Species of the day: Common Lizard

By James Duncan

Learning and Engagement Officer

The Common or Viviparous Lizard (Zootoca vivipara) is one of just three native Lizard species. Along with the leg-less Slow-Worm it's the other you're most likely to see. The naming of this species relates to its unusual habit (amongst lizards) of incubating eggs inside the body and giving birth to live young - they are born within a transparent membrane, though the young will struggle through this within a day or so and become fully independent. Of course nature rarely sticks to our arbitrary rules of naming and the Viviparous Lizard tends to be oviparous (egg-laying) in southern parts of its range, particularly at altitude in the Pyrenees. Remarkably, this species has perhaps one of the widest distributions of any known vertebrate on the planet. Their range extends not just through mainland Europe, but into the Arctic Circle, through Asia to the Pacific coast of Russia and even as far afield as Japan. Living further north than any other non-marine reptile, it truly is a species of the temperate zone. In contrast, its 'common' moniker somewhat belies its UK status, which would be more accurately determined as 'local.' In essence their distribution here is patchy and they're in decline owing to loss of habitat. 

It's certainly possible that the Viviparous Lizard may be seen in larger gardens. Truthfully it's not their favoured habitat as they're largely a creature of undisturbed land such as heath and upland moor, though roadside verges, forest rides, wood-piles, artificial embankments, river edges and railway cuttings may also fit the bill nicely. The majority of our most familiar landscapes, such as farmland, grazed pastures and dense woodland are entirely unsuitable for them. Now's the perfect time to keep a look out as they typically emerge from hibernation prior to the start of spring, with courtship and mating peaking in April - May. Courtship's a complex affair as they're polygynandrous, whereby both sexes will have multiple partners during the breeding season. Look out for them as they 'bask' in full sunshine, anywhere within easy reach of cover. As with all 'cold-blooded' reptiles, Viviparous Lizards are wholly reliant on thermoregulation. They need the heat to warm their blood, missing an ability to regulate their own body temperature in the same way that mammals do. Being a diurnal (daytime) hunter they'll typically emerge from overnight refuge with a body temperature of around 15°c. When basking achieves an optimum 30°c, they're ready to move off in search of invertebrate prey. They're an agile, hyper-alert species and it's typically sound, rather than sight, that alerts humans to their presence. Always on the lookout for danger, their explosive movements often promote a rapid rustle of leaves as they disappear from view.    

Surprisingly, Viviparous Lizards also appear to be fairly adept swimmers, occasionally catching insect prey from the water surface. This may even be used as a tactic for escaping predators, of which they have many. Their agility aside, they frequently fall prey to birds such as Kestrel and Buzzard, mammals such as Weasel and Hedgehog and other reptiles such as Adder and Smooth Snake. Their susceptibility to both domestic cats and even garden Blackbirds likely limits their urban distribution. They do have a strategy to escape, a special trick using autotomy. This is of course, self-amputation, shedding of the tail. Contractions in the muscles of the tail continue after detachment, the tail wiggling to attract the predator's attention away from the escaping lizard. This has particular benefit towards venomous snakes, whereby even a small strike will quickly inject enough venom to kill. Should the Viviparous Lizard be struck in the tail, it can be shed rapidly before the venom spreads. They can re-grow the tail, though not to the full extent of the original.

Common Lizard © Sean Stones