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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.
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