The secretive adders who call Gloucestershire home

Gloucestershire is home to a range of wildlife and threatened species from large blue butterflies and water voles, to pine martens and curlews. One endangered species that calls this county home is the UK’s only venomous snake, the adder.

In woodland glades and on heathlands, adders are sometimes seen basking in sunshine, before slithering away into the undergrowth to hide.

These secretive snakes can live for up to fifteen years, and are relatively small and stocky, with a length of 60-80cm and a weight of 50-100g. They are greyish in colour and have a dark and distinct zig-zag pattern down their backs. Like our fingerprints, they have markings on their heads, which can be used to tell individuals apart.

the front part of an adder, with its tongue out — © Vaughn Matthews

Seasonal snakes

These snakes spend the coldest part of the year hibernating in sheltered places, from about October to the start of March. After emerging in early March, adders need to bask in warm spots to build up their energy, particularly male adders as this is essential for them to mate.

an adders head poking out of a hole in a log — © Margaret Holland

In spring, male adders fend off competition and perform a ‘dance’, females will then mate with the best and strongest ‘dancers’ who are ahead of the competition. Other reptiles lay eggs which will be incubated and hatch outside of the body, but female adders incubate eggs internally, before ‘giving birth’ to between three and twenty live young towards the end of summer.

Adders in danger

Too many disturbances to adders, especially when they are building up their strength in the sun, can be a threat to this endangered species. Needing to move and hide too often uses energy that could be used to catch food that day. Unfortunately, disturbance and a lack of proper protection have led to the decline of adders across the UK.

Now, adders are protected in the UK, but still face threats from habitat loss, disturbance, fragmentation, and predation. Gloucestershire is one of few remaining strongholds for adders, and our neighbouring counties have already lost this amazing species, making it especially important to protect these remaining adders.

Adders are shy snakes and would rather hide than confront and bite humans and domestic animals. Instead, they use their venom to immobilise and kill prey, including small mammals, nestlings and lizards. Adder venom is generally of little danger to humans, but it can be painful and cause inflammation, and can be dangerous to the very young, ill or old.

What you can do

Most bites happen when adders are trodden on or picked up. To help protect this endangered species, and prevent an accident, please avoid disturbing them and keep your dog on a lead. If you or your dog are bitten by a snake, please seek medical attention immediately.

If you spot an adder - or any other species - you can report your sighting to the Gloucestershire Centre for Environmental Records (GCER). This will add to the growing database of information about wild plants, animals and habitats in Gloucestershire, underpinning the evidence which Gloucestershire Wildlife Trust needs in order to prioritise and carry out its important conservation work.

By stopping and reversing wildlife declines in Gloucestershire before 2030, we hope to help this stronghold for adders, as well as the other endangered species that call this county home. By supporting our work or getting involved, you can contribute to safeguarding Gloucestershire’s vulnerable wildlife and wild places.