| 1 | France’s deadliest snake |
France has 12 snake species in total, and of those, 3 are venomous. Only one can be the deadliest, and that award goes to the asp viper (Vipera aspis), a close relative of the common adder (Vipera berus) that stalks the English countryside.
The asp viper is a small snake, ranging from 40 to 85cm. It’s easy to differentiate from nearby snakes, with an upturned nose and a tail that thins significantly towards the end. It’s one of many snakes with freaky vertical pupils (joining the rattlesnake family), and its maximum lifespan in the wild is 18 years.
The asp viper falls well short of the blue krait or king cobra, but still bites an average of 300 French people per year. In Italy, the asp viper is responsible for 90% of fatal snakebites. 4% of untreated bites are fatal, and there’s several documented cases to report, including a horrible unlucky 45 year old man who died within 5 minutes in July 2014. This man was otherwise healthy, and was only bitten on the thigh.
| 2 | A country snake |
Within France, the adder occupies the northern 25% of the country, as they’re better adapted to cool temperatures. The asp viper occupies the entire lower 75% of France, except for small stretches of the Mediterranean coastline. Across Europe, the asp viper also inhabits the alps, the Pyrenees of northern Spain, and the whole of Italy. Its favourite domains are easily thick hedges, particularly poorly maintained ones with grasses at the base, which they use as a sort of corridor. The more intensely farmed a landscape is, the more this venomous snake will disappear from it. Asp vipers are found in forests occasionally, but hate the darkest, gloomiest ones where rays of light can barely penetrate the leaves.
Unlike the four-lined snake, asp vipers aren’t creatures of the water; they’re only rarely spotted swimming. They prefer dryer regions, though not ones which are parched like a bone.
Occasionally, the asp viper will stray to extremely high altitudes. The Pyrenees record was 2930 metres, while the alps record stands at 3300m (Valais in Switzerland).
| 3 | Stages of an asp viper strike |
Asp viper venom has an LD50 score of 1.01mg in mice, almost matching the 0.9mg of a king cobra. In France, the symptoms have 3 different gradings of severity, with grade 1 being purely local. An asp viper bite lasts for merely 0.3 seconds, so if you fall victim to its bitey talents, then you’ll only notice a short sharp pain. A few minutes later, the flesh surrounding the bite will swell, followed by painful blistering.
These symptoms normally fade after 24-72 uncomfortable hours, and this is where most asp viper bites stop. But grade 2 is when the effects become systematic. Within 24 hours, the victim experiences vomiting, abdominal pain, and general malaise. The earliest systematic effect, a drop in blood in pressure, can occur within 30 minutes.
Finally, there’s grade 3, the grade where death is an everpresent risk. The final cause of death is usually kidney failure, but other advanced symptoms include low oxygen levels, severe bleeding (or sometimes completely halted bleeding), and lung lesions.
One relatively unique effect of asp viper venom is temporary blindness, caused by the venom destroying eye cells.
| 4 | Particularly deadly near Nice |
Asp viper venom isn’t famous for its neurotoxins, the class responsible for muscle weakness, paralysis and lung failure in other snakes. But in the 1990s, reports began to trickle in from southeast France of bites with unusual effects, including drooping eyelids (ptosis) and difficulty swallowing.
These were members of the usual Vipera aspis aspis subspecies common across France, so there was no reason for its venom to be different. Herpetologists arrived on the scene, and discovered that in narrow areas, the asp viper’s venom did have neurotoxins. In Nice, these included ammodytoxins and vaspin, while in Montpellier, they included phospholipase A2. The venom profile was far closer to the horned viper of southern Europe, the most feared viper on European soil.
The asp vipers in the vast majority of France (and Switzerland and Italy) lacked these neurotoxins, but in terms of physical appearance, this supertoxic subpopulation was nearly indistinguishable. This is one local talent the tourism boards of Nice probably won’t mention in their glossy brochures.
| 5 | Diet of an asp viper |
Asp vipers are addicted to the furry flavour of voles, and specifically the common European vole (Microtus arvalis). One report stated that 98% of their diet consists of this small mammal. This vole is a small, indistinct animal which weighs just 1 pound and has an average body length of 10cm. It inhabits all of Europe except for Scandinavia and the UK, and scurries through the same thick hedges where asp vipers love to hang out.
Asp vipers favour voles so heavily that their population levels are closely intertwined; when voles fall, so do the snakes. Asp vipers will also eat field mice and the vole’s cousin the shrew if they get the chance, and sometimes lizards and birds, not being exclusive mammal hunters. Baby asp vipers acquire 81% of their food from reptiles, until they reach the magic length of 35%.
Meanwhile, asp vipers themselves are hunted by falcons and members of the Corvidae bird family (crows, rooks, ravens). This is partly why they favour the thick protection of tangled hedgerows.
| 6 | They’re not scheming to kill |
In India, there are villages which are under constant attack from king cobras and blue kraits, not to mention the unusually aggressive mugger crocodile lurking in rivers. The asp viper doesn’t subscribe to this mentality – instead, it’s part of the defensive school of snakes. Asp vipers are rarely aggressive towards passersby, and they definitely won’t slither up a toilet in a malicious attempt to bite the person sitting on it. They even move through the undergrowth quite slowly.
