The Natrix natrix complex has long been treated as a single widespread species throughout Europe and temperate Asia. Numerous subspecies have traditionally been recognised; recent molecular evidence indicates that most of these are not supported genetically (Speybroeck et al. 2016), including the formerly recognised species Natrix megalocephala, but that the grass snake forms three geographically discrete clusters, each of which has recently been recognised as distinct species: Natrix astreptophora (Iberia) (Porkrant et al. 2016), N. helvetica (northern and central Europe) (Kindler et al. 2017) and N. natrix. The taxonomy of grass snakes still included within N. natrix east of the range of N. helvetica, remains unresolved. Fritz and Schmidtler (2021) recognise several mtDNA lineages within Natrix natrix that may represent cryptic species, including an Iranian lineage originally described as Coluber persa a widespread lineage from Poland to Kazakhstan to which they apply the name Natrix natrix scutata, but refrained from making taxonomic changes in the absence of additional genetic data.

Fritz and Schmidtler (2021) investigated the complicated history of available names for proposed subspecies of all three recognised grass snakes, with the goal of laying groundwork for a revision of subspecific boundaries within these taxa. These authors referred a number of names to synonymy and recommended that Natrix gronoviana, Coluber arabicus, C. torquatus, C. irroratus, Natrix hybridus, Tropidonotus oppellii. Tropidonotus fallax and Coluber niger - all names associated with the grass snakes by various authors - be treated as nomina dubia, along with several names for "varieties". They provisionally recognised the valid subspecies Natrix natrix vulgaris, N. n. scutata, N. n. persa (whose range limits are unclear), and N. n. syriaca as well as the nominate subspecies. They report that genetic evidence does not support the recognition of the subspecies N. n. cypriaca, but citing a need for further work do not include it in either their list of proposed subspecies or in their list of synonyms.

European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

This species is widespread across the European region. It is assessed as Least Concern for both Europe and for the EU27 Member States in view of its wide distribution, tolerance of a degree of habitat modification, presumed large population, and because the overall population trend is thought to be stable across its vast range both in Europe and the EU 27.

This species ranges widely through the European region, with a western range limit in Germany and Switzerland where it occurs sympatrically with Natrix helvetica, and has an eastern European range limit in European Russia (Kindler et al. 2017). It is absent from northern Scandinavia and Crete (Greece). It occurs on Cyprus, where species distribution models conducted in 2022 revealed a geographic range larger and wider that was previously thought in both the Troodos Mountains and Paralimni (Zotos et al. 2022). It is known from isolated, individual records in the Crimean Peninsula (Ukraine).

From Europe, it ranges through Asian parts of Russia eastwards into Kazakhstan (where it occurs through the northern half of the country south approximately to the northern boundary with the Caspian Sea. 19th Century records from the east coast of the Caspian have never subsequently been confirmed - T. Dujsebayeva pers. comm. 2017), Turkmenistan (the valley of the Atrek River, and the channel linking Maloe Delili with the Caspian Sea; Ananjeva et al. 2006), China and northern Mongolia. It occurs in most of Türkiye, the Caucasus, and in northwestern Syria (only known from a couple of localities where it is very rare). In Iran, it has been recorded from Mazandaran Province, Ghilan Province, East Azerbaijan Province and Central province (Latifi 1991). Globally, it ranges from sea level up to 3,060 m asl.

This is a common species but with fragmented subpopulations through parts of its range, especially in southern areas. In some regions it is very common (e.g., up to 120 specimens recorded per hectare in the Donetsky Range, Ukraine).

The endemic subspecies from Cyprus is very localised. Although more widespread than presently recognised, it remains known mainly from the Troodos Mountains and a single lowland area (Zotos et al. 2022). It was described as being very common in the early 20th Century, but it was so rare by the early 1960s that it was believed to be extinct until its rediscovery in 1992 (Wiedl and Böhme 1992). Although it was believed to have been lost from one locality, Xyliatos, where approximately 450-650 individuals were believed to survive by the mid-1990s and as of 2008, the total number of remaining animals was estimated as 69-148 (Baier et al. 2013). Individuals were reported from this locality by citizen science and confirmed by the Department of Forest early in 2022. Although it has been reported in low numbers from 13 new localities, a "healthy population" appears to exist only within the Dasos Machaira protected area (Zotos et al. 2021). This species is however elusive and dark morphs can be confused with the Large Whip Snake, a more common species, and evaluating the true population status of the Cypriot subspecies will require systematic monitoring (Zotos et al. 2022).

