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Canadian Herpetological Society





Société d'herpétologie du Canada



Podarcis muralis
Common Wall Lizard / Lézard-des-Murailles


common Wall Lizard

Description
Wall Lizards have long, slightly flattened bodies, and on Vancouver Island, grow to about 18-20 cm total length. They have fairly small slender legs and a distinct neck usually with a smooth-edged collar with slightly keeled scales. Belly scales also are lightly keeled, and Wall Lizards have minute bead-like scales over the entire back and flanks.

Most Wall Lizards are brownish-grey with green highlights. Females usually have dark flanks and pale dorsolateral streaks best developed on the neck, and they can have a dark vertebral stripe or a stripe broken into a series of spots. The vertebral and lateral stripes may be masked to some degree by light spots or may even be absent. Males typically have a more complex colouration and pattern with spotted sides and boldly marked back. The ground colour of the belly may be pale white to cream with varying amounts of red, pink, or rusty-orange mostly in males. The throat usually is white to cream coloured with some rusty and black pigment. Juveniles look like copper to grey-brown coloured females and lack green colouration; this different colouration may serve to limit within-species aggression and competition.

Confusing Species
The few lizard species in Canada are distinctive and easily identified. The only lizard in Canada resembling Wall Lizards in overall structure is the Northern Alligator Lizard, which has large plate-like scales on its back, bead-like scales in a row along the flank and tends to be coppery to brown-grey coloured with dark peppering. Wall Lizards have minute bead-like scales across the entire back and flanks, and while young are brassy to copper-coloured, adults have darker colouration alternating with bright green mottling on the back and sides. Some people in the Saanich area mistakenly call wall lizards 'geckos' - probably because of the Wall Lizard's habit of climbing walls, and like tropical geckos, they live on or near human habitation.

Distribution
Wall Lizards are endemic to continental Europe and western Asia. They have been introduced to several locations in southern England and North America. In the early 1970s, a small group of Wall Lizards was released in west Saanich on Vancouver Island when a private zoo closed. Initially, the lizard population remained small, but once acclimated to our local climate and a breeding population established, the population grew enormously. They now number in the thousands. For the moment, Wall Lizards are restricted to the area of west Saanich, Triangle Mountain in Metchosin, and Victoria on southern Vancouver Island. Recent reports of individuals in the Gorge area of Victoria in 2007, and occasional reports - so far unsubstantiated - of individuals on some islands in the Strait of Georgia, suggest that the species is slowly dispersing. It probably is only a matter of time before Wall Lizards reach the British Columbia mainland or north-western United States, either intentionally or accidentally; southward dispersal is very likely on the mainland.

Habitat
Wall Lizards commonly are found under cover and scatter when their shelter is moved. On Vancouver Island they are associated with human habitation, rock piles, fence rows, and bridges where artificial habitat creates complex structure. In recent years Vancouver Island Wall Lizards have spread into grassy habitat - perhaps because structure around human habitation is saturated and competition within the species is forcing lizards to explore new environments. Wall Lizards also are dispersing thanks to human assistance (i.e., released or escaped pets, or in horse trailers and hay bales).

Reproduction
Females on Vancouver Island lay clutches of 3-8 eggs per summer, and gravid females are found from May to July. In Ohio, they may produce up to three clutches of 4-5 eggs, but there is no evidence of multiple clutches from Vancouver Island. Eggs are deposited under cover, in shallow burrows, and females may even nest communally. Up to 65 eggs have been found together in west Saanich and communal nests appear to be re-used each year. Eggs incubate for 9-11 weeks and hatch in September or October in northern Europe, although on Vancouver Island, hatchlings appear in late July, ranging from 19-25 mm SVL.

Natural History
Wall Lizards are active predators, feeding on small invertebrates such as spiders and a range of insects. They also eat their own young and eggs in captivity, but cannibalism has not been demonstrated in the wild in British Columbia. If attacked, a Wall Lizard's tail will break off at a fracture plane. The twitching tail distracts a predator while the lizard escapes. Many have damaged/regenerated tails as evidence of previous attacks by garter snakes, crows, gulls, hawks, house cats or herpetologists. A new tail eventually regenerates but is never as nice as the original.

Wall Lizards are extremely agile and move in short bursts followed by long pauses to scan for food, rivals, predators, or mates. Males fight for territory and their home ranges usually overlap with those of several females. In Northern Europe, home ranges are between 15-25 m2. Non-breeding satellite males seem to be tolerated in the territory of a breeding male, but intruders which try to establish breeding territory are not tolerated and are driven off. It appears that only territory holders breed in European populations; this may also be true in Vancouver Island populations. Smaller satellite males are just as successful at establishing themselves in vacant habitat as are larger intruding males; it is suggested that habitat (basking site) familiarity gives smaller satellite males an advantage over larger intruders.

In Europe the hibernation period is short, and on Vancouver Island and in England, Wall Lizards may be active throughout winter on sunny days. Wall Lizards have limited tolerance to freezing, and must seek hibernacula below the frost line for extended cold periods. Wall Lizards in northern Europe have slower growth rates and live longer than lizards in southern populations. Body size and growth characteristics of Vancouver Island Wall Lizards does not differ significantly from those of European populations.

Conservation Concerns
At the moment, we do not know whether wall lizards are impacting the native Northern Alligator Lizard (Elgaria coerulea), except that Alligator Lizards are known to avoid cover which is occupied by Wall Lizards. We also do not have any estimate of the Wall Lizard's impact on our native insects and spiders, nor the species composition of the Wall Lizard's diet.

The main concern regarding Wall Lizards is to limit the spread of the species, because eradication will be very difficult given the number of animals now on Vancouver Island. Many land owners enjoy Wall Lizards on their property as a form of "chemical free insect control". Therefore, it is likely that any eradication programme would meet with resistance.

So far the Wall Lizard's range is restricted on Vancouver Island, but it is slowly spreading, and they have the potential to spread far south along the coast if they are released on the Lower Mainland or in Washington. Many of the Gulf Islands also present favourable habitat for Wall Lizards. As with all exotic species, it is far easier not to release exotics, than to try control them later once established.