Where do adders live?

Adders are found throughout much of England, Scotland and Wales (but absent from Northern Ireland and the Republic of Ireland), and throughout most of Europe. They are the most northerly found snake with a distribution into the Arctic Circle. It may be argued that across the wider landscape that they have the largest distribution of any snake being found from the north-west corner of France all the way through to the Far East including north-east China.

Adders can be found in a large number of habitats such as heathland, open woodland, chalky downs, rocky hillsides, moors, meadows, coastal dunes, and stone quarries.

How do adders survive in the Arctic?

Adders, perhaps more than any other snake, blur the traditional boundaries between cold- and warm-bloodedness. They are the only snake found within the Arctic Circle, specifically Scandinavia and Russia.

The most obvious adaptation for life so far north is evident in early spring, when basking adders appear almost to stretch out each of their ribs and flatten their bodies like pancakes. By doing this, they increase the surface area in contact with the sun’s rays, turning them into efficient reptilian solar panels.

Northern adders are also helped by their reproductive strategy. Whereas many snakes lay eggs in naturally warm spots, such as compost heaps, adders retain the developing embryos in their bodies and ‘give birth’ to live young. The babies are therefore insulated from the extremely cold temperatures that eggs laid outside probably couldn’t withstand.

There’s also their diet. Small mammals thrive in the northern springtime. One successful strike with its venomous fangs and an adder can live happily for weeks – even months – through any late cold snaps.

This Q&A originally appeared in BBC Wildlife, and was answered by Jules Howard.

What do adders eat?

The diet of the adder can be varied depending on what habitat they are found in. In most, the diet consists mainly of small mammals such as voles and mice, however larger animals may even take rats. Other reptiles such as lizards and slow worms are often on the menu too.

The diet of adders not only depends on the location, but the size of the snake too. Generally speaking larger animals will take larger prey but this also gives them the ability to reach food sources that smaller snakes may not be able to including nestling birds and eggs.

On rare occasions adders have been recorded to each amphibians such as frogs and newts. As an opportunist, they will eat whatever comes their way although once they reach roughly half their adult size, the diet of younger snakes resembles that much more of larger and more mature adults.

---

Does the adder’s tongue only detect prey?

For small mammals, the sight of a hungry adder flicking its forked tongue is the stuff of nightmares. But adders, like many other snakes, use their tongues for finding sex as well as dealing death.

In spring, a male adder locates a female by homing in on the scent trails she leaves behind as she moves, and he may travel many hundreds
of metres in a single day, excitedly licking the air as he moves. By flicking out his tongue, he mops up from the air molecules of female scent (pheromones) that are then carried by the tongue to the Jacobsen’s (or vomeronasal) organ at the back of the mouth. These molecules excite special receptor cells by which the snake registers the smell.

If more pheromone molecules are detected by one prong of his forked tongue, the male changes its direction until the scent arrives in equal quantities at both prongs.

Far from being something sinister, the adder’s tongue is a feature that has probably been shaped during evolution by sex as much as by death.

This Q&A originally appeared in BBC Wildlife, and was answered by Jules Howard.

---

What eats adders?

The flipside of the coin, what does eat adders? Surprisingly, adders are mainly predated on by birds such as corvids, birds of prey (like the buzzard) and pheasants. The smooth snake feeds primarily on other reptiles and so adders are sometimes on the menu. Other predators include mammals such as badgers, foxes and feral cats.

---

Are adders venomous, and are adder bites fatal?

Adders are infamous for being the only venomous snake found in the UK. This often creates a sense of fear and animosity surrounding them, which is completely misplaced. Adders are much likely to flee from a fight than envenomate a person, due to the expensive metabolic cost of producing the venom. They’re extremely unlikely to attack people just for the sake of it.

In those that are unfortunate enough to be bitten, these tend to occur on the feet and ankles where snakes have accidentally been disturbed as people are walking through a habitat and stood on a snake. This can also happen to dogs that are off the lead in areas where adders are to know to occur.

In both cases the fatality rate due to adder bites is low with the last death in the UK recorded in 1975. The young and old are at particular risk but as long as medical treatment is sought immediately after an envenomation (both human and canine), then the damage caused can be minimalised.

In most cases the bites cause no more pain or damage than a bee or wasp sting, however some people can have an allergic reaction. The same can’t be said for their prey, that often succumbs to the venom fairly quickly due to their much smaller body size.

---

How do adders deliver the venom?

Like other vipers, adders have hollow fangs that they use to deliver their venom deep into tissues and blood vessels where it can set to work. These are connected to their venom glands which help to deliver venom when the snake attacks prey.

Without any limbs to help immobilise it and being too stocky to effectively constrict their prey, vipers have opted for chemical warfare instead. There is evidence to suggest that venom in snakes evolved from saliva and has been acted upon by natural selection since to produce the wide variety we now see today.

---

Do adders have any non-venomous mimics?

Yes. In southern Europe the non-venomous viperine water snake (pictured above), a close relative of the grass snake, mimics not only the adder’s markings but also its hiss and behaviour: when threatened it adopts an adder-like posture and launches dummy strikes at attackers.

It is also likely that the dark markings of smooth snakes mimic an adder’s chevrons. Indeed, the decline of a population of smooth snakes on a Finnish island has been linked to the local extinction of adders – with no venomous lookalikes around, predators lost their fear of the markings.

This Q&A originally appeared in BBC Wildlife, and was answered by Stuart Blackman.

---

Do adders hibernate?

Yes, adders like all of our native reptiles hibernate between around October and March. During this time, they congregate in areas known as hibernacula which act as a frost-free refuge until the following spring.

This means that inadvertent damage to a large hibernaculum, can be catastrophic for a small population especially if they are isolated from others.

---

When do adders breed and what is the adder dance?

Following hibernation, males are the first to emerge. It is crucial that males bask in the sun if they want to successfully breed that year. They spend up to two months basking in order to maintain their metabolism so that they can start to produce sperm after the winter slumber. Females will then emerge in late April-May with reproduction on their agenda, by which time the males should be ready.

Please note that external videos may contain ads: