Common Snake Research Articles

Update on the herpetofauna of Syros (Cyclades, Greece) and current land-use and climate change threats

The current knowledge on the herpetofauna of Syros is updated, whereby no publications on it have been made since 1975. I provide the results from a field trip in 2024 that focused on the hygrophilous species. The Balkan Water Frog and the Balkan Terrapin, mentioned for Syros in the 19th century, meanwhile have become extinct. The Green Toad is threatened with extinction, the status of the Grass Snake is unclear. The Green Toad has benefited previously from anthropogenic spawning grounds in the form of open cisterns, which have fallen into disuse and thus are no longer available to the amphibians. The ongoing climate change in the Aegean region is reflected in drier winters, which dry out water bodies. The situation for the wetlands and their fauna and flora on Syros is alarming.

Crabs as snake predators? An observation from southern Italy leading to a comprehensive review

The recent elevation of the Western Grass Snake, Natrix helvetica, from subspecies status prompted an assessment of its natural history and ecological traits compared to closely related species. We report an unusual predation attempt by the freshwater crab Potamon fluviatile on N. helvetica sicula from Sicily, indicating an ecological interaction previously overlooked in this species. The observation suggests that this crab may utilise snakes’ muscle tissue as an additional nutrient source. This predator-prey interaction, although probably rare, adds to the understanding of the dynamics between crabs and snakes, shedding light on their interaction in freshwater habitats. To provide context for our observation and highlight its rarity, we searched through scientific literature and online sources to generate a comprehensive review of the phenomenon that examines the predatory behaviour of crabs on snakes.

Crepuscular and small but not evolutionary unique species are the reptiles less affected by roadkill in Europe

We extensively reviewed scientific literature and extracted a large dataset with roadkill events for reptile species. We examined 300 articles from 33 European countries, gathering 1688 records of reptiles killed by vehicle traffic. A total of 125 taxa were found documented as roadkill (100 native and 25 exotic species). We calculated each species' occurrence frequency within the database (henceforth ‘relative roadkill frequency'). The relative roadkill of species was strongly and significantly correlated when comparing the whole dataset and the subset of systematic studies. We modelled the inter‐specific variation in relative roadkill frequency across the European reptilian phylogeny concerning species traits, evolutionary uniqueness, and distribution range using a phylogenetic generalized least squares (PGLS) model. Overall, reptile casualties are more pronounced for more closely related species. However, the relative roadkill frequency was unrelated to the level of evolutionary distinctiveness of European reptiles. Additionally, relative roadkill frequency was not correlated to the distribution range but was positively correlated with the species' body mass. The reptiles more frequently cited as road casualties were overall relatively large species: Montpellier snake Malpolon monspessulanus, European grass snake Natrix natrix, and Caspian whipsnake Dolichophis caspius. Additionally, more active species during the crepuscular hours were less affected by roadkill. From a conservation point of view, our results suggest that roadkill frequency is not more significant for evolutionary, more unique reptiles than for other species in Europe, while at the same time, widely distributed species are not the main target of roadkill events. Then, the main causes of roadkill in reptiles must be associated with other factors, such as behavioural traits or density of populations, rather than simply the size of their distribution range.Keywords: evolutionary uniqueness, phylogenetic signal, reptile species, roadkill incidence, wildlife conservation

Virulence factors of Salmonella spp. isolated from free-living grass snakes Natrix natrix.

Salmonellosis associated with reptiles is a well-researched topic, particularly in China and the United States, but it occurs less frequently in Europe. The growth of the human population and changes in the environment could potentially increase the interaction between humans and free-living reptiles, which are an unidentified source of Salmonella species. In this study, we sought to explore this issue by comparing the microbiota of free-living European grass snakes, scientifically known as Natrix natrix, with that of captive banded water snakes, or Nerodia fasciata. We were able to isolate 27 strains of Salmonella species from cloacal swabs of 59 N. natrix and 3 strains from 10 N. fasciata. Our findings revealed that free-living snakes can carry strains of Salmonella species that are resistant to normal human serum (NHS). In contrast, all the Salmonella species strains isolated from N. fasciata were sensitive to the action of the NHS, further supporting our findings. We identified two serovars from N. natrix: Salmonella enterica subspecies diarizonae and S. enterica subspecies houtenae. Additionally, we identified three different virulotypes (VT) with invA, sipB, prgH, orgA, tolC, iroN, sitC, sifA, sopB, spiA, cdtB and msgA genes, and β-galactosidase synthesised by 23 serovars. The identification of Salmonella species in terms of their VT is a relatively unknown aspect of their pathology. This can be specific to the serovar and pathovar and could be a result of adaptation to a new host or environment.

