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Emerald Swift Care

Emerald Swift Care

Emerald Swift Care


The emerald lizard, Lacerta bilineata, is exceptionally up to 42 cm long and is without doubt the largest, but also the most beautiful lizard species in Switzerland. The average length of adult lizards is between 25 and 32 cm.

The sexes are generally easy to distinguish externally. The males are stronger than the females, their head is more massive and larger, and their throat becomes bright blue at reproductive time. Also single females sometimes have a blue throat, but the colouring remains always less intensive. The back coloration of the males is bright emerald green, interspersed with fine yellow and black speckles. The females are more variable. Some are almost grey with symmetrically distributed black spots, others are also green.

The belly side of the males is bright yellow, that of the females pale yellow to greenish. Freshly hatched young have a monochrome grey to brown upper side. Neck and lower jaw are yellow-green, the belly side dirty-white. In the second year, two light longitudinal stripes appear on the flanks, which sometimes remain in the females. Black emerald lizards are rarely seen in Switzerland. Adult animals weigh between 20 and 45 grams.


Around mid-March, the first males leave their winter quarters and expose themselves to the sun. About two weeks later the females follow. The emerald lizard is diurnally active and its activity rhythm is strongly temperature-dependent.

During the hottest days it is only active in the morning, often before the wall lizards, with a maximum between 9 and 11 o'clock. In the afternoon the activity remains limited. The species prefers to move on the ground, but also climbs on lower branches in cool weather for sunbathing. After sunset they are often seen on warm stones. The minimum temperature tolerated outside the hiding places is 15 °C, the preferred range is between 32 and 33 °C. The temperature of the rocks is between 15 and 33 °C. The wintering grounds are visited around mid-October, first by the females, followed by the males and the young.

Emerald lizards are faithful to their habitat and the males often defend a territory of 200 to 1,200 m2. In Valais, we have counted up to 45 adult animals per hectare in optimal habitats, which is about 220 m2 per lizard. At the age of two, most individuals are sexually mature. The reproductive period is from April to mid-June. The males hunt each other noisily in the vegetation. Their courtship fights are fierce. The winner often hunts the loser over longer distances. Also among the females, a hierarchy exists.

The beginning of the combination is ritualized: The male bites the female into the tail root and then into the flanks and finally holds it with the front legs. A male can fertilise several females, and the latter also mate several times before egg deposition. A female can lay eggs twice a year. The first laying usually takes place at the end of May, the second at the end of June.

The 5 to 15 eggs are buried little deep in loose sand, loam or loess soil, often in the evening or even at night. Depending on weather conditions, the 3 to 4.5 cm long young animals hatch after 50 to 100 days and then often fall victim to adults. The lifespan of the species is 5 to 15 years.

The food of the emerald lizard is varied, but mainly consists of arthropods such as beetles, grasshoppers, caterpillars, isopods and spiders, as well as snails with thin-walled houses and ripe berries whose juice the animals lick up. Occasionally, newborn lizards and mice are also eaten. The emerald lizard often drinks, in the form of dew drops or in summer from water holes. It has numerous enemies. In Valais we have seen kestrels, which specialise in lizard catching and have often brought the animals to their nests. Around Geneva and in Ticino, the Zorn snake is the main hunter of emerald lizards. Young animals are eaten by young vipers. In the settlement area the domestic cat is the main enemy. Their patience can handle even the most attentive individuals.


In Valais and Ticino, the species is not yet threatened thanks to large population reserves. Nevertheless, many of its habitats are being devastated by intensive farming. The highest densities are observed on lower and middle slopes. There are few suitable habitats in the cantons of Geneva and Grisons, which therefore require special attention.

In the canton of Vaud, the emerald lizard is under the greatest threat: in Chablais, land consolidation in the vineyard area is destroying many of the already fragmented habitats. The situation of the species on the shores of Lake Geneva gives rise to pessimism: between Geneva and Montreux there are just two to three small and completely isolated populations! In general, the emerald lizard is most endangered in the vineyards. This is where species protection comes into conflict with agriculture.

The following measures can favour the survival of the species or even population growth:

  • Restrict land consolidation in the vine area or have it accompanied by reptile experts.
  • Create buffer zones at least three metres wide around vine plots. These should end with a herbaceous border and should not pass directly into the vineyard.
  • Only in winter should slopes be cleared and alternated between cultivated and pristine sectors every two or three years.
  • Railway and road kerbs, forest edges and embankments are preserved as connecting corridors between habitats. At the edge, fallow strips are created. Where reptiles are present, suggest to the responsible officials the creation of stone heaps and stocking with native bushes.
  • Stop helicopter spraying flights in vine areas, as important small areas cannot be spared and existing food chains will be interrupted for longer periods.
  • Remove stray domestic cats in the settlement area.
  • Do not use wild fires in agriculture because they destroy many insects as a food source.
  • To massively limit the use of chemicals in areas with high reptile density.
  • Protect clearings and abandoned cultivated land from forest management.
  • Inform winegrowers about the importance of lizards in the food chain and as insect killers.


Male frontal lobe basilisk (Photo: SWR)The frontal lobe basilisk belongs to the reptiles and there to the iguanas family and to the genus basilisks. Its typical characteristic is the small frontal lobe and the large occipital lobe. This is also called the head sail, because it protrudes backwards from the head like a sail.

On the middle of the back, skin combs stretch along from the head to the tail. They are supported by bone braces and can reach a height of up to five centimetres.

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Female basilis of the frontal lobe on a branch (picture: SWR)Her physique resembles that of an iguana. The animals grow up to 70 centimetres long, some even longer. However, the tail makes up two thirds of them. It reaches a length of 50 to 55 centimeters. The four legs are strong. Like all reptiles, the basilisks of the forehead lobe skin themselves regularly.

The skin scales of the frontal lobe basilisks are emerald green, dark green or blue-green. On the belly-side, they are somewhat lighter, at the back, they carry a yellow until bluish Sprenkelung.

Female basilisk of frontal lobe on a branch (Photo: SWR)The skin combs on the back and frontal lobe of females are much less pronounced, and the back of the head is much smaller than in males.

However, these differences between males and females only become apparent at the age of seven to twelve months.

Before that, the animals are hardly distinguishable.


Forehead lobe basilisk (picture: SWR)Forehead lobe basiliskas are tropical inhabitants.

They live in shady rain forests and wetlands up to 25 metres above sea level.

There they live mainly on trees. It is important that the trees are close to bodies of water.

The animals are rarely found on the ground.

Breeds and Species

There are five different basilisk species in tropical Central and South America.

In addition to the frontal basilisk, these are the helmet basilisk, which occurs in Central America, Colombia and Venezuela.

The Ecuador basilisk lives from Costa Rica to western Colombia and Ecuador.

The Crown Basilisk lives in the forests from southeast Mexico to Nicaragua, the Strip Basilisk lives from southern Mexico to Colombia.

Life expectancy

In captivity, forehead lobe basilisks can live up to 15 years if well cared for. In nature they usually die much earlier, probably at the age of eight. Females generally live less long than males.

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