Wall Lizards, Rock Lizards, and Relatives: Lacertidae

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WALL LIZARDS, ROCK LIZARDS, AND RELATIVES: Lacertidae

SAND LIZARD (Lacerta agilis): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

The wall and rock lizards, and their relatives, are small to medium-sized lizards with strong legs, especially the larger back pair, and usually very long tails. The typical wall or rock lizard has small beaded scales on its back and large square or rectangular scales on its belly. They come in many different colors and patterns from an almost entirely green or drab brown body to a bluish body with black blotches, a body split into a red front and black-and-white speckled back, or a black and cream striped body and red legs. Some species have brightly colored tails, which attract the attention of predators (PREH-duh-ters), or animals that hunt them for food. Fortunately, the lizards can easily drop their tails if they are attacked, allowing the lizard, minus its tail, to escape. In many species, the males have more spectacular colors than the females, and males in some species become even more brilliantly hued during the mating season.

The average adult grows to less than 8 inches (20 centimeters) long from head to tail, although a few species in this large family can reach 20 inches (50 centimeters) in length. Of their total length, much can be tail. In some species, such as the oriental six-lined runner, three-quarters of their overall length is tail.

GEOGRAPHIC RANGE

Wall and rock lizards live in Europe, Asia, Africa, and the East Indies.

HABITAT

Wall and rock lizards are very common in dry areas, such as deserts, but some species make their homes in forests or in very cold areas, such as grasslands high up in the mountains or in far northern lands inside the Arctic Circle. They are also found on some Atlantic Ocean islands, including the Canaries off northern Africa, Sri Lanka (or Ceylon) off the southern tip of India, and the British Isles.

DIET

The bellies of these lizards are usually filled with insects, which they typically capture by sitting very still in one spot— usually in the shade—until an insect wanders by. They then spring out and grab the tasty morsel. This type of hunting is called ambush. The western sandveld lizard is unusual because while it eats some insects, its main diet is scorpions, which the lizard finds by looking for their tunnel entrances and digging them out of the ground. Some species in this lizard family also eat seeds and fruit in addition to insects. A few, including the adult giant lizards that live in the Canary Islands, are unique in that they eat almost only plant material.

BEHAVIOR AND REPRODUCTION

Active during the day, wall and rock lizards typically like to sunbathe, or bask, to warm up their bodies. Most of them bask out in the open on rocks or on the ground. Some, such as Asian grass lizards, climb into plants and bushes and use their very long tails to wrap around stalks and branches. A few species, like the western sandveld lizard, stay in underground burrows most of the time.

Usually the lizards are able to avoid predators by keeping careful watch and running for cover before an attacker can come too close. The shovel-snouted lizard is even able to dive into the sand of its desert home and bury itself. This lizard scoots even deeper when it wants to take a cool and safe nap. Young Kalahari sand lizards have another defensive tactic. These baby lizards look so much like a bad-tasting beetle, known as the oogpister, that predators avoid them. Despite these behaviors, however, attackers are sometimes able to approach wall and rock lizards closely enough to attack them. When this happens, a wall or rock lizard can drop its tail, leaving the tail for the predator while the lizard escapes. A replacement tail grows, but it is usually much shorter.

Almost all the lizards in this family lay eggs and usually fewer than ten at a time. A female digs a hole in the ground and lays her eggs there. In many cases, the mother digs the nest under a rock that is out in the open and can warm up in the sun. The underground soil keeps the soft-shelled eggs moist. She then leaves the nest; the eggs hatch later, and the young are on their own. The largest females lay the most eggs, with some female eyed lizards giving birth to twenty eggs at a time. The females of a few members of this family have baby lizards rather than eggs. This includes the viviparous (vie-VIH-puh-rus) lizard, which lives in northern Europe. Females of this species mate with the males in the spring to early summer and have four to eleven babies three or four months later. Seven species in this family are all females, but they can still have babies, which are also all females.

WALL LIZARDS, ROCK LIZARDS, THEIR RELATIVES, AND PEOPLE

People usually leave these lizards alone, but long ago, some humans hunted and ate the giant lizards of the Canary Islands.

CONSERVATION STATUS

According to the World Conservation Union (IUCN), Simony's giant lizard is Critically Endangered, which means that it faces an extremely high risk of extinction in the wild. This giant lizard is so rare that scientists actually thought it was extinct until a small population turned up in 1975 high in the cliffs of El Hierro, one of the Canary Islands. Another species, called the Gomeran giant lizard, was similarly thought to be extinct until 2001 when a population was discovered in the Canaries. It may be even more rare than Simony's giant lizard, but the IUCN has not yet listed it as being at risk. The greatest predators to these lizards are cats and rats, which were both brought to the islands by humans.

