Vanishing adders put at risk of extinction

A nationwide survey of amphibians and reptiles found that numbers of the snake, once thought to have been relatively widespread, have suffered an alarming decline.

Out of some scores of areas surveyed by the Amphibian and Reptile Conservation Trust, adders were discovered in just 5 per cent, a finding experts admitted was "shocking".

Dr John Wilkinson, the trust's research and monitoring officer, told The Scotsman that the paucity of the sightings meant it was "not unreasonable" to presume that adders were on the verge of being wiped out altogether in parts of the country.

However, Scottish Natural Heritage (SNH), urged caution, pointing out that the surveys - carried out by volunteers - had not covered every part of the country.

The trust has been gathering data on the subject for the past four years, and has published the interim findings of its National Amphibian and Reptile Recording Scheme (NARRS), which cover the first half of the six-year survey period from 2007 to 2012.

While it looks at the populations of a range of species it is the figures relating to adders - Vipera berus - which make for the most alarming reading. Out of 56 areas surveyed in Scotland, just three - one site in Easter Ross and two near Lockerbie - were found to be home to adders, accounting for a species occupancy rate of just 5 per cent.

The same percentage was reported in northern England, while central England and Wales had the highest rate (12 per cent). Across the UK, the average was 7 per cent.

Dr Wilkinson said: "The 5 per cent figure is shocking, and it's the same pattern we're seeing across the UK. Even though there are more surveys being carried out, and we have a good group of volunteers in Scotland, no adders are being found.

"In the past, the good places for adder distribution in Scotland were in Grampian, the Highlands, the Mull of Kintyre area, central western Scotland, and also the Borders.

"But it's at a dangerous low level. In some areas where we're not finding adders at all, they may have gone completely. We can't say that with 100 per cent certainty, but it's not unreasonable to say adders are in danger of becoming extinct in those areas."

Dr Wilkinson said the decline could be attributed to agricultural intensification and the increasing development of once rural areas, although he did "not rule out" the effects of climate change as a factor.John McKinnell, SNH'S policy and advice officer for reptiles, said: "This survey is designed to give a picture across the whole UK but depends on volunteers and does not yet cover the whole of Scotland, for example the west and central Highlands were not surveyed, so it is not possible to accurately say whether adders are declining. We suspect they are, but probably not as dramatically as this survey would seem to show."

SNAKE BITES

The adder - Vipera berus - is Britain's only venomous snake. They have a dark zig-zag on their backs, against a pale brown or grey background. Females can be distinguished by their greater length, duller colouring and orange eyes.

Its preferred habitat is heather moorland, especially with dry stone walls. They are also found on the borders of woods and fields, overgrown quarries, and railway embankments.

Relatively thick-bodied, adults grow to 60cm in length.

Mid-April is the snake's mating season and heralds the "dance of the adders", with mating males wrestling each other for supremacy.

Although they are the UK's most venomous species, a bite from an adder is rarely fatal, and during the past 70 years there have only been seven deaths from this cause. The effects are usually shock, anxiety or even panic. The victim must be kept calm and medical advice sought as soon as possible.

It is illegal to kill, injure, harm, or sell adders under the 1981 Wildlife and Countryside Act.