The danger usually happens when nature mad explorers pick them up. Unlike grass snakes, which usually play dead, this usually spooks the asp viper and sends it into an aggression spiral.
Never underestimate an asp viper; even babies (neonates) are capable of triggering a serious medical episode. Another death happened in July 1996, when a 69 year old French woman was bitten on the thigh. She didn’t die within 5 minutes like the man above, but her symptoms rapidly progressed to stage 3, and she later died in hospital, where antivenom couldn’t save her.
| 7 | A particularly endangered snake |
Asp vipers were once abundant across most of France. Technically, their range still covers most of the country, but farmers report an increasing rarity over the last 50 years. Within their range, they’re withdrawing to ever more isolated pockets.
It’s no mystery why this has happened. It was a deliberate extermination, initiated on August 22nd 1863 when the Deux-Sèvres General Council decided to grant a bonus of 25 centimes of francs for every asp viper killed, with its skin being taken as proof. Despite its elusive nature, the temptation of cash was enough to motivate people, and 7000 asp vipers were killed over the next 6 months alone. Between 1883 and 1900, Henri Gelin estimated that 60,000 were killed in the Deux-Sèvres region, followed by 6,774 in 1905, which amounted to a healthy reward of 1,374.80 francs.
Those are only the years where figures are readily available. Asp vipers aren’t at imminent risk of extinction, and are rated as “least concern” by IUCN, but they’re at huge risk from their favourite habitat being cut down: thick hedges.
| 8 | Their habitat is being shredded |
In 2011 and 2012, scientists embarked upon an epic study of bocages, a wilder than average agricultural field filled with tall grass and bordered by thick hedges. They analysed 142 individual snake habitats, and conducted eight 300 hour recording sessions for each one.
Of the 8 snake species they were searching for, the asp viper was only spotted 64 times. This was spread between 15 of the 142 bocage fields. The figure wasn’t horrendously low, but the study was already focussing on the best possible habitat. Since the 1960s, 40-80% of French asp viper groves have disappeared or been seriously damaged, with 1.4 million kilometres of hedges being cut down. It’s believed that the species benefitted from agriculture until about 1950, when modern practises became too intensive and the balance tipped.
Consequently, the asp viper is a more endangered species than most. But in February 2021, a light shone through, as the French government finally granted the asp viper protected status along with the common European adder. This applied not just to the snake, but to its bocage and bushy hedge habitats.
| 9 | Dunes of demise |
In July 2021, there was a minor media splash when a man from Rigny-sur-Arroux found a red coloured asp viper slithering around his garden. It was at least 70cm, and he smartly scooped up the snake from a safe distance. Coincidentally, the man had been a boa breeder in previous years, and had a handy metal hook standing by. He knew that asp vipers were endangered and never entertained any thoughts of killing it.
Earlier in the year, a dog was bitten on the sandy dunes of Bréville-sur-Mer, located near the English channel. The snake shouldn’t have been there in the first place, as the population was introduced artificially in the 1980s by a reptile enthusiast, but because asp vipers aren’t particularly adventurous, the snakes remained stuck in the dunes, where they survived well. Sadly, the dog later died in hospital, and in April 2020, a woman was bitten on the foot by an asp viper in the same dunes, closer to the town of Pirou. Lesson of the day: don’t go near the asp viper dunes.
| 10 | 5 subspecies across Europe |
Vipera aspis aspis – the main subspecies, and the dominant one in France (including the secret neurotoxic enclave). Also found in northwest Switzerland and Germany’s extreme southwest.
Vipera aspis astra – the alpine subspecies, including most of Switzerland and Italy’s far north. This version has larger dark bars, which sometimes connect to form rings. Melanistic (fully black) snakes are particularly common with this subspecies.
Vipera aspis francisciredi – the main Italian version, living as far south as Naples. Has a significantly wider head, but thinner and more widely spaced dark bars (dorsal bars).
Vipera aspis hugyi – far southern Italy, including Sicily. This subspecies has circular dark dorsal marks instead of bar shaped. The island of Montecristo had a “subspecies” called v.a.montechristi which was proven by genetics to simply be v.a. aspis; it’s believed that they were introduced from Sicily between 900 and 300BC.
Vipera aspis zinnikeri – the Pyrenees subspecies. This mountainous asp viper is so different that some biologists consider it to be a separate species. Its nose is much less upturned, and the dark dorsal bars barely exist.
| !! | Bonus: gets too greedy sometimes |
Failed feeding attempts are everywhere with snakes. Brown watersnakes commonly die after catfish spines pierce their bodies, or sometimes survive and bear the spines for years. In October 2019, an asp viper paid the ultimate price after swallowing a western green lizard. This species lives in western Europe, including a chunk of France, and has a brightly green and blue body you’d expect from Thailand.
The asp viper was already diverging from its trusted mammal food supply, and things got worse. Researchers noticed the viper in Calabria, southern Italy, which was moving normally yet had part of its prey protruding from a brutal laceration in its belly.
The researchers picked up the viper to see if they could provide medical assistance, but over the next minutes, the lizard completely burst out of the hole. It measured 15cm, weighing 17.5 grams. The asp viper measured 33cm and weighed 14g, making it lighter than its prey, with an overall predator to prey weight ratio of 1.25. No wonder it burst out of its body. Miraculously, the asp viper survived this. It slithered into the bushes, and its eventual fate was unknown.