Experts to perform health check on England's only venomous snake.

News release from Natural England.

Adder concerns

Snake experts from Natural England, Zoological Society of London {ZSL} and Oxford University have teamed up to perform a vital health on Britain's only venomous snake, the adder, following worrying declines.

With its iconic zig-zag markings, the adder was once a common sight in large parts of the British countryside. But in the last decade it has slipped into decline, with surveys suggesting a third of remaining adder populations may comprise fewer than ten adults.

Scientists believe this is down to the disappearance, degradation  and fragmentation of habitat, resulting in smaller more isolated populations of this enigmatic reptile.

It is feared that if these smaller populations, particularly in the English Midlands are not able to maintain a healthy level  of genetic diversity , their resilience to disease will be reduced and a concentration of genetic defects could occur, leading to local extinctions.

For the first time a team of experts a team of snake experts are heading into the under growth to obtain genetic samples from the adders. This simple, harmless test involves taking a DNA swab, which can be used to determine current levels of genetic diversity.

Whilst the scientific procedure is risk free for the snakes, the experts will be taking every safety precaution necessary to avoid being bitten-this is not something that should be tried at home.

Dr Trent Garner, Senior Research Fellow at ZSL's Institute of Zoology said " Genetic diversity has been shown to be the key component for successful adder population in Sweden and Hungary, but has yet to be studied in the U.K., our goal is to provide the first insights into how population size and isolation may be related to genetic diversity of U.K's adders"

Jim Foster, reptile specialist for Natural England said " With around a third of adder populations now restricted to isolated pockets of habitat, and with only a handful of snakes per site, they could be especially vulnerable. As we have seen with natterjack toads, populations that are small and isolated can start to decline purely through genetic effects. This ground breaking study will see if adders are suffering a similar plight.

"Fortunately, if there are problems we still have time to deploy a number of conservation remedies. Habitat restoration and the creation of wild life corridors will help get these snakes back on the move. We may even consider moving adders between populations, to artificially promote "gene flow"-although that carries risks and we would need to look more closely at the genetic results before proceeding"




Dr Tobias Uller of Oxford University's Department of Zoology said " When populations become small and isolated, with it comes the risk of expression of harmful genetic variants that normally remain "hidden" in larger populations. Loss of genetic variation may also compromise the populations ability to evolve-a problem that is particularly acute when habitats change rapidly or if a new disease emerges"

Adder and conservation

 The adder, Vipera berus is one of three snakes in England { the others are the grass snake and smooth snake}. The last national analysis showed worrying trends toward the isolation of populations, with declines in adder numbers recorded at around a quarter of the sites, and more local extinctions among adders than other reptiles. A survey published by the Amphibian and Reptile Conservation earlier this month found adders to be present in only 7% of surveys nationally. 

The adder is listed as a national priority species in the U.K. Biodiversity Action Plan. 


Natural England is the Government's independent adviser  on the natural environment. Established in 2006 { Formerly English Nature} their work is focused on enhancing England's wildlife and landscapes and maxamising the benefits they bring the public.


December 2011

ADDER MOST THREATENED SPECIES---- According to Froglife news--- here in the UK, experts in the South East of England have just declared that the adder is in more urgent need of new conservation efforts than any other  reptile or amphibian species in Britain. 

At a recent conference, delegates heard about the drastic loss of habitat and resulting isolation and inbreeding that are all contributing to declines.