MILK-SUCKING "THIEVES" IN INDO-EUROPEAN FOLKLORE: AN ETYMOLOGICAL ANALYSIS OF ZOONYMS

The paper investigates the etymologies of several species of reptiles, amphibians, and birds whose names draw on the ancient cattle-sucker myths rooted in cultures of Indo-European origin. New or corrected explanations are suggested for a number of animal names, including the Lithuanian žal(k)tỹs 'grass snake', South Slavic *guja 'snake, viper', Hittite akuu̯akuu̯aš 'toad', which seem to confirm a primitive conviction of prehistoric people that some frogs, toads, lizards, snakes, and even birds drink milk and are able to take it directly from udders.

Melanin-based color variation in response to changing climates in snakes.

Melanism, the process of heavier melanin deposition, can interact with climate variation at both micro and macro scales, ultimately influencing color evolution in organisms. While the ecological processes regulating melanin production in relation to climate have been extensively studied, intraspecific variations of melanism are seldom considered. Such scientific gap hampers our understanding of how species adapt to rapidly changing climates. For example, dark coloration may lead to higher heat absorption and be advantageous in cool climates, but also in hot environments as a UV or antimicrobial protection mechanism. To disentangle such opposing predictions, here we examined the effect of climate on shaping melanism variation in 150 barred grass snakes (Natrix helvetica) and 383 green whip snakes (Hierophis viridiflavus) across Italy. By utilizing melanistic morphs (charcoal and picturata in N. helvetica, charcoal and abundistic in H. viridiflavus) and compiling observations from 2002 to 2021, we predicted that charcoal morphs in H. viridiflavus would optimize heat absorption in cold environments, while offering protection from excessive UV radiation in N. helvetica within warm habitats; whereas picturata and abundistic morphs would thrive in humid environments, which naturally have a denser vegetation and wetter substrates producing darker ambient light, thus providing concealment advantages. While picturata and abundistic morphs did not align with our initial humidity expectations, the charcoal morph in N. helvetica is associated with UV environments, suggesting protection mechanisms against damaging solar radiation. H. viridiflavus is associated with high precipitations, which might offer antimicrobial protection. Overall, our results provide insights into the correlations between melanin-based color morphs and climate variables in snake populations. While suggestive of potential adaptive responses, future research should delve deeper into the underlying mechanisms regulating this relationship.

Genetic identification, morphology and distribution of Natrixhelvetica subspecies in southern and western Switzerland (Reptilia, Squamata, Serpentes).

Most of Switzerland is inhabited by the nominotypical subspecies of the barred grass snake (Natrixhelveticahelvetica), which is characterized by mitochondrial DNA lineage E. Only in the northeast of the country, the common grass snake (N.natrix) occurs and hybridizes with N.h.helvetica in a narrow contact zone. However, we discovered that in southern and western Switzerland barred grass snakes representing another mtDNA lineage (lineage C) are widely distributed. Lineage C is typical for Alpine populations of the southern subspecies N.h.sicula. Our microsatellite analyses of the Swiss samples revealed differences between the two subspecies and also a substructure with two clusters in each subspecies. Furthermore, we discovered a contact and hybrid zone of N.h.helvetica and N.h.sicula along the northern shore of Lake Geneva and also confirm that interbreeding with alien common grass snakes (N.n.moreotica, mtDNA lineage 7) occurs there. This finding is of concern for nature conservation and measures should be taken to prevent further genetic pollution. Using morphometrics, we found no differences between the two subspecies of N.helvetica, while N.natrix was slightly distinct from N.helvetica.

