Species Information:
Common Wall Lizards are small slender lizards, with snout-vent lengths up to 7.0 cm, and with a complete tail, they can range to 21 cm long. Most are much shorter because of tail damage (caudal autotomy and regrowth). The distinctive characteristics of adults are their bright green wash of colour most prominent over the neck, shoulders and back, and the green colouration is interrupted by a network of coppery brown to black pigmentation. The tail is long and slender, legs are fairly long as are their toes, and the scales on the back are minute. Their colour is variable but ranges from green to coppery brown, with young wall lizards starting out copper brown with darker lateral stripes. As they mature, green colouration develops, as does the network of darker patterning on the back. Males have more robust jowls, colour often is more bold, and they have a V-shaped series of pores on the underside of the pelvic region extending onto each thigh. Females are more lightly built, and lack the obvious pores along each thigh.
Biology
Reproduction
Mating occurs from March to May, and may occur later in the summer. Females lay 2-11 eggs, which hatch in mid-to late summer, sometimes into October. It appears that adult females can produce two clutches of eggs a season, and in long warm years may produce three clutches although this has not been demonstrated in British Columbia. Common Wall Lizards nest singly or in communal nests.
Diet
Common Wall Lizards feed mostly on small arthropods. They have been seen eating a range of insects including aphids, ants, termites, earwigs, wasps, mason bees, and bumble bees. Wall Lizards eat dried earthworms, and are known cannibals, taking conspecifics about 2/3rds their own length. They have been observed killing newborn garter snakes, and presumably can eat them. In Europe, the related Italian Wall Lizard (Podarcis siculus) was observed attempting to eat a shrew, and so newborn mice and shrews are possible as prey items for the similar sized Common Wall Lizard. Wall Lizards also take fruit, including blueberries, raspberries, blackberries, tomatoes, and ripe wind-fall figs.
Behaviour
Common Wall Lizards are skittish and dive for shelter when approached. They use any available basking site, and where basking sites are limited, are known to pile on top of each other to get the best sun exposure. From spring to autumn, Common Wall Lizards are active throughout the day, although may take shelter mid-day to avoid the most intense heat.
Wall Lizards are territorial and fights occur between rivals for optimal habitat. These fights may including biting, but most often, lizards simply chase a rival away. Mating pairs may be found in close association early in the year, but later in the year they seem to part company.
Hatchlings seem to occupy different habitat than adults, likely as a result of predation risk. Hatchlings disperse into grassy areas to avoid adults and later in life move to rock walls, wood piles, or other structure to establish territory.
Seasonal Characteristics
On southern Vancouver Island, common wall lizards can be active year round in sunny weather. They have been observed every month of the year, but are more prevalent from March to September. In winter they can be seen in sun-exposed areas exposing their heads from crevices. Lizards caught at 5°C air temperature feel warm to the touch because of effective basking behaviour.
Habitat
Common Wall Lizards frequent disturbed habitat, road cuts, railway thoroughfares, cemeteries, gardens and take advantage of warm south-facing slopes and rock walls, especially during the cooler weather in spring and fall. They can become super abundant in urban and suburban gardens as well as in farmland where open rock walls, firewood piles, fences, decorative driftwood, and more formal brick and cinder block walls provide basking habitat and quick refuge when predators approach. Common Wall Lizards have adapted to garden irrigation systems as convenient water sources. With increasing population density, lizards have started to move into more natural habitat, including grasses, and are known to climb trees in search of basking opportunity.
Distribution
The native range for the Common Wall Lizard extends from Spain, France and Belgium in western Europe, east to Romania, Bulgaria, Greece and western-most Turkey.
Common Wall Lizards also are introduced in several locations in southern England and the Isle of Wight. These are thought to be escaped and intentionally released pets and zoo animals, and some arrived in shipments of ornamental plants. The Isle of Wight lizards may have been contaminants in cargo on a wrecked Italian ship or from the pet trade. Common Wall Lizards also have been intentionally introduced in Austria, Belgium, and Germany, but the introduced population in Belgium failed. In the United States, Common Wall Lizards were intentionally released in Cincinnati in 1951, with subsequent natural and assisted dispersal in Ohio, eastern-most Indiana and northern Kentucky, as well intentional introduction in northern Kentucky.
