Russel’s Viper

Russel’s viper is a highly venomous snake that inhabits areas in the Indian subcontinent and is one of the top culprits of snakebite envenomations in the region.

This four to six-foot-long viper is reputed to be aggressive, and is certainly willing to bite; however, they’re more interested in eating the rats and mice that follow humans and their cities.

3 Amazing Facts

• In Myanmar, Russel’s viper is responsible for up to 80% of the snakebites reported; in India, 43% of the snakebites.
• The rough-scaled sand boa (Erix conicus) has mimicked the appearance of this viper to gain some protection from predators.
• It’s one of a handful of viperine species without heat-sensing organs that can respond to thermal cues.

Scientific Name and Classification

This snake is a viper in the Viperidae family; they were described by George Kearsley Shaw and Frederick Polydore Nodder in 1797 as Coluber russelii. They named the snake after Patrick Russell, a Scottish surgeon and herpetologist who worked in India. It was Russell who presented the first specimen to the British Museum after he had written about it in An Account of Indian Serpents, Collected on the Coast of Coromandel, published in 1796.

Later, it was reclassified into Daboia russelii, the genus name is based on a Hindi word that means either “the lurker,” or “that lies hid.” In different languages it has different names; for example, it goes by chandroborha in Bengali and Lindu in Manipuri and Meitei.

The spelling of the scientific name, Daboia russelii, is still sometimes a point of contention because Russell spelled his last name with two L’s at the end. Whereas Shaw and Nodder (1791) misspelled it from the start, others such as Zhao and Adler (1993) favor correcting the spelling with the second L.

Appearance and Description

This snake has a triangular, flattened head with an obvious neck. Its snout is blunt, raised, and rounded with large nostrils, each in the center of a single nasal scale. The crown of its head has irregular scales that appear fragmented. Its eyes are large with flecks of gold or yellow with elliptical pupils. It often has several pairs of replacement fangs, as the active fangs break frequently.

Russel’s viper has a rounded, thickset body with strongly keeled dorsal scales; it also has a short tail. This snake measures 4 to 5.5 feet long; juveniles are born at 8.5-10.2 inches. Its color pattern is striking. A base color of dark yellow, tan, or brown with dark spots that run the length of its body. There are three sets of spots; those on the sides are smaller than the spots on its back, and they’re usually outlined in black. An added white or yellow rim around the spots makes them stand out even more. On top of its head are two large spots, and on the side of its head is a dark streak bordered with a lighter color that starts behind its eye.

This species doesn’t have heat-sensing pits. However, it seems to respond to heat similarly to a pit viper. The identity of the heat-sensing organ is unknown at this point, but the nerve endings in the supranasal sac are similar to those found in the heat-sensing organs of other snakes.

Russel’s Viper Look-Alikes

Mimicry is something that seems to happen when one animal is extremely successful in its given niche. In this case, Russel’s viper is successful and has few predators aside from humans, mongooses, and birds of prey, so another snake has mimicked its appearance. This snake is the rough-scaled sand boa (Erix conicus). On the surface, the color pattern on the boa looks like that of Russel’s viper. However, the boa is completely harmless.

This mimicry is common in nature. Another example is how the deadly North American coral snakes (Micrurus fulvius) and harmless scarlett king snakes (Lampropeltis elapsoides) look alike. To the inexperienced, they look almost identical, but they’re very different. The almost, but not quite, matching pattern on the harmless animal affords it some level of protection from predators.

Behavior and Humans

Many say that Russel’s viper is aggressive or ill-tempered. It is also notorious for not moving when someone comes near, then biting that individual when he or she comes too close. Nevertheless, multiple videos featuring snake catchers trying to relocate a snake show it trying to escape and snapping only when it can’t get away. They have been seen approaching people, but may simply be curious.

However, in Myanmar, about 70-80% of the snakebites reported are from a Daboia genus snake such as Russel’s viper or the eastern Russel’s viper. Juveniles of the species are especially jumpy and nervous, and more likely to bite or snap than adults.

Aggressive or not, the high number of encounters with people coupled with the fact that this snake is likely to bite if provoked or startled is a dangerous combination.

Diet

This snake’s diet mainly consists of rodents, but it also eats small reptiles, scorpions, land crabs, and other arthropods. Juveniles are cannibalistic and usually active at dawn and dusk. They actively forage for small lizards and snakes until they’re big enough to take rodents. These nocturnal foragers alter their behavior when the weather is cooler, coming out during the daytime hours.

Location

Russel’s vipers live in India, Bangladesh, Nepal, Pakistan, and Sri Lanka. They are highly venomous and extremely common in many parts of their range. These snakes prefer open grasslands or bushy areas but avoid wet, marshy areas. They sometimes occur in scrub jungles and on farmland but are most common in coastal lowlands and hills with suitable cover.

Due to habitat loss and the rodents that follow human settlements, Russel’s vipers also make their homes in urban areas and settlements. As much as it follows the rodents, it generally tries to avoid areas with large populations of people.

Reproduction

According to observation, Russel’s vipers become sexually mature by their second or third year. This species is ovoviviparous; that is, it gives live birth after the mother incubates the young internally until they’re ready. These vipers generally mate early in the year, but pregnant females are found all year round. The mother carries the babies for more than six months, and they’re usually born between June and July, but depending on when the mother mates, they could be born any time between May and November.

This snake breeds easily and in large numbers. Litters numbering 20-40 are common, but they can range between 5 and 50; the largest recorded litter was 75.

Population and Conservation Status

The IUCN Redlist of Threatened Species lists this snake as a species of least concern. It’s unlikely to be declining fast enough for a more threatened category, and it is widespread across its territory. That and the ease with which it breeds puts it at lower risk. Several countries have legal protection in place for the viper, including India and Sri Lanka.

Like many species, Russel’s viper is common in some areas but declining in others. It has a somewhat fragmented population, but that is not severe enough to cause concern as yet. As cities and towns grow, the snake’s natural habitat shrinks, so it follows its favorite prey into the urban sprawl, driving it right into where it’s going to run into people. When people see it, they often kill them or try to drive the snakes off.

Venom

A bite from this snake is bad news. It is one of India’s big four venomous snakes along with the Indian cobra (Naja naja), common krait (Bungarus caeruleus), and saw-scaled viper (Echis carinatus). They are all very willing to bite and are deadly.

Its venom is a potent cocktail containing a large percentage of hemotoxins that cause several problems in the body. Symptoms include:

• Pain at the site, immediately followed by swelling of the affected body part.
• Bleeding from the gums and in the urine is common, and sputum may contain blood within 20 minutes of the bite.
• Then, the victim’s blood pressure and heart rate fall.
• Blood clots may form also.
• Tissue necrosis also occurs, but is usually limited to the immediate area around the bite.
• About one-third of its victims experience vomiting and facial swelling.
• Kidney failure also occurs in about 25-30% of cases.

A victim can experience severe pain for 2-4 weeks, but most of the local swelling peaks in the first 48-72 hours. One to two weeks after the bite, a victim may still die from septicemia or kidney, respiratory, or cardiac failure.

Early treatment is vital and can prevent or dramatically reduce the chances of developing potentially lethal complications.