A LOSING TAIL

Many lizards, including the wall and rock lizards of the family Lacertidae, can drop their tails when they are attacked. The dropped tail wiggles around on the ground and draws the attention of the attacker while the lizard runs for its life. Wall and rock lizards can drop their tails because their tails are made of a series of small bones that have weak points between them. The lizard also has a ring of strong muscles around each weak point. When attacked, the lizard squeezes the ring of muscles so tightly that the weak point in the tail snaps and the tail falls off. After it drops, nerves in the tail continue to work sometimes for many minutes, and the tail busily squirms along the ground. Eventually, the tail stops moving, but by then, the lizard is long gone.

In addition to Simony's giant lizard and the Gomeran giant lizard, the IUCN has listed Clark's lacerta as Endangered, which means that it faces a very high risk of extinction in the wild, and five others as Vulnerable, which means that they run a high risk of extinction in the wild. The U.S. Fish and Wildlife Service lists the Hierro giant lizard as Endangered, or in danger of extinction throughout all or a significant portion of its range, and the Ibiza wall lizard as Threatened, or likely to become endangered in the foreseeable future.

SAND LIZARD (Lacerta agilis): SPECIES ACCOUNT

Physical characteristics: One of the larger members of this family, the biggest sand lizards can grow to almost 12 inches (30 centimeters) long from the tip of the head to the end of their long tail. Most, however, reach only about 8 inches (20 centimeters) long. In the eastern part of its range, the sand lizards may be greenish, but western lizards are usually brown or gray with dark spots and/or stripes. Males of the western sand lizards also show some green along their sides and on their bellies and become brighter green during the mating season.

Geographic range: The sand lizard lives in spotty areas throughout Europe and Asia, from the British Isles to China, and as far south as Greece.

Habitat: The sand lizard is common in places with sandy soils, such as sand dunes and brushy areas, but it can also make its home in clay-type soils along forest edges and in fields and gardens.

Diet: It lives mostly on insects, which it hunts by looking for them while skittering through cover in its habitat. It will also sometimes eat worms and other invertebrates (in-VER-teh-brehts), which are animals without backbones, as well as fruit and flowers, and once in a while even another sand lizard.

Behavior and reproduction: The sand lizard is active during the day and will run through brush above ground or bask in warm spots, but it usually stays out of sight. This shy lizard often darts into holes or tunnels it finds among plant roots when it feels the least bit threatened. Numerous sand lizards may live together in the same area. In colder climates, they will hibernate from fall to early spring.

During the breeding season in the spring, the males turn into fighters and will battle one another over the chance to mate with a female. The fights usually involve the males grasping each other's necks, and then wrestling until one gives up and leaves. After mating with a male, a female finds a sunny spot where she digs a hole and lays three to fourteen eggs. She provides no care for the eggs or her young. In forty to sixty days, the eggs hatch.

Sand lizards and people: Humans and this lizard rarely see one another.

Conservation status: Although neither the IUCN nor the U.S. Fish and Wildlife Service list this species as threatened, some populations are at great risk because of the destruction of their habitat. In western Europe, the lizards typically live in heathlands, which are open areas covered with low plants and shrubs. When the heathlands are destroyed to make way for homes or other human development, the lizards disappear. ∎

FOR MORE INFORMATION

Books:

Behler, John, and F. Wayne King. "Typical Old World Lizard Family (Lacertidae)," National Audubon Society Field Guide to Reptiles and Amphibians. New York: Alfred A. Knopf, 1979.

Böhme, W., ed. Handbuch der Reptilien und Amphibien Europas. 2 vols. Wiesbaden, Germany: AULA Verlag, 1984–1986.

Branch, B. Field Guide to the Snakes and Other Reptiles of Southern Africa. Capetown, South Africa: Struik Publishers, 1998.

Burnie, David, and Don Wilson, eds. The Definitive Visual Guide to the World's Wildlife New York: DK Publishing, 2001.

Halliday, Tim, and Kraig Adler. The Encyclopedia of Reptiles and Amphibians. New York: Facts on File, 1986.

Mattison, Chris. Lizards of the World. New York: Facts on File, 1989.

Valakos, E.D., W. Böhme, V. Perez-Mellado, and P. Maragou, eds. Lacertids of the Mediterranean Region: A Biological Approach. Athens, Greece: Hellenic Zoological Society, 1993.