Nose-horned viper

Appearance

V. ammodytes grows to a maximum total length of 95 cm, although individuals usually measure less than 85 cm. Maximum length also depends on race, with northern forms distinctly larger than southern ones. According to Strugariu, the average total length is 50–70 cm with reports of specimens over 1 m in total length. Females are usually larger and more heavily built, although the largest specimens on record are males.

The head is covered in small, irregular scales that are either smooth or only weakly keeled, except for a pair of large supraocular scales that extend beyond the posterior margin of the eye. 10-13 small scales border the eye, and two rows separate the eye from the supralabials. The nasal scale is large, single, and separated from the rostral by a single nasorostral scale. The rostral scale is wider than it is long.

The most distinctive characteristic is a single "horn" on the snout, just above the rostral scale. It consists of 9-17 scales arranged in 2 transverse rows. It grows to a length of about 5 mm and is actually soft and flexible. In southern subspecies, the horn sits vertically upright, while in "V. a. Ammodytes" it points diagonally forward.

The body is covered with strongly keeled dorsal scales in 21 or 23 rows at mid-body. The scales bordering the ventrals are smooth or weakly keeled. Males have 133-161 ventral scales and 27-46 paired subcaudals. Females have 135-164 and 24-38 respectively. The anal scale is single.

The color pattern is different for males and females. In males, the head has irregular dark brown, dark gray, or black markings. A thick, black stripe runs from behind the eye to behind the angle of the jaw. The tongue is usually black, and the iris has a golden or coppery color. Males have a characteristic dark blotch or V marking on the back of the head that often connects to the dorsal zigzag pattern. The ground color for males varies and includes many different shades of gray, sometimes yellowish or pinkish gray, or yellowish brown. The dorsal zigzag is dark gray or black, the edge of which is sometimes darker. A row of indistinct, dark spots runs along each side, sometimes joined in a wavy band.

Females have a similar color pattern, except that it is less distinct and contrasting. They usually lack the dark blotch or V marking on the back of the head that the males have. Ground color is variable and tends more towards browns and bronzes, such as grayish brown, reddish brown, copper, "dirty cream", or brick red. The dorsal zigzag is a shade of brown.

Both sexes have a zigzag dorsal stripe set against a lighter background. This pattern is often fragmented. The belly color varies and can be grayish, yellowish brown, or pinkish, "heavily clouded" with dark spots. Sometimes the ventral color is black or bluish gray with white flecks and inclusions edged in white. The chin is lighter in color than the belly. Underneath, the tip of the tail may be yellow, orange, orange-red, red, or green. Melanism does occur, but is rare. Juvenile color patterns are about the same as the adults.

Naming

Common names: Horned viper, long-nosed viper, nose-horned viper, sand viper, sand adder, common sand adder, common sand viper, sand natter.

Distribution

Vipera ammodytes ammodytes: SE Bosnia, S Bulgaria
Vipera ammodytes montandoni: Turkey, E Bulgaria, Romania
Vipera ammodytes meridionalis: Albania, Greece (incl. Corfu = Corfou, Paros, Tinos), S Serbia, Romania, S Bulgaria, European Turkey

Status

This species is listed as strictly protected under the Berne Convention.

Behavior

This species has no particular preference for its daily activity period. At higher altitudes, it is more active during the day. At lower altitudes, it may be found at any time of the day, becoming increasingly nocturnal as daytime temperatures rise.

Despite its reputation, this species is generally lethargic, not at all aggressive, and tends not to bite without considerable provocation. If surprised, wild specimens may react in a number of different ways. Some remain motionless and hiss loudly, some hiss and then flee, while still others will attempt to bite immediately.

"V. ammodytes" hibernates in the winter for a period of 2 to 6 months depending on environmental conditions.

Habitat

The common name "sand viper" is misleading, as this species do not occur in really sandy areas. Mainly, it inhabits dry, rocky hillsides with sparse vegetation. Not usually associated with woodlands, but if so it will be found there around the edges and in clearings. Sometimes found in areas of human habitation, such as railway embankments, farmland, and especially vineyards if rubble piles and stone walls are present. May be found above 2000 m at lower latitudes.

Reproduction

Before mating, the males of this species will engage in a combat dance, similar to adders. Mating takes place in the spring, and one to twenty live young are born in late summer or fall. At birth, juveniles are 14–24 cm in total length. This species is ovoviviparous.

Food

Primarily feeds on small mammals and birds. Juveniles apparently prefer lizards. Feeding behavior is influenced by prey size. Larger prey are struck, released, tracked, and swallowed, while smaller prey is swallowed without using the venom apparatus. Occasionally, other snakes are eaten. There are also reports of cannibalism.

Defense

This is likely the most dangerous snake to be found in Europe. In some areas it is at least a significant medical risk.

The venom can be quite toxic [based on tests conducted solely on mice], but varies over time and among different populations. Brown gives an LD50 for mice of 1.2 mg/kg IV, 1.5 mg/kg IP and 2.0 mg/kg SC. Novak "et al." give ranges of 0.44–0.82 mg/kg and IV and 0.19-0.64 mg/kg IP. Minton states 6.6 mg/kg SC.

The venom has both proteolytic and neurotoxic components and contains hemotoxins with blood coagulant properties, similar to and as powerful as in crotaline venom. Other properties include anticoagulant effects, hemoconcentration and hemorrhage. Bites promote symptoms typical of viperid envenomation, such as pain, swelling and discoloration, all of which may be immediate. There are also reports of dizziness and tingling.

Humans respond rapidly to this venom, as do mice and birds. Lizards are less affected, while amphibians may even survive a bite. European snakes, such as "Coronella" and "Natrix", are possibly immune.

"V. ammodytes" venom is used in the production of antivenin for the bite of other European vipers and the snake is farmed for this purpose.