Detection of Ophidiomyces ophidiicola in wild barred grass snakes (Natrix helvetica) in the Netherlands

Ophidiomyces ophidiicola is the causative agent of ophidiomycosis (also called snake fungal disease) and has been associated with mycosis in individual snakes and population declines in several North American snake species. While cases of ophidiomycosis from North America have been numerous in the past two decades, reports from Europe remain sparse and are lacking from the Benelux. Between 2017 and 2023, sloughed skins, carcasses and swabs from 284 freeranging, captive and introduced snakes belonging to 22 species were screened for the presence of O. ophidiicola in the Netherlands. Two free-ranging barred grass snakes’ (Natrix helvetica) shed skin sloughs tested positive despite a lack of gross cutaneous signs of disease. These findings are presented in this article. To the authors’ knowledge, this is the first report of the presence of O. ophidiicola in the Netherlands.

Natrix natrix after dark: citizen science sheds light on the common grass snake's nightlife.

Activity patterns in animals are often species-specific, and can be generally categorized as diurnal, crepuscular, or nocturnal. Understanding these patterns provides insight into ecological adaptations and behaviors. The common grass snake (Natrix natrix), one of the most common and widespread European snake species, is traditionally considered diurnal, with scarce evidence of its crepuscular and nocturnal activity. We aimed to document the distribution, environmental conditions, and potential phenotype associations of nighttime activity in N. natrix. We used citizen science data from iNaturalist (1992-2022), Observation.org (2012-2022), together with personal field observations (2010-2023) to collect 127 crepuscular and nocturnal activity records. Most observations occurred between May and August, coinciding with the peak activity period of grass snakes across their distribution range. Statistical analyses revealed no significant difference in mean daily temperatures between crepuscular and nocturnal observations. However, striped individuals displayed nocturnal activity at higher temperatures, consistent with their distribution in warmer regions, but failed to register any difference when tested on a geographic subsample, that accounted for sympatry of the phenotypes. Surprisingly, we found no significant impact of moon presence or moonlight on nighttime activity or age class, contrary to expectations based on other snake species' responses. While our study reveals that nocturnal activity in the common grass snake is geographically widespread, further research is warranted to understand its drivers and ecological implications. This study highlights the value of citizen science platforms for biological and ecological research, offering unparalleled spatial and temporal coverage by their users. In conclusion, our work extends the knowledge of nocturnal behavior in N. natrix and underlines the critical role of citizen science in discovering behavioral aspects of common and widespread species.

Vipers in the state of Acre, western Brazilian Amazon: a review

Snakes of the family Viperidae are distributed in many different ecosystems, generally being the most abundant species in snake surveys and studies on snake assemblages in Brazil. These species are medically important as they can cause snakebites and are responsible for approximately 99% of envenomings in humans in Brazil. Considering the ecological importance of snakes in terrestrial ecosystems, mainly as important predators in food webs, and in public health due to the risks of snakebites, here we review the information available in the literature about vipers in the state of Acre, western Brazilian Amazon. Six species of vipers were already recorded for Acre, with Bothrops atrox being the most abundant, present in various types of habitats and being the main species involved in snakebites. Bothrops bilineatus is the most common snake found in a floodplain forest in the protected area Japiim Pentecoste, a factor probably associated with prey availability. The other four species of vipers (Bothrocophias hyoprora, Bothrops brazili, B. taeniatus and Lachesis muta) are less frequent and associated with unflooded forests. Although we found in the literature several studies involving vipers in Acre, there is a need for more studies on these snakes in the region, addressing their ecology, ethno-herpetological questions and snakebites, including research on their ecology and behavior in the field, genetic variation and differentiation among populations and species, and biochemical composition of venoms.