In British Columbia Common Wall Lizards are superabundant on Vancouver Island from Metchosin north to Swartz Bay in the capital region, and in scattered populations up the east side of Vancouver Island north to Campbell River. A large population is established in the Nanaimo region. A single lizard has been seen at Sproat Lake, and on Hand Island in the Broken Group off Ucluelet on the west side of Vancouver Island. A population exists on Denman Island (since 1997), and they were detected on Saltspring Island in 2020, and North Pender Island (2021). There were two attempts to introduce Common Wall Lizards to Summerland in the 1980s, but fortunately, the populations failed. A single lizard was found in Osoyoos in a shipment of grapes from Vancouver Island, but it was captured. Single lizards have been sighted in the Caulfeild-Cypress Park area of Vancouver - along Meadfeild Wynd, but without subsequent reports, these may represent individuals that have since died. In contrast, a population is established in the Vedder Crossing area south of Chilliwack, along Kathleen Drive with hatchling lizards seen in the area in 2020.
Conservation
Common Wall Lizards are exotic to British Columbia and are listed under Schedule C of the Provincial Wildlife Act.
Taxonomy
Based on genetic sequencing and color pattern, Podarcis muralis in BC are attributable to the subspecific taxon maculiventris from the Emilian Apennines, Italy.
Comments
Common Wall Lizards bite when handled, but their teeth are tiny and do no damage to human fingers. They also drop their tails as an anti-predator behaviour – and the re-grown tail never looks the same as the original tail. Regrown tails have different colour and scale patterns compared to the original.
It is illegal to catch and transport, and especially release Common Wall Lizards, but the rapid spread of this species in British Columbia is due to human assistance, either accidental or intentional.
Species References:
Allan M, Gregory P, Prelypchan C. 1993. The ecology of introduced Common Wall Lizard (Podarcis muralis) in Saanich, Vancouver Island. Victoria, BC: Report to the BC Ministry of Environment. 24 p.
Allan M, Prelypchan C, Gregory P. 2006. Population profile of an introduced species, the Common Wall Lizard (Podarcis muralis), on Vancouver Island, Canada. Canadian Journal of Zoology 84:51–57.
Burke R, Deichsel G. 2008. Lacertid lizards introduced into North America: History and future. In: Mitchell JC, Jung Brown RE, Bartholomew B, editors. Urban Herpetology. Salt Lake City, UT: Society for the Study of Amphibians and Reptiles. p 347–353.
Capula M, Aloise G. 2011. Extreme feeding behaviours in the Italian Wall Lizard, Podarcis siculus. Acta Herpetologica 6: 11–14.
Claussen D, Townsley M, Bausch R. 1990. Supercooling and freeze-tolerance in the European Wall Lizard, Podarcis muralis, with a revisional history of the discovery of freeze-tolerance in vertebrates. Journal of Comparative Physiology B 160:137–143.
Deichsel G, Schweiger S. 2004. Podarcis muralis (Commo
n Wall Lizard). Canada: Britis
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Engelstoft C, Robinson J, Fraser D, and Hanke G. 2020. Recent rapid expansion of Common Wall Lizards (Podarcis muralis) in British Columbia, Canada. Northwestern Naturalist 101: 50–55.
Kraus F. 2009. Alien Reptiles and Amphibians: a Scientific Compendium and Analysis. Invading nature: Springer series in invasion ecology 4. Springer, New York, New York, USA.
Lever C. 2003. Naturalized reptiles and amphibians of the world. Oxford, UK: Oxford University Press. 318 p.
Lever C. 2009. The Naturalized Animals of Britain and Ireland. London, UK: New Holland Publishers. 424 p.
Matsuda B, Green D, Gregory P. 2006. Amphibians and reptiles of British Columbia. Royal BC Museum Handbook. Victoria, BC: Royal BC Museum. 266 p.
Speybroeck J, Beukema W, Bok B, Van Der Voort J, Velikov I. 2016. Field Guide to the Amphibians and Reptiles of Britain and Europe Bloomsbury, London, United Kingdom.
