Natrix Tessellata

The dice snake, Natrix tessellata, in Jordan still occurs in viable populations, particularly in northwestern
areas of the country. But numerous populations have become extinct, following habitat degradation due to irrigation
and water pollution. Summary notes on morphology and ecology of Jordanian dice snakes is presented, including
aspects of habitat and coexisting herpetofauna, mating, diet, defense behavior, predation and parasites. Literature
comparisons indicate that the biology of the dice snake in Jordan fits the common profile of this species.

A summary of general aspects of dice snakes from the Caucasian Isthmus, including areas west to the Sea of Azov and east to the Caspian Sea, is presented. The aspects include notes on color pattern, distribution, habitat and sympatric herpetofauna. We conclude this report with relevant accounts on the daily activity and conservation of dices snakes in the Caucasus biogeographic region.

The diet and helminth fauna of 32 dice snakes from the Volga Basin, the Republic Kalmykia and the provinces of Samara, Saratov, Volgograd and Astrakhan were investigated. A total of 33 fish items were retrieved belonging to at least 11 species (Alburnus alburnus, Esox lucius, Lota lota, Misgurnus fossilis, Perca fluviatilis, Rutilus rutilus, Perccottus glenii, Cottus gobio, Carassius carassius, Cyprinus carpio, Neogobius melanostomus, and some unidentified species).
In addition we found 5 tadpoles (Pelophylax ridibundus, and from unidentified ranids); 1 snake (Vipera berus) and one individual of gastropoda (Lymnaea stagnatilis). In Samara, Saratov, Volgograd and Astrakhan provinces 142 snakes have been investigated by complete helminthological dissection. A total of 20 species of parasites were found: 10 species of trematodes (Leptophallus nigrovenosus, Encyclometra colubrimurorum, Astiotrema monticelli, Macrodera longicollis, Telorchis assula, Paralepoderma cloacicola, larval stages of Strigea sphaerula, S. strigis, Alaria alata and Pharyngostomum cordatum), 1 species of cestode (Ophiotaenia europaea), 8 species of nematodes (Rhabdias fuscovenosus, Strongyloides mirzai, Camallanus truncatus, C. lacustris, larval stages of Streptocara crassicauda, Spiroxys contortus, Contracaecum sp., 1 unidentified nematode), and 1 species of acanthocephalan (Сentrorhynchus aluconis, larvae). Comments are made on the ecological correlation between composition of the helminth fauna and the semiaquatic lifestyle and diet of the dice snakes.

Natrix tessellata is relatively common and widely distributed in Georgia. It inhabits most aquatic habitats available in the country. The vertical distribution spans from 0–600 m in the west and 900 m in the east, with few observations up to 1100 m a.s.l, but a negative correlation between precipitation and occurrence at higher altitudes has been documented. Compared to the grass snake (Natrix natrix), the dice snake has a lower abundance in climatically wet areas, whereas N. tessellata occurs more frequently in semi-arid regions. Zusammenfassung. In Georgien ist Natrix tessellata häufig und weit verbreitet. Sie besiedelt hier die meisten aqua-tischen Habitatstypen des Landes. Die vertikale Verbreitung liegt zwischen 0 und 600 m im Westen und 900 m im Osten, mit wenigen Beobachtungen bis zu 1100 m über Meer. Eine negative Korrelation zwischen Niederschlag und Vorkommen in grösserer Höhe wurde dokumentiert. Im Vergleich zur Ringelnatter (Natrix natrix), besiedelt die Würfelnatter die humiden Landesteile in geringerer Häufigkeit, während sich dieses Verhältnis in semi-ariden Ge-bieten kehrt.