This snake is typically found in damp places, such as wet meadows, around standing water and along the banks of streams. It is sometimes found a long way from any standing water and can often be found in wooded localities and in heathland. It is tolerant of heavily-modified lansdcapes where suitable water sources are present, and can live in domestic gardens and urban parkland. In Cyprus, sparsely-distributed springs within ephemeral stream systems appear to be important for the Troodos Mountains subpopulation, while lowland records are associated with small natural wetlands or artificial irrigation pools (Zotos et al. 2022).

This species swims well and typically forages on fish and amphibians. It also eats young birds and small mammals. Larger females may lay up to 100 eggs (but usually fewer) during June and July (Speybroeck et al. 2016). Young females of Natrix helvetica lay about 10 eggs, which is presumably also the case for this species (Spellerberg 2002).

It is locally threatened in parts of its range by water pollution impacting prey populations (principally amphibians), drainage of wetland habitats (in Switzerland 90% of wetland habitats have been drained; A. Meyer pers. comm.) and general intensification of agricultural methods.

Records from the late 19th Century suggest the species - represented by the endemic subspecies Natrix natrix cypriaca - may once have occurred island-wide on Cyprus. Its present distribution was believed to be highly restricted to several localities in the northern and central Troodos Mountains and a locality near Paralimni (Baier et al. 2013). Recent studies, conducted in 2021, revealed the first new records in 25 years (Zotos et al. 2021), while a species distribution model suggested a potential geographic range larger and wider than was previously thought (Zotos et al. 2022) and led to the discovery of additional sites (Zotos et al. in review). An apparently rapid decline between the early 20th Century and the 1960s may be attributable to one or several factors including DDT, agricultural and building development, wetland drainage, and diversion of water flows (Baier et al. 2013). The subsequent drastic decline of the Xyliatos subpopulation might be linked to the introduction of several invasive fish, which compete with the snake for amphibian prey, impact its suitability for frog populations, and may attract populations of predators that also consume grass snakes (Baier et al. 2013). Elsewhere in the snake's range, mortality of animals has been reported from damage to the body wall following predation attempts on invasive fish (Šukalo et al. 2012). The one remaining subpopulation outside the Troodos Mountains was considered to be in "extreme danger" from lakeside development, ongoing agriculture, and associated habitat destruction, while the Troodos subpopulations are at risk from hydrological changes due to dam-building and irrigation (Baier et al. 2013).

Some subspecies are considered to be threatened. On Milos, the species is threatened also by mining activities (A. Westerström pers. comm.). As with many snakes this species is generally persecuted by people. Roadkill is a threat in many areas, and habitat fragmentation through development.

In Germany wetland clearance over the past century is considered to have led to significant declines in the two grass snake species in this country, although subpopulations may now be stable or increasing in areas where this pressure has slowed or wetland restoration has taken place (Rote-Liste-Gremium Amphibien und Reptilien 2020).

There appears to be no substantial use of this species. Terbish et al. (2006) report that there may be low levels of exploitation for the international pet trade in China and Russia, but provide no details.

This species is listed on Annex III of the Bern Convention. It is protected by national legislation in some range countries. It is present in many protected areas throughout its range. The construction of corridors underneath roads could aid in significantly reducing mortality on roads for some populations (J.M. Pleguezuelos pers. comm. 2008). N. n. natrix is categorised as Endangered in Switzerland in the last Red List (Monney and Meyer 2005, OFEV and info fauna 2023). N. natrix cypriaca is considered Critically Endangered (Blosat 2005) but has been subject to very few effective conservation measures, with most management targeted at the near-extirpated Xyliatos dam subpopulation (Baier et al. 2013). A captive breeding program for this subspecies failed due to a lack of specimens (Baier et al. 2013). The remnant subpopulations are now protected in Natura 2000 sites and a species recovery plan is in place, but more effective protection and management of these areas is required (the latter including the complete removal of invasive fish and crayfish from these sites) (Baier et al. 2013). These authors recommend a complete distribution survey, annual monitoring and the establishment of a long-term captive breeding program; as of Zotos et al. (2021) none of these measures had been implemented. These latter authors propose installing small waterbodies with gabions that can manage water flow without damaging surrounding terrestrial habitat, as well as the expansion of Natura 2000 sites to encompass the new localities reported for the subspecies.

The success of the citizen science efforts reported by Zotos et al. (2022) highlight the importance of conducting further research to clarify the species' distribution and population system, and these authors recommend developing a systematic monitoring programme. These new findings have permitted the creation of species distribution models examining the species' potential future distribution in the Troodos Mountains under two climate change scenarios, resulting in a predicted reduction of species' distribution in the Eastern Troodos Mountains by up to 50% (Stamatiou 2022). Least Cost Path Analysis (LCPA) was conducted to identify connectivity corridors in need of management and conservation for the species (Stamatiou 2022).