Dice snake (Natrix tessellata)

16 May 2016
Natrix-tessellata-Foto

It is a widely encountered species both in Europe and in Romania, reported from the sea level to the altitude of 1000 meters a.s.l. [3, 4, 5]

The Geographic Range of  Natrix tessellata in Europe [5]

The Geographic Range of Natrix tessellata in Europe [5]

Although a species with a large distribution complex, in Romania the areas where it can be encountered are quite scarce. [10]

The Geographic Range of Natrix tessellata in Romania [1]

The Geographic Range of Natrix tessellata in Romania [1]

Morphology. It is an average sized, slender snake, over 1m long. The head is long and narrow, with 8 upper labials (sometimes 7 or 9), 2-3 preoculars and 3-5 overlapping postoculars. The dorsal scales are strongly streamlined and disposed in 19 transversal rows, midlength counted. The number of the ventral shields varied between 160 and 187, the anal plate is divided and the subcaudals count between 48 and 97. Males are differentiated from females by a change in aspect at the base of the tail, serving to the immobilization of females during coupling. [3, 4]

The colour of the dice snake’s back varies from yellow to green and grey. On this background, five rows of square spots can be distinguishes – or not – and often a ”Ʌ”- shaped spot on the back of the head. The ventral side is yellowish white or brick red with alternated black spots. The juveniles have the same colours as the adults. [3, 4]

Ecology. It is a daytime species, preferring the water habitats, staying in the water for longer periods of time than Natrix natrix. [7, 8] It can be encountered in the water or in its close proximity, rarely at considerable distances from a water body. It feeds on small fish, frogs, newts and tadpoles, actively hunting in the water. [3, 4, 2, 9] When observed, its first reaction is to run away, to hide in holes, cracks or, if close by, it will seek refuge in the water. If it cannot hide, it will adopt an aggressive behavior, intimidating the naive observer, by curling, hissing loudly and striking with the head, but without biting. If it is handled or picked up, it will spread the badly smelling content of its anal glands. If the stress continues, the snake will play dead, curled up on its back. Its natural enemies comprise water fowl, birds of prey, hedgehogs, etc. It hibernates from October to April. [3, 4]

Reproduction takes place in June and July. Females burry their eggs in the soil, at shallow depths, one nest holding from 5 and 25 of long, white eggs sticking to one another. Incubation lasts for approximately 10 weeks and the juveniles have between 16-19 cm when hatchlings. [3, 4]

Legislation. In Romania, the species is protected by Law no. 13 of 1993, by which Romania ratifies the Bern Convention (Annex II), as well as by the European Directive 92/43/EEC (Annex IV) and by the Emergency Government Order no. 57/2007 on the regime of natural protected areas, conservation of natural habitats, of wild flora and fauna, approved with further modifications and completions (Annex IVA), being considered a species of community interest requiring strict protection [11, 12, 13].

According to the IUCN classification, worldwide the species’ status is of least concern (LC), while in Romania’s Vertebrate Red Book, the species is classified as nearly threatened (NT) [6, 14].

References

1. Cogălniceanu D., Rozylowicz L., Székely P., Samoilă C., Stănescu F., Tudor M., Székely D., Iosif R., (2013): Diversity and distribution of reptiles in Romania, ZooKeys 341: 49-76.

2. Filippi, E., Capula, M., Luiselli, L. & U. Agrimi (1996): The prey spectrum of Natrix natrix (Linnaeus, 1758) and Natrixtessellata (Laurenti, 1768) in sympatric populations. – Herpetozoa8(3/4): 155–164.

3. Fuhn I.E., Vancea Ș., (1961): Fauna R.P.R. Reptilia (Țestoase, Șopârle, Șerpi). Vol XIV, fasc. 2, Editura Academiei R.P.R., București. [in Ro]

4. Fuhn I.E., (1969): Broaște, șerpi, șopârle. Ed. Științifică, București. [in Ro]

5. Gasc J.P., Cabela A., Crnobrnja-Isailovic, Domen D., Groessenbacher K., Haffner P., Lescure J., Martens H., Marinez Rica J.P., Maurin H., Oliveira M.E., Sofianidou T.S., Veith M., Zuiderwijk A., (1997): Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica & Museum National d’Histoire Naturelle Paris.

6. Iftimie A., (2005): Reptilia. In: Botnariuc & Tatole (eds): Cartea Roșie a Vertebratelor din România. Ed. Academiei Române, București. [in Ro]

7. Ioannidis Y., Mebert M., (2011): Habitat preferences of Natrix tessellata at Strofylia, northwestern Peloponnese, and comparisonto syntopic N. natrix. – Mertensiella 18: 302–310.

8. Janev Hutinec B., Mebert K., (2011). Ecological partitioning among dice snakes (Natrix tessellata) and grass snakes (Natrixnatrix) in southern Croatia. – Mertensiella 18: 225–233.

9. Luiselli L., (2006): Broad geographic, taxonomic and ecological patterns of interpopulation variation in the dietary habits of snakes. – Web Ecology 6: 2–16.

10. Strugariu A., Gherghel I., Ghira I., Covaciu-Marcov S.D., Mebert K., (2011): Distribution, habitat preferences and conservation of the dice snake (Natrix tessellata) in Romania. Mertensiella 18: 272-287.

11. ***Legea 13 din 1993 prin care România ratifică Convenția de la Berna. [in Ro]

12. ***Directiva Europeană 92/43/EEC. [in Ro]

13. ***Ordonanța de Urgență a Guvernului nr. 57/2007 privind regimul ariilor naturale protejate, conservarea habitatelor naturale, a florei și faunei sălbatice, aprobată cu modificări și completări ulterioare. [in Ro]

14. *** www.iucnredlist.org

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