Venomous snakebites in children: a 10 year experience in South China

Introduction Many studies have focused on snakebites in adults, but very few have described snakebites in children. Methods We reviewed the clinical characteristics and outcomes of children with venomous snakebites aged less than 15 years who presented to a regional medical centre in South China from January 2013 to December 2022. Results A total of 69 envenomed patients were analyzed in our study; 42 (60.9 per cent) patients were male, and 59 (85.5 per cent) reported lower limb bites. Most bites (89.8 per cent) occurred between April and October. Twenty-seven patients received first aid management, and 47 required admission to the general ward. Antivenom was administered to 58 patients, glucocorticoids to 43 patients, antibiotics to 48 patients, and tetanus antitoxin to 40 patients. No fatalities were reported. The most common snake identified was Trimeresurus albolabris. Four were classified as dry bites, 15 as mild, 43 as moderate, and seven as severe. The most common local signs were pain and swelling, while the most common systemic effects were haematological complications. Patients with high severity scores had significantly higher lactate dehydrogenase activities, creatine kinase isoenzyme activities, aspartate aminotransferase activities, D-dimer concentrations, prothrombin times and lower fibrinogen concentrations. In a receiver operating characteristic curve analysis of the values with the highest Youden index, the following cut-offs proved significant: lactate dehydrogenase activity > 248.1 U/L, creatine kinase isoenzyme activities > 17.5 U/L, fibrinogen concentration < 1,455 mg/L, D-dimer concentration > 437.0 µg/L, aspartate aminotransferase activity > 26.1 U/L, and prothrombin time > 15.2 seconds. Discussion This study provides insight into the epidemiology, clinical profile, and management of snakebites in children. Data from the present study were compared with those from our previous adult study. Limitations include that 50.7 per cent of our snakebites were attributed to Trimeresurus albolabris. Therefore, the results of our study may not be generalizable to all snakebites. Conclusion The clinical symptoms were more severe in children than in adults in our previous study. Even though there were no fatalities, close monitoring should be performed to detect haematological and other potentially fatal complications promptly.

Climate change-induced shifts in survival and size of the worlds' northernmost oviparous snake: A 68-year study.

Because of their dependence on ambient temperature ectothermic animals can serve as sentinels of conservation problems related to global warming. Reptiles in temperate areas are especially well suited to study such effects, as their annual and daily activity patterns directly depend on ambient temperature. This study is based on annual data spanning 68 years from a fringe population of Grass Snakes (Natrix natrix), which is the world's northernmost oviparous (egg-laying) reptile, and known to be constrained by temperature for reproduction, morphology, and behavior. Mark-recapture analyses showed that survival probability was generally higher in males than in females, and that it increased with body length. Body condition (scaled mass index) and body length increased over time, indicative of a longer annual activity period. Monthly survival was generally higher during winter (i.e., hibernation) than over the summer season. Summer survival increased over time, whilst winter survival decreased, especially during recent decades. Winter survival was lower when annual maximum snow depth was less than 15 cm, implying a negative effect of milder winters with less insulating snow cover. Our study demonstrates long-term shifts in body length, body condition and seasonal survival associated with a warming climate. Although the seasonal changes in survival ran in opposite directions and though changes were small in absolute terms, the trends did not cancel out, but total annual survival decreased. We conclude that effects of a warming climate can be diverse and pose a threat for thermophilic species in temperate regions, and that future studies should consider survival change by season, preferably in a long-term approach.

Riparian habitat connectivity restoration in an anthropized landscape: A multi-species approach based on landscape graph and soil bioengineering structures.

In urbanized areas, rivers and riparian ecosystems are often the only ecological corridors available for wildlife movement. There, riverbanks are often stabilised by civil engineering structures (dykes, riprap). This can lead to habitat degradation and loss of landscape connectivity. Fascines (willow bundles tied together) could be an alternative to riprap, since they maintain the quality of the natural ecosystems by using native vegetal species instead of rocks, but their potential positive impact needs to be assessed. We proposed a landscape-scale decision-making method for river managers who want to restore banks by transforming riprap into fascines to improve landscape connectivity. We applied our methodology to a case study involving a 25 km-stretch of the Arve River, France. We selected four target vertebrate species based on biological traits to cover a wide range of dispersal capacities. For each species, we used landscape graphs to assess habitat connectivity under different contrasted riverbank scenarios. Scenarios included replacing all-natural banks with ripraps or replacing all ripraps with fascines. In addition, we systematically tested the effect of replacing individual 100 or 500 m sections of ripraps by fascines, to locate where riverbank restoration would maximize connectivity gain. The four species selected responded very differently to the scenarios (up to +14% and +46% change in Probability of Connectivity for common toads and Eurasian beavers, respectively, 0% for common sandpipers and barred grass snakes). The restoration of specific riverbank sections could result in important gains in PC (up to +33% for one single section for one species) but no section maximized connectivity gain for all the target species.

