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Home , Dice snake, Kvarner Gulf, Natrix, Plitvica (river), Zrmanja

SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE 191

Rediscovery of the Dice N. tessellata inhabiting Croatian Adriatic tessellata (lAuRENTi , 1768), islands (cf. TóTH et al. 2006; SCHWEigER 2008, 2012; J Elić & l ElO 2011). For exam - from the island of , ple, for the island of krk there is only one voucher, a photograph of N. tessellata taken in spite of its natural occurrence and on April 10, 1985, by the herpetologist Mi - locally common presence in Croatia, the chael FRANZEN (cf. SCHWEigER 2008, 2012). Natrix tessellata (lAuRENTi , The latter author suggested that this speci - 1768), is rare or completely absent from men might be a successor from intro - along most of its Adriatic coast ( JElić & duced by a reptilian dealer, who used to lElO 2011). Crucial factors for the snake’s release his surplus of unsold north Balkan presence in the region were thought to be on krk island every fall until the the availability of freshwater and concurrent early 1970s. However, regardless of the re- fish prey, which are particularly abundant cent intensive search by many field herpeto- more inland in the Dinarid karsts (e.g., logists including the authors of this paper, lakes, river, river, no additional specimen of N. tessellata Baćina lakes, vrana lake near ). could be found, and thus, this was Thus, because of the scarcity of freshwater no longer considered part of the natural her - systems, previous published occurrences of petofauna on krk island. Dice Snakes on several Croatian islands or Figure 1 shows the positions of all pub- other areas along the Adriatic coast were lished record localities of N. tessellata on disputed ( JElić & l ElO 2011). Such litera - krk island. These include four sites: Suho ture records for N. tessellata refer to the Ričina, a watercourse near Baška (Fig. 2B; islands of , krk and Prvić ( BRuNO 1980; BRuNO 1980, 1988; SOCHuREk 1985), the SOCHuREk 1985; F RANZEN 1987; M RŠić et Ponikve Dam (Fig. 2C; BRuNO 1980, 1988; al. 1989; SCHiMMENTi & F ABRiS 2000). Mis - SCHiMMENTi & F ABRiS 2000), the Jezero Dam identification and intentional introduction (Fig. 2D; BRuNO 1980) and a small marsh were further confusing the autochthony of near Miholjice south from Njivice in the

Fig. 1: Outline map of the island of krk with all reported locations of findings of Natrix tessellata (lAuRENTi , 1768). Points A-E relate to the habitat pictures in Fig. 2. 192 SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE

northern part of the island (Fig. 2E; FRANZEN nearest mainland (Crikvenica), but the 1987). However, the lack of vouchers, such island’s shortest distance to the mainland is as live or preserved specimens or photo - only 0.5 km at its northern tip. The speci - graphs to verify species identities for three men showed a conspicuous pale dorsal of those localities generated uncertainty ground coloration with dark spots (comp. about the accuracy of such information. e.g., JElić & l ElO 2011). More precise data SCHiMMENTi & F ABRiS (2000) alleged - about morphometrics and pholidosis was ly observed the mating behavior of N. tes - not recorded. After photographic documen - sellata on June 7, 1995, at the Ponikve Dam. tation, the specimen was released back to its They report simultaneous and frequent mat - locality. A subsequent survey of the stream ings of the Natrix natrix area more than one year later on May 22-24 (l iNNAEuS , 1758), at the same site. The and June 4, 2013, yielded no additional Dice Snake observation might represent a specimens. Syntopic species of confusion with the helvetica morph of the and reptiles at the locality were: Pelophylax grass Snake, which superficially resembles ridibundus (P AllAS , 1771) , tadpoles of Bufo N. tessellata in its color pattern of gray dor - bufo (l iNNAEuS , 1758) , Podarcis siculus sum with black ish spots. However, the (RAFiNESquE -S CHMAlTZ , 1810) and Hier - authors were affiliated with institutes (uni - ophis gemonensis (lAuRENTi , 1768) . The versity and public aquarium) that deal with stream was well populated by Mullets most poikilothermic including reptiles probably Mugil cf. cephalus . The new and originated from a region (genova, ) record of N. tessellata on krk confirms pre - that is home to both above and one more vious reports, thereby increaseing the num - species of the Natrix , rendering these ber of snake species of the local herpetofau - observers credible (also confirmed by v. na to a total of 11 (cf. SCHWEigER 2004, FABRiS , pers. comm.). BRuNO ’s (1980) and 2012 ). SOCHuREk ’s (1985) reports of N. tessellata interpretation of an isolated find of a gain credibility, as both authors are well single specimen is difficult and often specu - known experts of reptiles. However, BRuNO lative. As for the lack of information on a (1980) once uttered to intentionally publish reproductive population (and not just a wrong localities to promote others to search handful historical records of Dice Snakes), harder in those areas (cf. SCHWEigER 2012). N. tessellata may not belong to the perma - But in this case, we have no indication that nent fauna of krk. From an eco-biogeo - he has done so with his Dice Snake obser - graphical point of view, it may be interest - vation from krk island, and hence, include ing, that similar to N. tessellata , the Eastern his records on the plausible grounds that (i) Montpellier Snake Malpolon insignitus suitable habitat is available on the island (g EOFFROy DE ST-H ilAiRE , 1809), occurs on (pers. obs.), (ii) a few different records from the mainland and on the neighboring island krk island made by other authors corrobo - of Cres ( BRuNO 1980; T óTH et al. 2006), rate his finding, and (iii) there are records of whereas a viable population on krk was Dice Snakes from other, nearby islands (see never reliably confirmed. Single specimens below). observed on that island were classified On September 28, 2011, at 15:45 h, an introduced ( SOCHuREk 1985; S CHWEigER adult specimen of N. tessellata (Tl approx. 2012). Surprisingly, a recent field expedi - 60 cm, Fig. 3) was found by one of the tion rediscovered three Dice Snakes on the authors (Mk) in the channelized stream veli inland freshwater on Cres Potok (Fig. 2A) in the north-eastern part of island ( BuRić & B AŠkiERA in press), indi - this island. Air temperature was 20 °C. The cating the presence of a natural population stream flows into the gulf of Soline in an there. area known as Meline, situated between the The origin of the individual reported villages of Čižići and Soline (45.14906 N, here from krk remains unclear and the 14.59949 E; 0-1 m a. s. l.). The stream bed question about any permanent, reproductive consists largely of stones, but bank and bed population unanswered. The bright col - become more muddy upstream of the estu - oration of the new specimen is typical to ary. The locality is approx. 7 km from the Dice Snakes from along the northern Dal- SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE 193

Fig. 2: Habitats of Natrix tessellata (lAuRENTi , 1768) at current and historical finding locations on the island of krk. A - Part of the veli potok stream, where the new record of N. tessellata comes from (photographed on May 24, 2012; photo: M. kuDlÁČEk ); B - Suho Ričina (photographed on June 3, 2013); C - Ponikve Dam (photographed on May 25, 2012); D - Jezero Dam (photographed on June 6, 2013); E - Marsh near Miholjice (photographed on May 18, 2007). Photos B−E: P. vlČEk .

matian coast (e.g., JElić & l ElO 2011), and i.e., directly introduced or a successor of thus hints at a regional origin. The newly specimens introduced in the past, or (ii) found specimen is either (i) allochthonous, autochthonous, i.e., a natural immigrant or 194 SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE

Fig. 3: The specimen of Natrix tessellata (lAuRENTi , 1768) from the veli Potok watercourse on the island of krk, found on September 28, 2011. Photo: M. kuDlÁČEk . member of a local indigenous population. malnutrition or lack of proper hibernation Although deliberate release even of allo- sites. This could explain their apparent rari - chthonous reptiles on krk that may include ty on the island. Furthermore, frequent trans- Dice Snakes, cannot be doubted ( SCHWEi- marine dispersal would require a healthy gER 2012), no visibly sustainable population source population on the nearby mainland. of N. tessellata appears to have developed Such are not known, and the coastal stretch since, although successful introductions are on the mainland next to krk island provides known from elsewhere in Europe (e.g., little quality habitat for N. tessellata with no MEBERT 2011 b; O BST & S TRASSER 2011; records to date ( JElić & l ElO 2011). TROBiSCH & gläSSER -T ROBiSCH 2011). However, with a closer look at the vis- The potential for autochthony of N. à-vis coast using satellite and Panoramio tessellata on krk island is likely to exist, as images (googleEarth), the authors perceived this species exhibits remarkable migratory a few small mainland water courses, where abilities, resulting in a dynamic and fast col - still undetected N. tessellata may exist in onization of suitable habitats and subse - low numbers. For example, the town quent rapid population growth (e.g., BENDEl Crikvenica provides potential habitats at the 1997; B AHA El DiN 2011; M EBERT 2011b, stream Dubračina and its upstream widen - 2011c; STRugARiu et al. 2011; vElENSký et ing, lake Tribaljsko. The mouth of the river al. 2011; MEBERT et al. 2013). in contrast, lies only 2.5 km opposite of krk island and the rarity of reported N. tessellata seems to the Soline Bay, into which the stream veli doubt the successful colonization of krk Potok drains (the new record site of the Dice island through transmarine dispersal of indi - Snake). A similar situation, albeit with larger viduals from the near mainland. Alterna- distances to krk island, exists for the urban tively, landing on inferior habitat stretches stream at Novi vinodolski, discharging into on coastal krk may decrease survival of the Adriatic ca. 9 km south of Crikvenica, newly arrived, exhausted snakes; most and the Rječina River at the seaport of would die after one season, either through , 23 km north of Crikvenica. Dice SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE 195

Snakes are well known to have adapted to nent occurrence of this species; the distance conditions of sea coasts and foraging in to the mainland is small and the environ - marine habitats (e.g., gRuSCHWiTZ et al. ment on the island is adequately varied with 1999; vAN DER MEiJDEN & C HiARi 2006; many types of aquatic habitats. it has ap- NAuMOv et al. 2011; STRugARiu et al. 2011; propriate coastal habitats, including rocky TuNiyEv et al. 2011). Regarding the Adriatic shoreline and calm areas for foraging, simi - Sea, coastal/marine Dice Snakes have been lar as can be found in many other coastal documented from the italian coast, from marine populations of Dice Snakes (see ref - Duino to the Delta of the Po River south of erences in MEBERT 2011a). inland, the venezia ( BONATO et al. 2007; MEBERT species could exist in any irrigation channel, 2011c), the Sečovlje saltpans, Adriatic coast like the current find from veli Potok, and of , ( kROFEl et al. 2009; ŽAgAR et stream that provide structures for shelter al. 2011), and in Croatia, from Ston and the and fish to prey on. Open freshwater habitats deltas of the Zrmanja and krka rivers ( JElić like ponds or lakes farther inland (e.g., & l ElO 2011; JElić & l AuŠ 2011). Ponikve Dam, Jezero Dam, and the marsh Due to the remarkable saline tolerance near Miholjice) appear to offer suitable by N. tessellata , Dice Snakes from the Raša habitat requisites for N. tessellata (see Fig. River (records in JElić & l ElO 2011) on the 2). The freshwater systems on krk are southern coast of the Pen insula could densely populated by N. natrix , which does swim/drift 15 to 25 km across the sea to however not preclude sympatry with N. tes - reach Cres island, that in fact holds a sellata. Co-existence between these Natrix population ( BuRić & B AŠkiERA in press), species is a common phenomenon, as niche which is nearest to krk island. Water dis - segregation based on microhabitat and food charging from the mouth of the Raša River is distinct (e.g., JANEv HuTiNEC & M EBERT flows toward Cres island and could easily 2011; iOANNiDiS & M EBERT 2011). Only lead swimming/floating Dice Snakes to limited resources could lead to interspecific Cres island. From there, in the sense of a competition ( METZgER et al. 2009), but this stepping stone, transmarine dispersal of does not apply to krk island. Dice Snakes to krk would require only a Considering the previous reports of N. short, 3 to 5 km distance to swim. Such dis - tessellata on krk island and the new speci - tances may well be crossed by Dice Snakes, men from the veli Potok channel, the avail - as islands and even oil rigs and platforms ability of suitable habitat on the island and its between 5 km to 10 km from the nearest vicinity, and the verified findings from firm land are colonized by this species in the neighboring islands (Cres and Prvić), the Caspian Sea ( TuNiyEv et al. 2011). in the authors suggest to classify N. tessellata as an study region, even larger distances of up to autochthonous faunal element of krk. low 65 km were covered by another semi-aquat - population size and potential of nocturnal ic species, the European Pond Turtle, behavior on a dry, windy island (e.g., Emys orbicularis (l iNNAEuS , 1758), as MEBERT et al. 2011; more references in suggested by JElić et al. (2012). These MEBERT 2011a) may contribute to low de- authors report that 14 of 21 turtles were still tection probability. The authors expect future alive when they were detected on the island searches in the aquatic habitat near the Soline of korčula in De cember 2010, either walk - gulf and across the island to reveal a popula - ing around or still entangled in floating tion of N. tessellata on krk island. sedge. They probably arrived there by hav - ACkNOWlEDgMENTS: The authors thank ing floated on driftwood from the M. SCHWEigER () B. HORvATiČ and D. J Elić estuary across seawater, around Janjina (both Croatia) for helpful information to biology and Peninsula to the shores of korčula island distribution of N. tessellata in this region and B. lOJkÁSEk and R. ŠANDA (both ) for the (JElić et al. 2012). determination of the fishes from the veli Potok. The question arises if there is suitable habitat for N. tessellata on krk island. REFERENCES: BENDEl , P. (1997): Zur Physio - logie, Morphometrie und Populationsökologie der Wür - According to the authors’ experience, this felnatter Natrix tessellata am Alpnachersee. Master’s island is, among all kvarner islands, the thesis, Zoological Museum, university of Zurich, most suitable for colonization and perma - , pp. 57. BAHA El DiN , S. (2011): On the 196 SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE

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(2011a): The Dice Snake, Natrix tes - Prague.- Mertensiella, Rheinbach; 18: 157-177. ŽAgAR , sellata : biology, distribution and conservation of a A. & k ROFEl , M. & g OvEDiČ , M. & M EBERT , k. (2011): Palaearctic species.- Mertensiella, Rheinbach; 18: 1- Distribution and habitat use of dice snakes, Natrix tes - 468. MEBERT , k. (2011b): introduced and indigenous sellata , in Slovenia.- Mertensiella, Rheinbach; 18: 207- populations of the dice snake ( Natrix tessellata) in the 216. central alps – microgeographic yariation and effect of inbreeding.- Mertensiella, Rheinbach; 18: 71-80. kEy WORDS: New record, Natrix tessellata , MEBERT , k. ( 2011c): Terrestrial dice snakes: how far (), zoogeography, krk island, from water a semiaquatic snake ventures out?- Merten - , Balkan Peninsula siella, Rheinbach; 18: 436-438. MEBERT , k. & T RAPP , SuBMiTTED: September 12, 2013 B. & k REiNER , g. & B illiNg , H. & S PEyBROECk , J. & HENggElER , M. (2011): Nocturnal activity of Natrix AuTHORS: Petr vlČEk - Slovanská 5, 736 01 tessellata , a neglected aspect of its behavioral Havířov-Město, Czech Republic < [email protected] >; repetoire.- Mertensiella, Rheinbach; 18: 234-237. Daniel JABlONSki - Department of Zoology, Comenius MEBERT , k. & M ASROOR , R. & C HAuDHARy , J. i. (2013): university in Bratislava, Mlynská dolina B-1, 842 15, The dice snake Natrix tessellata (Serpentes: Colu - Bratislava, < [email protected] >; bridae) in : analysis of its range limited to few Marcel kuDlÁČEk - Střelecký vrch 690, 463 31 valleys in the Western karakoram.- Pakistan Journal of Chrastava, Czech Republic < [email protected] >; Zoology, lahore; 45 (2): 395-410. METZgER , C. & konrad MEBERT (Corresponding author < konradmebert uRSENBACHER , S. & C HRiSTE , P . (2009): Testing the @gmail.com >) - Department of Environmental Sci - competitive exclusion principle using various niche ences, Section of Conservation Biology, university of parameters in a native ( ) and an introduced Basel, St. Johanns-vorstadt 10, 4056 Basel, Switzer - (N. tessellata ) colubrid.- Amphibia-Reptilia, leiden; land. The authors declare that they all contributed 30: 523-531. MRŠić , N. & N EMESCHkAl , H. l. & equally to this work.