Introduction
The Viperidae are one of the most interesting and diverse snakes families in the western Palearctic and, due to their rather complicated taxonomy, intimidating appearence and venom potency, they have been the subject of very extensive research. The Nose-horned viper, potentially one of the most extensively studied european snakes and a favorite among herpetologists and herpers, is the most widespread viper species in Greece. It extends from parts of NE Italy and S Austria to E Romania and south to almost all of the Balkan peninsula, as well as parts of NW Turkey and occurs on several Ionian & Aegean islands, where it is represented by a handful of subspecies and clades. The species shows huge genetic variability among differerent populations, with recent phylogenetic studies suggesting new clades and subclades that are not in agreement with the current taxonomy, leaving room for mass changes in the near future. Its latin name, ammodytes, which comes from the greek words 'ámmos' [sand] and 'dýtes' [diver] was inspired by the iconic horn on its snout, which might give the impression that it is used to keep sand out of the snake's eyes – however, the species does not dive in sand like African vipers of the genus Cerastes do. The nose-horned viper has become the subject of numerous modern myths and resentment among locals, with its common name “οχιά” (pronounced “ohiá”) being synonymous with evil and treason. However, while the snake is venomous, death from envenomation is highly unlikely and its reputation is largely underserved as it is not an aggressive animal.
Description
Usually up to 65cm TL, rarely reaching 95cm. Island populations commonly smaller, with pygmy forms occuring on some of the Cyclades and Sporades islands. Thick-bodied snake, with a large, triangular head due to the presence of venom glands, one behind each eye. Head scales small and irregular, exluding the supraocular scales, which are large and defined. Eye pupil vertical during daytime. The tongue is black. The tail is very short and ends abruptly. Coloration and pattern highly variable among different subspecies and populations. Dorsal coloration ranging from silver grey or whitish to yellow, reddish, brown or dark grey, with a very distinct light or dark brown to black, either continuous or interrupted zig-zag line of varying shapes running across the back. Round markings or bars often present on the flanks. Uniform (concolor) and melanistic individuals have been recorded, although probably extremely rare. Males usually with greyish shades and high contrast between pattern and dorsal coloration, females commonly more dull with a rather faded pattern. Dark pattern on top of the head typically present on males. Ventral coloration silver–whitish, with irregular or semi-regular dark spots of very wide variability. Individuals belonging to the subspecies V. a. montandoni & V. a. meridionalis often exhibit a green or yellow tail tip, while individuals of V. a. ammodytes may have a reddish tail tip. Very characteristic appearence due to a soft horn made of 9–22 scales on top of the snout, of which the purpose remains unknown and has been puzzling herpetologists for centuries. Although extremely rare, individuals lacking a horn have been recorded. Typically 21 rows of strongly keeled dorsal scales in mid-body.
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| Adult female, Attica (C) Plato Stefanopoulos |
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| Adult female, Sporades (C) Stamatis Kalogiannis |
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| Adult female, Sporades (C) Stamatis Kalogiannis |
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| Adult female, South Boeotia (C) Plato Stefanopoulos |
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| Adult male, Corinthia (C) Plato Stefanopoulos |
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| Juvenile (yearling), Achaea, Peloponnese (C) Plato Stefanopoulos |
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| Juvenile, Magnesia (C) Plato Stefanopoulos |
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| Adult male, Attica (C) Plato Stefanopoulos |
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| Young male, Sporades (C) Stamatis Kalogiannis |
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| Head detail; note the distinct horn made of scales on the top of the snout (C) Stamatis Kalogiannis |
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| Young female, Serrai (C) Plato Stefanopoulos |
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| Adult male, Pieria (C) Plato Stefanopoulos |
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| Adult male, Attica (C) Plato Stefanopoulos |
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| Juvenile, Pieria (C) Plato Stefanopoulos |
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| Very large adult male, approx. 80 cm TL, Central Greece (C) Plato Stefanopoulos |
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| Young adult male, Central Greece (C) Plato Stefanopoulos |
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| Large adult male, Central Greece (C) Plato Stefanopoulos |
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| Young male, Achaea (C) Plato Stefanopoulos |
Habitat
Favours warm and sunny slopes with rocky substrate and some vegetation cover, but generally inhabits all types of mediterranean habitats; rocky outcrops, maquis, phrygana, agricultural land, gardens, abandoned olive groves, hardwood, conifer and mixed forests and forest edges, riparian zones,wetlands and even alpine meadows. Tolerates thermo-xeric conditions but can also be found in lush and humid areas about as frequently. From sea level to 2,500m asl.