Characterisation, prevalence and severity of skin lesions caused by ophidiomycosis in a population of wild snakes

Ophidiomycosis is an emerging infectious disease affecting wild snakes in the Northern Hemisphere. Recently confirmed in Great Britain, the prevalence, severity and significance of ophidiomycosis has yet to be characterised in free-living snakes at a population level in Europe. Therefore, a population of barred grass snakes (Natrix helvetica) in eastern England was monitored for three seasons (May 2019 to October 2021), to investigate the prevalence (25.5%; 191/750 snakes) and severity of skin lesions and their aetiology. The most frequently observed skin lesion characteristics were changes in scale colour, crusting, and scale margin erosion. The majority of such lesions (96.9%; 185/191 snakes) was observed on the ventral surface along the length of the body. The severity of skin lesions was considered mild in more than half of the cases (53.1%; 98/191 snakes). Predominantly, skin lesions were observed in adult snakes (72.8%; 139/191 snakes). Combined histological examinations and qPCR tests of skin lesions from N. helvetica sloughs and/or carcasses confirmed a diagnosis of ophidiomycosis. Further targeted surveillance, supported by molecular and histological examinations to confirm skin lesion aetiology, is required to determine the extent to which our findings reflect the occurrence of ophidiomycosis in populations within wider landscapes.

Herbal Antivenins as an Eye Opener Towards Snake Envenomation

Snakebites are the most neglected health problem in India. Antivenoms are used in treatment, but since they are mostly unavailable, the mortality rate is even higher in rural areas. The currently available antivenoms are monovalent and polyvalent and are effective against four common snakes in India. In this article, we have reviewed the herbal antivenoms against specific snake species along with their in vitro and in vivo studies and the phytochemicals responsible for antivenom activity. These phytochemicals have been scientifically proven to neutralize the effects of deadly snake venoms and can be used as an adjunct to anti snake venom therapy or can be effectively used to provide proper first aid in snake bite cases to decrease the mortality rates. Studies have been conducted on plant extracts to explore their antivenom activity along with anti myotoxic, anti haemorraghic as well as anti inflammatory activity. These herbs are used ethnopharmacologically by traditional healers for snake envenomations. The review here is a comprehensive approach to the phytochemicals having anti venom activity, however, further studies are needed to gain in-depth knowledge.

Phytochemical characterization and phospholipase A2 inhibitory effect of Vitex negundo L. root extracts

Ethnopharmacological relevanceSnake bites are a critical health issue in many parts of the world particularly in Asian countries lacking efficient health facilities in rural areas. Cobra is the most common snake type in Asia and is responsible for a large number of mortalities particularly in rural areas. Plants are usually considered the most effective and easy-to-approach treatment for snake bites in rural areas of various countries. Vitex negundo L. is an important medicinal plant traditionally used to treat snake bite envenomation in many countries of Asia. Aim of the studyFrom literature survey of plants traditionally used in the treatment of snake bites in Asian countries including India, Pakistan and Sri Lanka, roots of V. negundo were selected for the present study. Anti-snake venom potential of its roots was assessed through various in vitro assays targeting the phospholipase A2 enzyme. Materials and methodsV. negundo roots were sequentially extracted in different organic solvents to get fractions and in methanol to get total extract. The extracts were evaluated for phospholipase A2 (PLA2) inhibitory potential through inhibition of venom-induced hemolysis, ADP-induced platelet aggregation, PLA2-induced fatty acid hydrolysis and anticoagulant effect of cobra venom. Antioxidant power was determined using DPPH and superoxide radical scavenging assays. GC-MS and HPLC analysis was performed for the total methanol extract. ResultsStrong PLA2 inhibitory effect was observed for all the extracts. The ethyl acetate, acetone and methanol fractions significantly inhibited toxic effects of cobra venom under in vitro conditions. Radical scavenging potential of these fractions was also significantly high as compared to non-polar fractions in both DPPH and superoxide scavenging assays. Phytochemical analysis indicated high phenolic and flavonoid contents in these fractions. GC-MS and HPLC analysis of total methanol extract confirmed the presence of bis(2-ethylhexyl) phthalate, phenol, o-Guaiacol, palmitic acid-methyl ester, methyl stearate, quercetin and kaempferol in the plant. ConclusionThe study concluded that the roots of V. negundo, particularly their polar extracts, have strong PLA2 inhibitory effect against cobra venom confirming their traditional use to manage snake bites. The roots of this plant can be further studied for isolation of plant-based antisera.

