Natrix natrix

Natrix natrix - Ringed snake (grass snake): Linnaeus, 1758

One of the most common species of snakes is Natrix natrix, also called grass snake, ringed snake or water snake, a non-venomous snake with a wide distribution.

Description:
Natrix natrix is a moderately slender snake with a distinct head, short, obtuse, not prominent snout, lateral nostrils, moderately large eyes with round pupil. The rostral is broader than deep and visible from above; nasal divided, internasals larger than half of the prefrontals. The frontal is broader than the supraocular, shorter than the parietals and not in contact with the preocular. The loreal is deeper than long. It has one (rarely two) preoculars, three (rarely two or four) postoculars and seven upper labials (rarely six or eight), third and fourth (or fourth and fifth) entering the eye. Its scales are keeled, with two apical pits, in nineteen rows, of outer row smooth or faintly keeled. Ventral shields 157 to 181; anal divided; subcaudals 50 to 88.
The coloration of Natrix natrix is very variable. Typically is grey, bluish-grey, olive or brown above, usually with smaller black markings or narrow bars along the back, and a variable row of black bars along the sides. The upper lip is whitish or yellowish, with the sutures between the shields black; a white, yellow, or orange collar on the nape, divided in the middle, sometimes uninterrupted, bordered behind by two black blotches, which usually meet on the median line; belly usually checkered black and grey or white, more rarely grey with black spots, or entirely black. The iris is dark brown or reddish brown, with a golden circle round the pupil.
Other color variations: Britain, France, Switzerland, central Italy: the collar is pale or absent, flanks usually have dark bars, back may have small spots in two alternate rows. Collar orange, white or pinkish, usually divided in the middle, with black triangles/crescents on posterior border; Northern and north-eastern Europe: collar well-developed yellow or orange; body often has dark spots; South-eastern Europe, northern Italy: the collar is well developed, body often with two pale stripes along length of body and often has spots; flanks often have bars; Iberian peninsula: generally uniform, collar often absent; Southern Italy, Sicily: the sides and back often have bars; Cyclades: may be almost entirely black, some are flecked with light yellow; collar may not be obvious; body commonly bears three rows of dark blotches; Corsica, Sardinia: collar usually weak; body often has dark bars on either side. A specimen from Algeria, has the posterior half of the head, from between the eyes and behind the postocular shields, of an intense black, followed by the usual yellow and black collar; two light dots close together on the parietal shields. Some specimens are entirely or nearly entirely black. In a subspecies from the Caucasus, the upper parts are sprinkled all over with light dots, and the yellow collar is present; the belly is grey, dotted with black, and with white spots on the sides. In others the body is black above, and checkered black and white beneath, or entirely black. Albinos have occasionally been met with yellowish flesh-color with reddish markings, and a white or yellow collar, the eye and the tongue red.

Biology:
The ringed snake grows up to 190 cm total length, though such large specimens are rare. Females are considerably larger than males, typically reaching a size of 90-130 cm when fully grown. Males are shorter (70-100 cm) and significantly smaller in girth.
During winter, when temperatures are too low, the grass snakes find frost-free places such as deep leaf litter, rock piles, at the root of trees, often under manure heaps in which to hibernate between October and March or April. The awakening occurs in March or April, soon to be followed by the first exuviation and the pairing which takes place in April or in May, according to the climate, the eggs being laid between June and July. Eggs are often laid in warm places e.g. manure heaps, also in wall cavities, old tree trunks, earth of ploughed fields. Female burrows into heap and form a chamber for the eggs (as few as 8-10 from young females, 30-40 usual for fully-grown females and as many as 53 recorded). The eggs are matt white, 25-30mm x 16-20mm when laid; increase in size by several mm within a couple of weeks. It is not very unusual for several females to use same site. The young(15 to 19 cm in length) hatch usually about two months (6-10 weeks) after laying; variation dependant on temperature and possibly on degree of development of embryos at time of egg laying. The hatchling snakes escape from the eggs by chipping at the shell with an egg tooth, which is lost shortly after hatching. Males become mature at 3 years of age, but females do not begin to breed until they reach their fourth or fifth year.
Their food consists on frogs, newts, fish, tadpoles, toads, lizards, young birds, mice, voles and even shrews. Juveniles may take worms, slugs and tadpoles.
This species searches actively for prey, often on the edges of water, using sight and sense of smell consuming prey live without using constriction.
A grass snake's speed and wariness makes it incredibly difficult to spot, but once cornered, feigning death is one of the defensive tactics used by the Grass Snake, others being hissing loudly and exuding a foul smelling liquid from the anal vent if captured.
They may also perform an aggressive display in defence, hissing and striking without actually opening the mouth. They rarely bite in defence.
Grass snakes can live for up to 15 years (20 years in captivity).
This species is mainly diurnal, usually being found in sunlit areas (e.g. sunny side of a valley); may bask on top of shrubs; good climber, may be found in bushes and low trees although does not climb high up.

