Notes on...

Is the adder slithering towards extinction?

3 April 2021

9:00 AM

3 April 2021

9:00 AM

In early April, when the chiffchaff sings its drab little song in the leafless hawthorns, something is stirring in the dead bracken. Having spent the winter months underground, one of our most fascinating creatures slithers into the weak spring sunshine: the adder.

The emerging adders haven’t eaten for six months, but food is not on their minds; it is the mating season. Rival males indulge in spectacular ritual combat, rearing up side by side and twisting and wrestling at great speed. After mating the snakes disperse and spend the summer in solitary pursuit of mice, voles, lizards, frogs and fledglings.

Adders never use more energy than is necessary and spend a lot of their time basking. These living solar panels get a great deal of their energy directly from the sun, and so efficient is their metabolism that they only require six to ten meals a year. The adder should be the symbol of green power.


Most snakes live in climates that are hot enough to incubate their eggs. The adder insures against our northern summer by basking at every opportunity and incubating the developing embryos inside her body, eventually giving birth to between six and 20 live young in August or September. This adaptation has allowed the adder to range further north than any other reptile.

The young adders are dark brick-red, except for the end of the tail which is lime yellow. This pale tail tip can be wriggled like a little maggot to entice froglets and baby lizards. This ruse, known as ‘caudal luring’, is found in many snakes, and reaches its pinnacle in the astonishing spider-tailed horned viper, which lures birds into striking distance with the spider-like appendage on its tail tip.

Adders are surprisingly vulnerable and are preyed upon by buzzards, ravens, crows, gulls, herons, pheasants, badgers and hedgehogs. The worm-sized young are not even safe from blackbirds. Domestic cats have no hesitation in attacking snakes as endless YouTube footage will testify.

Not many people would kill an adder on sight these days, but there is still a threat from human activity. Disturbance and loss of habitat has caused the adder to disappear from many places where it was once common. Our network of roads, motorways and developed areas has resulted in many adder populations becoming isolated, leading to inbreeding and congenital weakness. In the past decade, the adder population has declined by more than half and at this rate they could be extinct in Britain in 20 years.

Humans have a primal and deep-rooted mistrust of snakes. From Genesis to Harry Potter, they’ve had a bad press. Adders are no exception. Our literature and folklore are crawling with negative references to them. Chaucer called them ‘sly untrewe’ and in Geoffrey of Monmouth’s Arthurian legends Merlin foretells that the ‘adder of Lincoln’ will summon dragons with its hiss.

Now, at last, we are treating this much-maligned snake with sympathy, and naturalists are doing their best to halt its decline. Let’s hope that our children’s children can still experience the thrilling sight of a coiled adder in the April sunshine.

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