Reptiles

Vous trouverez ici des informations sur les reptiles que l’on peut observer dans le Léman.

species in the world
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indigenous species around Lake Geneva
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species introduced by humans
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The reptiles of Lake Geneva

You can find out more about the reptiles of Lake Geneva in issue 127 of our quarterly magazine Lake Geneva regionand in our News in 60 seconds (number 192035 and 98).

Introduction

With some 10,000 species worldwide, the reptile class is one of the smallest of the vertebrates. It is divided into 4 orders:

  • Squamates (Squamata)which represents almost all the reptiles living in the Lake Geneva region, including the viperine snake, which lives naturally south of the Alps, and the tessellated snake, a close cousin which has been present since the beginning of the 20th century as a result of human activity.
  • Turtles (Testudines)These include the European pond terrapin (Emys orbicularis), which is the only indigenous representative of this order, and the Florida tortoise, a small aquatic turtle that is particularly popular with aquarists and is unfortunately sometimes released into the environment.
  • Crocodiles (Crocodylia)of which there are no species in the Lake Geneva region
  • the Sphenodontians (Sphenodontia)of which there are no species in the Lake Geneva region


Herpetology is the science that studies amphibians and reptiles.

Reptiles are "poikilothermic" species. This means that their body temperature adapts to the ambient temperature. In winter, reptiles live in slow motion and go into hibernation. In spring, they take advantage of the first warm spells to emerge from their winter torpor. They are often posted in full view on riprap or on a pile of wood in search of the first rays of sunshine. This is the best time to observe them. Later in the summer, reptiles shelter in these same structures to protect themselves from the heat.

Their skin is covered with scales that grow throughout their lives. More or less frequently, depending on the species, reptiles moult by removing the upper part of the scales. Pieces of "skin" are thus detached little by little or in one piece.

Turtles, Crocodiles and Sphenodontians have four legs. Among the Squamates, the question is more complex. This order is divided into several sub-orders, the main ones being the lacertilians and the snakes. Lacertilians have 4 legs (atrophied in the Fragile Garter Snake), while snakes have no legs.

All reptiles in the region are carnivorous predators. Depending on the species, they hunt insects, amphibians, fish, small mammals and bird eggs.

Most species are oviparous, laying between 5 and 50 eggs that take up to 20 weeks to hatch. The "nests" they choose are fairly warm and partially protected from predators. Piles of manure, stones or wood and rocky crevices are all suitable breeding environments. Some species (Coronelle lisse, Orvet fragile, Lézard vivipare and Vipère aspic) are ovoviviparous. In other words, the females produce eggs that develop inside the body until they hatch. In time, the females give birth to juveniles that are practically autonomous.

Snakes are also unique in that they can find their way around using their jaws and two other means. Firstly, they can detect vibrations in the ground and interpret them to find their bearings. At the same time, the Jacobsen's organ, located in the jaw, transforms tastes into smells. Thanks to the smell of ingested food, and if necessary by "tasting" the ground, snakes can find their way around the environment according to a sort of olfactory map.

In the Lake Geneva region, pressure on reptile habitats continues to be high, particularly through reduced connectivity between favourable sites. The isolation of small populations can lead to fatal genetic impoverishment. In addition to landscape fragmentation, human activities can cause direct damage. Roads and lawnmowers are major hazards for these species. So if reptiles are to survive in the long term, it is essential that connectivity between habitats is strengthened and that they have sufficient hiding places to protect themselves from predators and humans. Ideally, these hiding places should be close to sunny spots such as walls, stone slabs or piles of branches, so that they can store heat. Extensively landscaped gardens with plenty of insects and small animals to feed on are also ideal. Common Garter Snakes also like damp biotopes such as garden ponds or small streams.

♣ Species present in our book of determination sheets (sold in our shop)

Watching reptiles :

Viperine snake (Natrix maura)

Considérée comme le reptile le plus menacé de la région, la Couleuvre vipérine est un serpent pouvant atteindre un mètre. Son corps est vert foncé et est traversé par un dessin brun-noir en zigzag le plus souvent continu. Très proche de la Couleuvre tessellée, elle se différencie de cette dernière par la présence de trois écailles entre l’œil et le nez. ♣

Tessellated snake (Natrix tessellata)

PA close relative of the viperine snake, the tessellated snake occurs naturally south of the Alps. It was introduced by humans that enabled it to colonise a number of sites north of the Alps, where it is gradually gaining the upper hand over the Viperine snake. The north-east bank of Lake Geneva is one of the only places where the two species cohabit. ♣

 


Helvetic snake (Natrix helvetica)

Considered a subspecies of the Common Garter Snake until 2017, the Helvetic Garter Snake can be distinguished from the previous two species by its white collar edged in black. Mainly aquatic, it hunts small amphibians and fish. ♣

Asp viper (Vipera aspis)

Asp vipers are rarely found on the shores of Lake Geneva. On the other hand, they are a regular sight on the first slopes of the north shore. The vertical pupil and triangular head shape allow a viper to be identified with certainty from a snake. ♣

 

 

 

Fragile Orvet (Anguis fragilis)

This is not a snake! From the suborder lézards, l’espèce se distingue par l’absence de pattes. Les adultes sont bruns ou gris et les jeunes ont une coloration dorée ou argentée avec des écailles lisses et brillantes. Vu du dessus, un orvet est uniforme du cou à la naissance de la queue, son corps est cylindrique et sa section parfaitement ronde. A la différence des serpents, les écailles ventrales sont petites et du même type que les autres. L’orvet, comme les autres lézards, possède des paupières, alors que les serpents en sont dépourvus.

 

Green lizard (Lacerta bilineata)

The Green Lizard is the largest and most colourful species in the region. This species needs a varied habitat (woodland, tall grass, rocky outcrops, etc.) and peace and quiet. Its presence is a good indicator of the quality of an ecosystem.

 

Wall lizard (Podarcis muralis)

The most common species around the lake. This small lizard can easily be found on any sunny site with a few hiding places (low walls, riprap, stumps, etc.).

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