Microclimatic characteristics of habitats and thermobiology of the dice snake, Natrix tessellata, were investigated along its northern range limit in the “Samarskaya Luka” National Park, Samara Oblast in Russia. All 123 snakes examined from 2001–2008 were melanistic. Snakes were active at surface air temperatures ≥ 14.0 °C and substrate
temperature ≥ 13.2 °C. Females selected more open areas than males. Females’ body temperatures (measured in the esophagus) were just slightly higher than those of males, whereas males exhibited a higher surface (skin) temperature at the ventral and dorsal area of the tail. At an internal body temperature of 28 °C, a dice snake prevents further
rising of temperature by moving to a cooler site (behavioral thermoregulation). An experiment was conducted to measure the speed of temperature decrease and increase of snakes switching between a sunlit spot (> 30 °C) and a cool water bath. The body temperature decrease was 2.2 °C/min and the increase followed by 0.3–0.4 °C/min untill a
preferred body temperature of about 28 °C was reached.

Food composition of the Dice snake, Natrix tessellata, was studied in the Anatolian part of Turkey. A total of 76 prey items were recorded from 51 museum specimens and compared between sexes and age groups. The diet of N. tessellata consists almost entirely of fishes (72.4%). The remaining stomach contents were insects (7.9%), gastropods (2.6%), amphibians (14.5%), reptiles (1.3%), and mammals (1.3%). Our results confirm that Turkish N. tessellata forage predominantly in water. Food composition did not differ significantly between sexes and age groups, but the largerst prey items were consumed by relatively large females.

The dice snake (Natrix tessellata) is a protected species in Slovenia, whose distribution is incompletely known and only little information about its habitat use is available. We analyzed historical and recent distributional
data and performed a study of habitat use to acquire relevant information for the conservation of dice snakes in Slovenia. Using a line transect method, we compared habitats at localities of recorded dice snakes with habitats available next to the line transects in four buffer zones (10, 20, 50, and 100 m distant from the transect). All transect lines were located in areas of less than 1 km from the rivers Sava and Kolpa. In order to get a better idea on habitat selection, habitat use including all precise localities (n = 117) of dice snakes in Slovenia was analyzed. Dice snakes were recorded mainly in the lowlands throughout the country, but were rare in the northeastern part. Its presence in the river Kolpa was confirmed for the first time. More than 75% of observations were recorded within 10 meters from a water body. To a minor degree, snakes selected grasslands and urban areas along the Sava River and land covered with shrub vegetation at the Kolpa River. Forest habitats as well as agricultural land with herbaceous plants were avoided along the Sava River.

The habitat preferences of Natrix tessellata and N. natrix were studied in the wetlands of Strofylia in southern Greece. Both species used most available water habitats, but N. tessellata dominated in permanent lagoons with brackish water or saltwater. N. natrix uses equally temporary and permanent water bodies and prefered areas with large breeding concentrations of frogs and toads, such as ponds, wet meadows, marshes and a shallow lakes. Based on their surface frequency the habitat overlap between the two species is low. N. tessellata was found to be more aquatic, whereas N. natrix has been observed at large distances from water. Regarding the terrestrial habitats, N. natrix inhabited areas with mainly forests, whereas N. tessellata was common in more open situations, particularly rocky shores with scattered bushes. The hibernation period for N. tessellata is relatively short and lasted around three months.
Some individuals left their hibernaculaum during warm winter days. The terrestrial activity pattern of N. tessellata is unimodal in spring with equal numbers observed throughout the day until dusk. In summer and autumn they switched to a bi-modal activity pattern with many animals active in the morning hours, followed by a sharp decrease during mid-day and a second higher peak around dusk and during the first hours of the night. High road mortality
of N. tessellata was recorded along a stretch of 2.1 km on the north shore of Prokopos Lagoon We estimated that vehicles kill approximately 1100 dice snakes annually on this road.

At present, only 10 localities with fossil remains of Natrix tessellata of Pliocene-Holocene age are known from the East European plain. They are exclusively represented by trunk vertebrae. Due the application of a single diagnostic character, the CL/NAW ratio (centrum length/width of interzygapophyseal constriction), the majority of East European Natrix fossils were determined as Natrix cf. natrix, and a smaller number as Natrix cf. tessellata. The oldest fossil records of N. natrix and N. tessellata originate from the Middle Pliocene. The data conclude that N. tes-sellata inhabited the East European plains continuously since the Late Pliocene until present, but that its range varied due to the frequent climatic and topographic changes.