jean-Pierre Vacher
Viviparous lizard, Zootoca vivipara - © Jean-Pierre Vacher

Viviparous lizard - © Dan Kane
Viviparous lizard, Zootoca vivipara - © Dan Kane

Viviparous lizard - © Konrad Mebert
Viviparous lizard, Zootoca vivipara - © Konrad Mebert

Viviparous lizard - © Daniel PhillipsJuvenile Viviparous lizard, Zootoca vivipara - © Daniel Phillips

Characteristics
This lizard is oviviparous, sometimes laying eggs (usually in the south, otherwise giving birth to young (generally in cooler parts of their range). This species may lay it's eggs or give birth according to weather conditions (heat, humidity...). They occur north of the planet then any other reptile (350 km into the Arctic circle).

Description
=Size=
In the case of egg laying (occurring in the south) they measure 10 x 8 by 12 x 10 mm. The young measure 15 to 25 mm long when they hatch. They can grow up to around 65 mm long, their tail being the same size to 1.5 the length of the body making an adult size of between 100 mm to 130 mm long.
=Morphology=
They are a stocky, robust, short limed lizard. They have a very chunky relatively short tail (in comparison with other lizards in the region), they have a small yet robust head that appears blunt and rounded.
=Patterns & colours=
The newly hatched are uniform dark. They are usually olive-brown or dark brown. Males have darker sides then females, sometimes with a light line running along the top of the flank, they also have numerous light markings on the back bordered by a dark colour. Females are usually more uniform and also have dark sides, they however lack the white patterns on the back but they have at the place of a light line on the top of the flanks, they have a dark one.

Geographical range
They are found all over Europe except for the Mediterranean islands, most of the Iberian peninsula (except the Pyrenees and the northern coast of Spain). Also absent from most of Italy (except for the Alps). Also not present in Greece, Albania and extreme eastern Europe (southern Ukraine, east Romania, east Bulgaria... This species is found up within 350 km of the Arctic circle.

Subspecies
- carniolica - Found in Slovenia and north eastern Italy.
- pannonica - Found in south eastern Europe.
- vivipara - Found over most of the range.

Sexual differences
Males general pattern is more constant and vivid, they seem to have dark flanks and a lighter back which also has numerous light spots.

Seasonal variations
Females are larger in spring due to their eggs.

Diet
They feed on insects.

Defensive habits
They flee into dense vegetation. They can swim well and sometimes use this as an escape method when disturbed when they're close to water.

Reproduction
Although normally quite docile within a social group, the males may become very aggressive during the breeding season. During this period a male may guard a certain zone containing several females. Despite this, the female usually mates with more then one male. Breeding occurs when they wake up from hibernation in spring. They usually give birth to 11 young, however, in Spain and the Pyrenees and other southern parts of its range, they have been known to lay eggs. In the case of egg laying, the eggs develop for around only 4 to 5 weeks. The eggs can sometimes be laid with other eggs of the same species. In the case of birth giving, they usually give birth to fully formed dark specimens, they are usually encased in a transparent membrane from which they quickly escape, this happens in July.

Sexual maturity, life span
The average life span for Zootoca vivipara is around 12 years, many specimens die after their first mating season. They reach their sexual maturity in their second year.

Habits
They are active by day. They are a ground dwelling lizard, they rarely climb, but when they do, they only climb in dense bushes where they will only go around 30 to 50 cm off the ground. They are good swimmers. They can be found in large populations, sometimes up to 1000 per hectare.

Habitat
They are found under 1000 meters in altitude, although in the south they have been found in altitudes exceeding 1900 meters. They inhabit humid habitats, like grassland near marshes, dense green vegetation, wet ditches, moist woods with lots of dead leaves and humid ground, in fields...

Predators
They are the prey for snakes, birds.