The Role of the Grass Snake Natrix natrix (Reptilia, Colubridae) in the Transfer of Polyunsaturated Fatty Acids from Aquatic to Terrestrial Ecosystems to Land

As a result of analyses of fatty acid (FA) composition in the grass snake Natrix natrix and its food objects, tadpoles and metamorphs of two amphibian species: the moor frog Rana arvalis and the Pallas spadefoot toad Pelobates vespertinus, it was shown for the first time that the high total content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in the biomass of the snakes indicates its important role in the transfer of these essential substances from aquatic ecosystems to land. It was found that, since food sources of DHA in terrestrial ecosystems are absent, its high level in R. arvalis metamorps and grass snakes may be provided only by synthesis from biochemical precursors contained in food of aquatic origin.

Snakebites in the Americas: a Neglected Problem in Public Health

Abstract Purpose of Review We explored the current priority given to snakebites in 26 countries of the Americas. To describe the epidemiological characteristics of the snakebites in the Americas and the Caribbean, we looked at information collected from epidemiological sources, publications, and available from PubMed, SciELO, and LILACS. In the case of Honduras, some gray literature (theses and conference abstracts) was obtained through local networks. We also aimed at obtaining any reference made in those reports with regard to the most common snake species in the region and their toxin and the physical and mental disability in snakebite victims. Recent Findings Many countries do not keep official reports of the snakebite incidents. In a few countries, growing knowledge of venom toxicology is leading to research and development of new antivenoms. Additionally, interest is increasing in the identification of natural treatment for symptoms caused by snake venoms, especially inflammation, pain, and blood loss. There are opportunities to undertake rigorous examination of traditional treatments, which could be incorporated to the standard of care. Summary Snakebite surveillance needs improvement in several countries, and access to prompt treatment needs to be facilitated. With a few exceptions, scientific research is scarce in most Latin American countries. For prevention and management initiatives, it is important to highlight that the typical profile of the snakebite victim is a young male farmer with low literacy.

THE ROLE OF THE GRASS SNAKE &lt;i&gt;NATRIX NATRIX&lt;/i&gt; (REPTILIA, COLUBRIDAE) IN THE TRANSFER OF POLYUNSATURATED FATTY ACIDS FROM AQUATIC TO TERRESTRIAL ECOSYSTEMS TO LAND

As a result of analyses of fatty acid (FA) composition in the grass snake Natrix natrix and its food objects, tadpoles and metamorphs of two amphibian species: the moor frog Rana arvalis and the Pallas’ spadefoot Pelobates vespertinus, it was shown for the first time that the high total content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in the biomass of the snake indicates its important role in the transfer of these essential substances from aquatic ecosystems to land. It was found that since food sources of DHA are absent in terrestrial ecosystems, its high level in R. arvalis and grass snakes may be provided only by synthesis from biochemical precursors contained in food of aquatic origin.

Severity of a Vipera palaestinae envenomation objective findings associated with a complicated hospitalization course following a Vipera palaestinae bite

The most common snake in Israel, responsible for most snakebites is Vipera palaestinae (VP). Envenomation signs and symptoms vary from local manifestations to systemic reactions that may end with death. Antivenom treatment, given to high-risk patients, reduces complications and mortality but carries risks. As of now, there is no standardized protocol for adults bitten by VP based on objective clinical and laboratory findings. We conducted A retrospective analysis of 159 patients admitted to two large tertiary care institutions in the center (Hadassah University Medical Center) and south (Soroka University Medical Center) of Israel with Vipera palaestinae bites during 1990–2017. Epidemiological and clinical data were extracted, and the patients were divided into two groups based on hospitalization time (over or under 48 h). 159 patients were included in this study. The average hospitalization time was 66.1 h, with 49.7% of patients admitted over 48 h. The main factors that statistically correlated with a longer hospitalization time were: Male gender, lower extremity bite, platelets lower than 150 K at presentation, leukocyte count of over 10 K at presentation and elevated D-Dimer levels. This study provides factors which are associated with a severe VP envenomation. These clinical or laboratory findings (along with accompanying clinical symptoms) are associated with a higher risk of a prolonged hospitalization with more complications and may require a more intensive treatment and monitoring.