If you’re visiting Anglesey during the warmer months, you may be lucky enough to spot some of the island’s amazing wildlife. But there’s one creature you’d rather admire from afar – the adder.
These native snakes are shy and generally avoid humans and dogs, but during Spring and Summer, they may be out basking on heathland, sand dunes or near the coastal paths. A startled adder may bite in self-defence – so here’s how to avoid that happening, and what to do if it does.
The truth about “Adder Season”
There’s a common myth that you should avoid walking dogs in hot weather to avoid adders. But the truth is: cool adders are the ones to watch out for.
- Warm adders are alert and quick to flee at the sound of footsteps.
- Cool adders are sluggish and more likely to be caught off guard – which is when they’re more likely to bite.
So ironically, walking on cooler days (especially in Spring or early mornings) can actually increase your chances of encountering one.
When are Adders active?
Adders are most likely to be out and basking when the temperature is between 10°C and 17°C.
- Below 10°C: They stay hidden underground.
- Above 17°C: They’re more active and harder to spot — which actually makes them easier to avoid.
Your safest walking times? When it’s colder, much hotter, raining, or after dark.
Where on Anglesey might you see adders?
Typical adder habitats include:
- Coastal paths
- Heathlands
- Coastal dunes
- Wild grassy areas
If you’re heading out near coastal path stretches or the gorse-covered inland trails, especially around early Spring or late Autumn, just stay alert and keep your dog on the path.
At Gwendon Holiday Home, most of our guests never spot one – and that’s exactly how the adders like it. They avoid humans when they can.
What time of day is safest for dog walks?
In Spring and Autumn, adders usually bask between:
- 9am to 11am
- 3pm to 7pm
They’re most likely to bite dogs between April and July, especially in the late afternoon – around 3pm to 4pm. To reduce the chances of crossing paths, aim for walks before 9am or after 7pm.
In Summer, they can be active earlier and later into the day – so if it’s been a warm day, consider walking early morning or after sunset.
Cloudy or hazy sunshine and sunny spells between showers can bring them out at any time, so it’s always smart to stay cautious.
Adder bite symptoms
Adder bites can be serious, but they’re rarely fatal – if treated quickly. Immediately check for two small puncture wounds, swelling, or redness in the area – these are common signs of an adder bite.
If you don’t see the incident or notice any immediate distress from your dog, you may spot the following symptoms later on:
- Severe swelling around the site of the wound
- Visible pain, such as limping or holding up a leg
- Bleeding or bruising
- Inflammation from the spread of venom
- Increased heart rate or quickened breathing
- Drooling
- Vomiting
- Lethargy or general weakness
What to do if your dog is bitten
If you suspect a bite
- Don’t panic. Staying calm will not only help you, but it will help your dog stay calm as well.
- Carry your dog if you can, or keep them as still and calm as possible. Have the bitten area elevated above the heart if possible. Keep your dog warm.
- Bathe the wound in cold water or saline pod and use an ice pack to help control the swelling. Don’t attempt any first aid such as squeezing the wound, as this can do more harm than good.
- Get to a vet immediately. Call them beforehand to get immediate advice.
Movement spreads venom more quickly, so the less your dog moves, the better. A Snake Bite Kit such as this (supplied at Gwendon) can provide temporary relief while you arrange a vet visit.
Adder bites can be scary, but the good news is they’re rarely fatal for dogs. How serious the bite is depends on things like how much venom was injected, where your dog was bitten, and your dog’s size and overall health. Smaller pups or those with existing health issues might be more vulnerable to a stronger reaction.
That said, most dogs make a full recovery – especially when they get the right treatment quickly. So if you think your dog’s been bitten, don’t wait – get them to the vet straight away.
How vets treat adder bites
Pain relief
Adder bites can be really painful, so one of the first things a vet will usually do is give your dog something to help with the pain and keep them comfortable.
Anti-inflammatories
To help bring down swelling and ease inflammation around the bite, your vet may give anti-inflammatory medication.
Fluids
If your dog is showing signs of shock or a more serious reaction, they might be put on a drip. Fluids help keep their blood pressure steady, support their organs, and prevent dehydration.
Antivenom
In more severe cases, your vet may use antivenom – but only if it’s absolutely necessary and they have access to it. It’s not always needed, and vets are careful with it because there’s a small risk of an allergic reaction. Whether it’s used will depend on how strongly your dog is reacting to the bite.
How to spot a adder
Adders – also known as European vipers – have some standout features that make them easier to recognise, if you know what to look for:
Colour and pattern
One of the easiest giveaways is the bold zig-zag pattern running down their back. This can range in colour from deep brown to jet black. The rest of their body might be grey, reddish, or even have a greenish tint, depending on the individual.
Size
They’re not massive. Most adult adders measure around 60–80cm long – roughly the size of a guitar. Males are generally slimmer and a bit smaller than females.
Head shape
Look for a ‘V’ or arrow-shaped marking on the top of the head. Their head is slightly triangular – kind of kite-shaped – which is a classic trait of many venomous snakes and helps tell them apart from harmless UK species.
Eyes
If you ever get close enough (which we wouldn’t recommend!), you’ll notice their reddish eyes with vertical, cat-like pupils. It gives them a slightly eerie stare.
Quick tips for dog safety on Anglesey
- Keep your dog on a lead in overgrown or wild areas.
- Avoid walking during adder basking hours (10–17°C window).
- Stick to clear, open paths.
- Don’t let your dog sniff around in long grass or under bushes.
- Carry your dog if bitten and head straight to the vet.
Helping wildlife while protecting your pup
Adders are a protected species here in the UK – and despite their bad reputation, they play an important role in the ecosystem and are more afraid of us than we are of them.
By giving them space and staying aware, you’re helping your dog and supporting Anglesey’s wonderful wildlife. So if you spot one while out walking, enjoy the moment from a safe distance and let it be.
If you’re unsure about where to walk safely during your stay, just stick to the main paths and keep your pooch on a close lead.
Have you ran into an adder?
Have you come into contact with adders on your travels? We’re interested to hear your story!