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Adders thriving – In North Yorkshire

03/04/2009 10:36:59

Adder photo by Silviu Petrovan, Hull University, in Harwood Dale, North Yorkshire.

A South African student who grew up in an area inhabited by deadly cobras is doing his bit to help the rather less fearsome snakes of the North York Moors.

March 2009. Damian Smith, 38, an ecology undergraduate at Hull University's Scarborough campus, is working with the Forestry Commission to amass new data on a colony of adders in 747 hectare (1,850-acre) Harwood Dale, near Scarborough.

The reptile is the UK's only venomous snake, but its shy and elusive nature means it steers well clear of humans. But fears about its future have seen it recently added to the priority species list in the UK Biodiversity Action Plan.

North Yorkshire woods - Adder stronghold
Despite this the Forestry Commission's woods in North Yorkshire remain an adder stronghold and experts are now seeking more information to help them improve the snake's prospects. But studying the adder is a tough job.

"Generally, adders will slither off long before they are encountered by humans," said Damian. "When I was working in Harwood Dale I regularly came across dog walkers who were adamant there were no snakes in the wood - little did they realise there were a couple just a few yards away!"

Damian and one of the adders he studied. Photo by Silviu Petrovan, Hull University, in Harwood Dale, North Yorkshire.

Damian and one of the adders he studied. Photo by Silviu Petrovan, Hull University, in Harwood Dale, North Yorkshire.

75 adders
Damian made 40 visits to Harwood Dale and in total catalogued 75 adders, recording their sex, length, behaviour, the kind of ground they were laying on and the type of nearby vegetation.

Working with Hull University tutor, Dr Phil Wheeler in the Centre for Environmental and Marine Science, the research relied on random survey techniques to eliminate counting the same animal twice.

Adders prefer newly planted trees
One of the key aims was to discover why snakes preferred some areas over others. Damian found that adders like recently replanted areas, where young trees provide shelter from predators like birds of prey, while also offering a good habitat to find prey like mice and voles. The sun is also able to penetrate to the forest floor, enabling the cold blooded reptile to bask and stay warm. However, when the trees grow too tall, they block out much of the sun light, meaning snakes have to move to a better area.

"This is just the kind of data we need to help us manage our forests," explained Brian Walker, Forestry Commission Wildlife Officer. "Actively managing the forest through a cycle of felling and replanting is crucial to the adder's survival. The snake plays a part in maintaining a healthy eco-system, but there's no set way of assessing populations, which makes this new research so important. We now want to work with Hull University to take the research onto the next level."

About Adders

Adders have the most highly developed venom injecting mechanism of all snakes, but they are not aggressive animals. No one has died from an adder bite in Britain for over 20 years. Treat adders with respect and leave them alone.
Most adders are marked with a dark zigzag running down the length of the spine and an inverted 'V' shape on the neck. Females can grow up to 75cms long. Their lifespan is uncertain, but it may be up to 20 years. They go for long periods between meals - adults may eat the equivalent of only nine voles each year.

Adder bites
Before Damian embarked on the project, which forms his dissertation for a BSc Degree in Ecology, he admits to "not being overly fond of snakes." He added:

"My opinion changed when I realised what amazing animals they are. I also became pretty good at spotting them. They tend to pick up on movement, rather than colour, so the key thing is to stay as still as possible when you are near an adder. They are also quite sluggish in the spring when they emerge from hibernation, giving you a better chance of studying them. Although an adder's bite is rarely more than just painful - it has been likened to the sting of a wasp - I took no chances and wore gaiters and thick boots."

Damian grew up in Cape Town and before coming to the UK taught in Thailand. Whilst there he fell in love with the jungle, sparking an interest in ecology and wildlife. That led him to sign up for the Hull University course, where he is now in his final year. He said:

"When we had the recent snowfall I was left thinking about the poor snakes in their hibernation boltholes in Harwood Dale having to endure freezing weather. I just hope the guys I studied make it through to the spring."

Another adder. Photo by Silviu Petrovan, Hull University, in Harwood Dale, North Yorkshire.

Another adder. Photo by Silviu Petrovan, Hull University, in Harwood Dale, North Yorkshire.

Best time to see adders
The best time to see them is in early spring. When the days warm, there is a lot of frenzied activity, with males looking for females and wrestling with other males for supremacy. Unlike most reptiles, adders do not lay eggs. Young snakes are born about the size and shape of an earthworm, but a perfect miniature of the adult snake. During the autumn adders go into hibernation. Their survival largely depends on the severity of the winter weather. Adders are protected by law against being killed or injured through human activity. For more go to

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