Barred Grass SnakeNatrix helveticaWhere and when to see them

The Barred Grass Snake is a non-venomous European snake closely associated with wetlands and freshwater. It occurs across much of western Europe, including river landscapes along the Rhine, Saône and Seine. An accomplished swimmer, it moves readily between water and surrounding terrestrial habitats. Formerly treated as a subspecies of the Grass Snake, Natrix natrix, it was recognised as a separate species in 2017.

Size

Usually 60–100 cm long; large females can reach around 150 cm.

Weight

Varies considerably with size and sex; large females can weigh several hundred grams.

Lifespan

Can live for around 20 years.

Status

Least Concern (IUCN).

Barred Grass Snakes are mainly active during daylight, adjusting their movements to temperature and weather. They bask in sunny, sheltered places to warm themselves before foraging. In water, they swim with sinuous movements and can dive below the surface. When disturbed, they usually retreat into vegetation or water rather than confront a threat. If caught, they may release a foul-smelling secretion, hiss or feign death, sometimes rolling onto their backs with their mouths open. Mating generally takes place in spring, and females lay eggs in warm, humid material such as decomposing vegetation during early summer. They spend the coldest months inactive in frost-protected refuges, sometimes sharing these sites with other snakes.

• Its eggs can be incubated by heat from decomposing vegetation.
• Several females may use the same egg-laying site.
• Playing dead is part of its defensive repertoire.
• Genetic research helped establish it as a separate species in 2017.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Typical habitats include marshes, ponds, lakeshores, riverbanks and wet meadows. Along the Rhine, Saône and Seine, quiet backwaters, floodplain wetlands and vegetated banks can provide suitable conditions. The species also uses woodland edges, hedgerows and gardens, sometimes travelling well away from open water. It needs a combination of prey-rich feeding areas, sheltered basking places, egg-laying sites and safe overwintering refuges.

Amphibians, especially frogs, toads and newts, form the main part of its diet. It also takes tadpoles and fish when opportunities arise. Prey is swallowed whole rather than killed by constriction.

Common name

Barred Grass Snake

Scientific name

Natrix helvetica

Animal group

Reptiles

Size

Usually 60–100 cm long; large females can reach around 150 cm.

Weight

Varies considerably with size and sex; large females can weigh several hundred grams.

Lifespan

Can live for around 20 years.

Status

Least Concern (IUCN).

Identification

The body is usually grey, olive or brown, with conspicuous dark vertical bars along the flanks and smaller dark markings on the back. A pale yellow or whitish collar, bordered by black, is often visible behind the head, although it can become faint or absent in older individuals. The scales are keeled and the pupils are round. Compared with Natrix natrix, the flank bars are generally stronger, but variable markings and hybridisation mean some snakes cannot be identified confidently from a distant view.