Surrey Amphibian and Reptile Group (SARG) 

Western Green Lizard

  

Nomenclature

Common name:  western green lizard 
Taxonomy:  Lacerta bilineata (Previously Lacerta viridis) (Laurenti, 1768)
Other Names:  Green lizard
European green lizard

Introduction

This non-native continental species is a large and magnificent lizard, famous for its splendid green colouration and imposing size.

It favours dense vegetation in sunny sites, although on the continent these may be very varied including dune systems, heaths and wood edges in particular.

In the UK is a very local species indeed. There is just one known surviving introduced colony in mainland Britain but the lizard is also native to the channel islands.

These spectacular lizards seem to have potentially competed detrimentally with common lizards at Bournemouth although this is difficult to judge given the large amount of the more aggressive wall lizards on the site which is probably responsible for much of the damage. It remains to be seen whether this trend continues across other sites. It is indeed an illegal alien invader and its excessive spread should be actively discouraged. However, we can also be thankful and delight that such a magnificent member of the European herpetofauna can be found in isolated areas of the UK for us to enjoy.


Identification

A large, elegant, robust lizard with a broad and deep head. Adults should be unmistakeable due to their large size (up to 40cm) and brilliant green colouration.

The channel islands populations tend to be more heavily marked than the more uniform Bournemouth examples. This is probably because the Bournemouth lizards have been introduced by examples far into their continental range. It has been suggested that their DNA is most similar to examples from northern Italy near the Slovenian border.


Morphology


Sexual Dimorphism

There is a strong sexual dimorphism exhibited in this species.

Males are to a great extent entirely green albeit peppered with fine black spots. The head is darker green with a bright blue throat in mature individuals that is more intense in the spring. Males are also stockier, often a larger size and have a broader head.

Females are smaller with a lighter build and a more narrow head. Their colouration is also more variable, they tend to be less vividly green and may even have an entirely brown back. They often possess two or four narrow light cream or white lines that run the length of the body. Some older females may also develop a blue throat but this is rare.


Could be mistaken for

As an adult it is a markedly different species from our other lizards and a full view of a mature individual should leave the observer in no doubt of its identification. A glimpse of a smaller specimen however could be confused with any one of our legged lizard species.

The sand lizard is a close relative with a similarly robust build and relatively large head, the males are also green although only in spring. However, even the most green male sand lizard will never be as verdant as even a dull female western green lizard. The sand lizard always has a brown back which is only an uncommon variety in some female western green lizards. Even in this rare case extremities such as the top of the head and the tail of the western green lizard remain green – parts of a sand lizard that will never be green in the UK.

In both Bournemouth and parts of Jersey the western green lizard is also found alongside the wall lizard. The wall lizard is a very variable species with a common green form. However, the green exhibited here is at most a dappled and irregular infusion of colour – mainly along the back. Even in 'green form' one would be forgiven for calling the wall lizard largely a brown lizard. The mottled patterns of the wall lizard are very different to the patterns of a mature adult green lizard. The vast differences in build should be diagnostic.

The common lizard is a markedly different animal from the western green lizard and although they to possess a green form they remain heavily marked animals that a fraction of the size of western green lizards. Again the differences in the build of the two species should make them difficult to confuse.These differences are less marked in the juveniles. (See below).


Distribution

Native distribution for western green lizard © seh-herpetology.org

The western green lizard enjoys a relatively widespread distribution although restricted to western Europe. It can be found in northern Spain, the vast majority of France (absent from south north-eastern areas), Italy (including Sicily), and southern Slovenia. There are also isolated populations in Germany and Switzerland. It is not native to the British Isles but it is native to the channel isles.

With this in mind the UK populations occupy a tiny percentage of its world range. Significant known introductions have occurred in Devon (Paignton 1937-46), Surrey (Haslemere 1905-10), North Wales (Ynesneuadd woods 1872), the Isle of Wight (St. Lawrence 1899-1946), Gloucestershire (1960s), Co. Clare in Ireland (Burren n/a) and Kent (Sittingbourne 1962) probably among many others. The only viable population known currently is the Bournemouth colony. This has only been known since 2003 although unconfirmed reports of the lizards in the area go back as far as 1996. The colony occupies a small area of the coast to the east of the town mainly centred around Boscombe cliffs. The colony is both breeding and spreading however, it is not unusual for such colonies to persist for many years before reaching a natural extinction. For example the large introduction of 230 lizards at St Lawrence on the Isle of Wight which was introduced in 1899 persisted to at least 1936 before eventually reaching extinction. For the moment the Bournemouth colony appears to be doing very well.

The lizard is native to the channel islands, although Jersey enjoys almost all the colonies. It is particularly associated with the extensive stabilised dune systems in the west of the island. Typical areas include the stronghold of Les Blanches Banques reserve. It has recently been successfully introduced to Guernsey.

In Surrey a historic introduction was attempted at Haslemere, which persisted for five years from 1905 until 1910.

