Lacerta agilis Linnaeus, 1758

Common Name & Taxonomy

This species, Lacerta agilis, commonly called the sand lizard, is a sexually dimorphic legged lizard.

Range & Color Variation

Across its range in Europe and Russia, sand lizard coloration varies.

Marking Patterns

In northwest Europe, both sexes have dorsal and lateral rows of ocellated, eye-shaped markings: dark patches with pale centres.

Male Breeding Coloration

Males have finer markings than females; during the spring mating season, their flanks turn bright green, which fades again by late summer.

Body Length

Adult males can reach a total body length of 19.3 cm, while adult females can reach 18.5 cm.

Western Subspecies

The two main western subspecies are L. a. agilis and L. a. argus.

Western Subspecies Dorsal Stripe

In these two subspecies, the dorsal stripe is thin and interrupted, or absent entirely.

L. a. argus Color Phase

L. a. argus also has a plain red or brown-backed phase with no dorsal markings.

Western Subspecies Breeding Color

In these western subspecies, only males' flanks turn green during mating season.

Eastern Subspecies Coloration

In the predominantly eastern subspecies L. a. exigua, males can be entirely green even outside the breeding season.

Defense Mechanism

Sand lizards can self-amputate their tails for defense, an ability called autotomy.

Male Coloration & Fitness

In males, brighter green genital coloration correlates with higher body mass and greater fighting ability; males with brighter coloration are more likely to initiate aggressive behavior and win fights, which typically gives them higher mating success.

Female Appearance & Reproductive State

Females are usually grey to brown in color, and can be seen with large bulging bellies full of eggs between May and August.

Lifespan

Sand lizards can live for over ten years, with an average lifespan of 5 to 6 years.

General Habitat Preference

Sand lizards occupy a variety of habitats, and prefer dry habitats including outcrops, fields, hills, beaches, heathland, sand dunes, and rock gardens.

Continental Europe Habitat

In continental Europe, the sand lizard uses a wide diversity of habitats.

UK Habitat Restriction

In colder locations like Great Britain, sand lizards depend on sand to incubate their eggs, so they are restricted to coastal habitats.

Male Home Ranges

Male sand lizards have home ranges with extremely high overlap.

Female Home Ranges

In contrast, female sand lizards have much smaller home ranges, generally less than 100 square meters, that adjoin each other, and females may even share burrows or basking areas with one another.

Microhabitat Preference

Sand lizards strongly prefer and are most active in areas with a wide range of structural characteristics, which create different temperature microhabitats they can move between to match their needs.

Sexual Maturity Size

Males generally reach sexual maturity at a smaller size than females.

Female Vitellogenesis Period

For the entire population, vitellogenesis in females takes 45 days.

Mating Period Energy Use

Both sexes tend to lose body fat during the mating period, as they draw most of their energy from body fat stored in the liver and proximal portion of the tail.

Post-Hibernation Male Behavior

A few weeks after emerging from hibernation, adult males become extremely aggressive toward each other, and attempt to mate with as many females as possible.

Egg Laying Site

Female sand lizards lay eggs in loose sand in a sunny spot, leaving the eggs to be incubated by geothermal warmth.

Clutch Frequency & Size

Most females lay only a single clutch each year, with clutch sizes ranging from six to 15 eggs per clutch.

Egg-Laying Timing Variation

There is substantial variation in the time of year females lay their eggs, but individual females typically have relatively consistent egg-laying timing from year to year.

Female Fitness & Egg-Laying Timing

Larger, more physically fit females generally lay eggs earlier than other females.

Clutch Timing & Offspring Quality

Early clutches produce larger offspring that are more successful and have higher survival rates; overall, offspring from earlier clutches are higher quality.

Clutch Size & Offspring Size Tradeoff

When a female sand lizard produces a larger clutch size, each individual offspring in the clutch is smaller. Conversely, smaller clutches produce fewer but larger offspring.

Resource Availability & Clutch Size

When food resources are increased and no longer a limiting factor, clutch size increases significantly.

Clutch Size Adjustment

This suggests sand lizards adjust clutch size and individual offspring size based on available resources.

Clutch Size Physical Constraints

Physical constraints on the space available for clutches are an additional contributing factor.