Habitat:
Like other members of the genus Natrix, the grass snake is an semi-aquatic species that is usually closely associated with water. They are found in habitats featuring ponds, lakes, streams, marshes and ditches, which provide access to sunshine for basking and plenty of shelter. They may be found in open woodland, rough grassland, wet heathlands, gardens, parks and hedgerows and sometimes in dry areas e.g. sandy heaths, chalky downs.

Distribution:
Natrix natrix occurs all over Europe (with the exception of Ireland), as far north as the extreme south-east of Scotland, and the sixty-fifth degree in Scandinavia and Finland, and as high up as 2400 m altitude. With few exception it is common everywhere, in the north as well as in the south. On the Mediterranean islands it is absent from the Baleares and Malta. In North Africa it is known from Algeria and Tunisia, north of the Atlas. It has a wide range in Asia, extending eastwards to Lake Baikal, and southwards to Cyprus, Asia Minor, and Northern Iran.
Countries: Norway, Sweden, Finland, England, France (Corsica), Belgium, Netherlands, Luxemburg, Germany, Poland, Czech Republic (formerly Czechoslovakia), Denmark, Austria, Switzerland, Italy (Sardinia), Hungary, Romania, Yugoslavia: Croatia (including some Adriatic islands), Slovenia, Bosnia and Herzegovina, Monte Negro, Macedonia, Serbia, Albania, Bulgaria, Greece (Limnos, Lesbos, Paros, Antiparos, Despotiko, Chios, Samos, Samothraki, Andros, Corfu), Turkey, Cyprus, Spain, Portugal, Gibraltar, N Iran, Syria, NW China (Xinjiang), Morocco, Algeria, Tunisia Russia, Estonia, Latvia, Lithuania, Belarus, Moldova, Ukraine, Armenia, Georgia, Azerbaijan, Kazakhstan, Turkmenistan, NW Mongolia;.

Scientific name: Natrix natrix

Common name: ringed snake, grass snake

Taxonomy:
Species: Natrix natrix
Experts currently disagree as to the number of subspecies of the grass snake.
Subspecies:
Natrix natrix algirus (fide SOCHUREK 1979)
Natrix natrix astreptophora (SEOANE 1884)
Natrix natrix cetti GENÉ 1838
Natrix natrix corsa (HECHT 1930)
Natrix natrix cypriaca (HECHT 1930)
Natrix natrix fusca CATTANEO 1990
Natrix natrix gotlandica NILSON & ANDRÉN 1981
Natrix natrix helvetica (LACÉPÈDE 1789)
Natrix natrix lanzai KRAMER 1970
Natrix natrix natrix (LINNAEUS 1758)
Natrix natrix persa (PALLAS 1814)
Natrix natrix schweizeri L. MÜLLER 1932
Natrix natrix scutata (PALLAS 1771)
Natrix natrix sicula (CUVIER 1829)

IUCN Status: LC (Least Concern) T
his species is listed as Least Concern in view of its wide distribution, presumed large population and broad range of habitats.

References:
Arnold, E. N., and J. A. Burton. 1978: A Field Guide to the Reptiles and Amphibians of Britain and Europe. Collins, London;
Boulenger, G.A., 1913: The Snakes of Europe;
Covaciu-Marcov S.-D.; Ghira, I.; Cicort-Lucaciu A.-St., Sas I.; Strugariu, A. & Bogdan H. V. 2006. Contributions to knowledge regarding the geographical distribution of the herpetofauna of Dobrudja, Romania. North-Western Journal of Zoology 2 (2): 88-125;
Covaciu-Marcov, S.D., Cicort-Lucaciu, A.S., Dobre, F., Feren?i, S., Birceanu, M., Mihu?, R. & Str 2009. The herpetofauna of the Jiului Gorge National Park, Romania. North-Western Journal of Zoology 5 (Suppl. 1): 1-78;
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Göçmen, Bayram; Mehmet K. Atatür; Abidin Budak; Hasan Bahar; Mehmet Zülfü Yildiz; Nur?en Alpagut 2009. Taxonomic notes on the snakes of Northern Cyprus, with observations on their morphologies and ecologies. Animal Biology 59: 1-30;
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Joger, U. & N. Stümpel, 2005: Handbuch der Reptilien und Amphibien Europas, Wiebelsheim;
Martens, H. 1996. The rediscovery of the Grass Snake Natrix natrix (L.) in the Levant. Zoology in the Middle East 12: 59;
Sos, T. 2008. Review of recent taxonomic and nomenclatural changes in European Amphibia and Reptilia related to Romanian herpetofauna. Herpetologica Romanica 2;
Szczerbak, N.N. 2003. Guide to the Reptiles of the Eastern Palearctic. Krieger, Malabar, FL.