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| Rocky terrain with phrygana bordered by Quercus ilex forests – habitat of Vipera ammodytes |
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| Abandoned olive grove with rich undergrowth, shrubs and stones – habitat of Vipera ammodytes |
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| Olive grove with stonewalls, bordered by aleppo pine – habitat of Vipera ammodytes |
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| Agricultural land with olive groves and vineyards – habitat of Vipera ammodytes |
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| Olive groves bordering hillsides with phrygana – habitat of Vipera ammodytes |
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| Maquis shrubland and phrygana on a steep hillside – habitat of Vipera ammodytes |
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| Open grassland with low trees and bushes bordering hillsides – habitat of Vipera ammodytes |
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| Adult female in its habitat, Attica (C) Plato Stefanopoulos |
Biology
Overwinters underground but, in low to mid altitudes, brumation is not continuous and it can emerge and become active even in cold conditions. It is also important to note that it is one of the most winter-active snake species in Greece, and it is not uncommon to observe individuals crossing roads in December or January. Mating takes place in spring and males will often battle with each other to establish their territory while competing for females. V. ammodytes is ovoviviparous and gives birth to up to 20 young that usually measure about 10-12 cm. Birth takes place in August–October. Gestation and birth is extremely energy-costly for females and is perhaps the reason for some mortality. Therefore, females will reproduce once every two or even three years. Sexually mature individuals as small as approx. 44 cm in the mainland, and sexual maturity is reached in the 4th or 5th year of age at a similar size for both sexes. It will often bask on top of rocks or fallen leaves where it “disappears” with its cryptic coloration. It may also climb shrubs and small trees. It is not a particularly graceful snake in its movement, and it is characterized by its abrupt, jerky motions, as well as the characteristic “side-winding” motion it utilizes to traverse flat surfaces without anchors such as roads. It is not particularly fast-moving. Temperatures and time of activity vary immensely, but the general consensus is that it is diurnal in the cooler part of the spring and mainly crepuscular or nocturnal in the summer months. Nevertheless, we have observed adults active at night in November in temperatures as low as 16-17C, as well as in relatively high temperatures in the daytime in early summer. The snakes’ prey also varies considerably, and ranges from arthropods, to lizards, to small mammals, to birds, to even amphibians in some cases. Juveniles and small adults have been observed consuming Orthoptera and Scolopendra centipedes, as well as small wall lizards and geckos. Larger individuals will mainly take rodents such as mice as well as small birds. Larger and/or fast prey is not hunted actively and the snakes will find trails used by rodents and ambush them. The green or red tail tip that is apparent on some individuals, specifically smaller ones is said to be used as a caudal lure. V. ammodytes has long, hollow, movable fangs (solenoglyphous) attached to venom glands, that are used to inject prey like hypodermic needles. Larger prey is bitten, envenomated and released immediately. After the prey item collapses, the snake will follow its scent trail and consume it. When faced with a potential predator, its first instinct is to lie still, as it is not very fast-moving and its camouflage often suffices to make it invisible to predators. It will usually bite if grabbed or stepped on. If it is found in the open, its first instinct when approached is to get away. When its escape route is blocked, it will coil in a defensive position and strike if approached within less than about half a meter. In some cases, the snake may continue moving with its head and neck reared up and its neck flattened while hissing. Bites on humans do not always result in envenomation as venom production requires a lot of energy and the snake’s priority is to use it on prey items, so the snake does its best to avoid using it on us. The amount of venom injected is also controlled by the snake. Unlike local myths, the nose-horned viper is not at all an aggressive animal and it will never seek out to bite humans.
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| Adult male in defensive posture |
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| Large males in a territorial fight, Euboea (C) Plato Stefanopoulos |
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| Large males in a territorial fight, Euboea (C) Plato Stefanopoulos |
Venom and bite symptoms
Vipera ammodytes has the most potent venom among all Vipera species. Similarly to most European vipers, the venom of the species is a cocktail of mainly proetolytic enzymes, with a less neurotoxic effect. It causes blood coagulation, hemoconcentration and hemorrhage and symptoms may include pain, swelling, hemorrhagic edema, hypotension, nausea, ecchymosis, tachycardia, swelling of lymph nodes, fever, vomiting and blurred vision. Bites from V. ammodytes are of significant medical risk but are rarely lethal if treated immediately in a hospital. The venom of the species is also used in the production of antivenin for the bite of European vipers.
Distribution
Very widespread, found throughout all of mainland Greece and on dozens of the Ionian and Aegean islands; Euboea, Corfu, Lefkada, Kefallonia, Ithaca, Thasos, Northern Sporades (Skiathos, Skopelos, Alonissos and other islets) and Cyclades (e.g. Andros, Tinos, Naxos, Paros, Mykonos, Iraklia, Koufonisi, Syros, Ios). Absent from the Dodecanese archipelago and from the NE Aegean where it is replaced by the Ottoman viper (Montivipera xanthina). Reports about Vipera ammodytes co-existing with Montivipera xanthina on Samothrace have not been confirmed.
Subspecies V. a. ruffoi and V. a. gregorwallneri have been synonimized with the nominate V. a. ammodytes, while currently recognised subspecific taxa (V. a. ammodytes, V. a. montandoni, V. a. meridionalis) shall rather be considered invalid since they do not reflect the actual genetic diversity of the species. Based on recent phylogenetic studies (see Ursenbacher et al. 2008, Čubrić et al. 2019), the populations of V. ammodytes can be divided in a total of 7 clades, 4 of which occur within Greece. Vipers from the Northern Sporades are here classified as of "no data" (see map below).
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| Distribution of revealed Vipera ammodytes phylogenetic clades in Greece. Islands colored in gray indicate lack of data. |