UK distribution for western green lizard © NBN
UK distribution for western green lizard © NBN
There are no recorded sightings of western green lizard in Surrey
There are no recorded sightings of western green lizard in Surrey

Habitat

At Bournemouth the western green lizard inhabits the scrubby grass and heath at the top of the steep south facing Boscombe cliffs. In Jersey the western green lizard is most common at the coast, especially on the west of the island where it favours dunes and coastal grassland. Elsewhere in its continental range it is also found in hedges, wood edges and in southern Europe it is particularly common in wet areas, e.g. I observed many in thick sedge beds in Sicily. Within such habitats it needs dense, bushy vegetation, with open areas that have good basking potential, e.g. bramble thickets, mature heather, mature marram grass etc. It possesses a marked preference for south facing slopes, especially in the northern part of its range.


Activity

Western green lizards hibernate in October and emerge during April, although a few emerge in late March. The lizards mate in late April and early May, when the animals are most territorial, colourful and easily approached.

These diurnal, sun-loving animals are fond of basking deep in vegetation and are extremely nervous which makes approaching them difficult. Examining likely basking spots such as clearings in mature heather or a break in dense bramble scrub gives the best opportunity for observation. Remember on Jersey and Guernsey, western green lizards are strictly protected.

When disturbed these lizards will make a significant commotion, especially a mature adult, however, the lizards use regular basking locations and a return to the site of the disturbance will often prove to be profitable. If an area supports one individual then it is more than likely that others may be found in the surrounding immediate areas and examination of nearby appropriate habitat is often worthwhile.


Food

The western green lizard in general takes much larger prey than our other lizard species. It also arguably has a much wider variety of food types than other UK lizard species, The main food source is insects (often rather large), spiders, slugs and worms. More occasionally the western green lizard will also eat fruit, eggs, nestling birds and young reptiles.

Within the Portman ravive at Boscombe, it can be entertaining watching these large lizards jumping high out of the vegetation to catch passing bees.

Slug
Slug
Earthworm
Earthworm
Cricket
Cricket

Predators

The predator of this lizard in the UK have not been studied, but it is likely that they include domestic cats, foxes, badgers, raptors and corvids. It is also likely that rats will prey upon burried eggs.

Domestic cat
Domestic cat
Buzzard © Marek Szczepanek (GNU)
Buzzard © Marek Szczepanek (GNU)
Brown rat
Brown rat

Shelter

Western green lizards hibernate in underground burrows. Most often using mammalian burrow systems.

They favour sheltering in their beloved dense vegetation above all else although they will also use logs, woodpiles and stones. Like all of our lizards, western green lizards will make use of man-made shelters such as roofing felts, wooden planks, sheets of corrugated iron, beach flotsam etc.


Reproduction

In their breeding season (late April to mid May) males will compete very aggressively for females. It is the larger males who will usually win these contests and father offspring. The eggs are laid about a month after mating (mid June to mid July and bare sand is required for this purpose. Clutch sizes vary widely depending on the size of the female and ranges from 5 to about 20 eggs. This lizard's relative fecundity is clearly far higher than our native lacertid lizards although this is only to be expected with a lizard of greater proportions.


Juveniles

Juvenile western green lizards emerge from their burrows in late August throughout September and exceptionally in early October. This means that they may not even have a meal (like some of our juvenile reptiles) before their first hibernation. Nevertheless when the opportunity arises juveniles are voracious predators of invertebrates.

Hatchlings are a fairly uniform light brown or beige usually with a few light markings such half a dozen or so spots, or two or four narrow light lines along the body from the neck to the tail The hatchlings measure 7-9cm in total length (3-4cm snout to vent). In their first year the hatchlings usually turn an olive green with a characteristic brighter green head. These animals possess the same distinctive uniformity and often retain the lines along the length of their body if present. These lines become less broken and more prominent during this year of life, however, not all examples have these markings. Adult colouration is acquired from the second year of life and many females will breed in their second spring.

The juveniles once familiar are distinctive. However, the hatchlings in particular may easily be mistaken for other reptiles - especially if a clear view is not gained.

The wall lizards that coexist alongside it at Bournemouth and many Jersey sites, let alone much of its continental range tend to have much heavier patterning and are never as uniform as a juvenile western green lizard. Even at a young age the habitat preferences of these lizards are opposing: the wall lizard favouring rocky habitat such as walls, quarries, cliffs etc. whereas the western green lizard will usually favour dense vegetation.

Sub-adult common lizards may be similarly problematic but again possess far heavier markings. Juvenile common lizards are unlikely to be confused due to their comparatively diminutive size and very dark colouration.

It is juvenile sand lizards, however, that have the most similar markings and build. These slightly smaller hatchlings tend to be a deeper brown and although display light spots, these spots are more numerous and they are edged black (western green lizards will never display this characteristic), additionally the spots are always present. There may also be a poorly developed light dorso-lateral striping but it is rarely continuous and is always accompanied by the distinctive black edged spots.


Conservation

At present the only known colony is the Bournemouth population (2003 onwards). These lizards are breeding successfully and spreading along the cliffs. There are no conservation measures to conserve the lizard at Bournemouth.

In Jersey where the lizards are native, many colonies have been lost to agriculture and development. Conservation effort focused on habitat management and protection has proved effective and the remaining populations are thriving. Introductions to the island of Guernsey have also been successful. As long as management continues, legal protection and habitat is preserved, there are no threats to the survival of the species.



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Information

Principal Author(s):Main Illustrator:Edited by:Updated:
Henry WilsonSteve Langham07 Sep 2018