adder

What our animals are doing this month…

September 1, 2025 by Admin

September: A Key Month for the Adder

As summer draws to a close, September marks a turning point for one of the UK’s most fascinating native reptiles, the adder (Vipera berus). This month brings a shift in their behaviour, with individuals beginning the journey back to their overwintering sites, where they’ll eventually spend the colder months in hibernation.

Heading Home for Winter

From September onwards, adders start moving towards their overwintering locations, places they often return to year after year. These hibernation spots, known as hibernacula, are usually sunny, south-facing embankments that provide shelter from frosts, rain, and predators. Common examples include old mammal burrows, hollow tree stumps, root systems, tussocks, rockeries, and even piles of dead wood.

Once near these sites, the snakes can still be spotted basking in the sun well into late October, only retreating fully when the weather makes it necessary.

September: Prime Adder-Spotting Season

For wildlife enthusiasts, early autumn can be a fantastic time to see adders in the wild. As the days cool, they tend to spend more time basking in open areas during sunny spells. This behaviour helps them regulate their body temperature before the long winter ahead.

Adders are relatively easy to identify thanks to their distinctive features: a bold dark zig-zag pattern along their back, a red iris with a vertical pupil, and an average length of 60–80cm.

Sun-Lovers with a Safety Plan

Even as temperatures drop, adders will bask in surprisingly cool weather, provided the sun is shining. However, they’re careful about where they choose to do it. Ideal basking spots offer both warmth and safety, with sunny exposure and long vegetation nearby, often about the length of the snake’s own body, providing quick cover if a predator passes by.

A Seasonal Spectacle

September’s combination of cooler temperatures and bursts of autumn sunshine makes it one of the best times to appreciate this often-misunderstood reptile. Whether you’re a seasoned wildlife watcher or just enjoy a walk in nature, keeping an eye out for the adder can be a rewarding experience, just remember to observe from a respectful distance, for both your safety and theirs.

And don’t forget, if you spot any reptiles, amphibians, or even their eggs, make sure to record your sightings on our FREE Dragon Finder App.

Your observations help us track populations and protect the habitats of these wonderful wild creatures.

UK Reptile ID

April 1, 2025 by Admin

Written by Paul Arestides, Transforming Lives Trainee

The UK is home to six native species of reptile – three snakes (adder, grass snake and smooth snake) and three lizards (common lizard/ viviparous lizard, sand lizard and slow worm).

In early spring, snakes and lizards will start to emerge from brumation – if you are lucky you may see one or more in your garden or when out walking in the countryside.

All three species of snake in the UK reproduce by laying eggs. The adder and smooth snake incubate eggs internally and then ‘give birth’ to live young. The grass snake lays eggs externally in rotting vegetation, for example, compost heaps.

Take a look below for some more fascinating facts about the UK’s native reptiles.

Grass snake (Natrix helvetica)

Size: 90-150cm in length (females tend to be the longest)

Colour: Usually greenish in colour, with a yellow and black collar, pale belly and dark markings down the sides.

Habitat: Favours wetland habitats but can also be found in grassland and gardens, especially those with a pond!

Interesting fact: The grass snake is the longest snake found in the UK.

Adder (Vipera berus)

Size: 60-80cm in length. Very stocky.

Colour: Grey (males)/ brown (females) with a dark and very distinctive zig-zag pattern down its back. Red eyes.

Habitat: Prefers woodland, heathland and moorland but may also be found in grassland or on the coast.

Interesting fact: The adder is the only venomous snake in the UK. However, bites are exceptionally rare as adders are reclusive and would prefer to retreat than confront a human. The last recorded death from an adder bite in the UK was in 1975.

Smooth snake (Coronella austriaca)

Size: 50-70cm in length.

Colour: Usually dark grey or brown in colour. Similar to an adder but with a more slender body and without the zig-zag pattern along its back.

Habitat: Very rare. Mainly found on a few sandy heaths in Dorset, Hampshire and Surrey, although a couple of reintroduced populations exist in West Sussex and Devon.

Interesting fact: The smooth snake is a constrictor, coiling around its prey to subdue it and crush it to death

Most lizards have four legs and run with a side-to-side motion. However, some, such as the slow worm, are legless. Lizards are mainly carnivorous and often employ a ‘sit-and-wait’ approach to catching prey. In the UK, lizards feed primarily on insects, molluscs and spiders.

Sand lizard (Lacerta agilis)

Size: Up to 20cm.

Colour: Female sand lizards are a sandy-brown colour, with rows of dark blotches along the back. Males have green flanks that are at their brightest during the breeding season, making them easy to spot.

Habitat: The sand lizard is very rare and can only be found on a few sandy heaths in Dorset, Hampshire and Surrey with a few reintroduced populations in the south east, south west and Wales.

Interesting fact: Sand lizards dig burrows for overnight refuge and hibernation.

Slow worm (Anguis fragilis)

Size: 40-50cm.

Colour: Smooth, golden-grey skin. The males are paler in colour and occasionally have blue spots. The females tend to be larger with dark sides and some have a dark line down their back.

Habitat: Slow worms live in most of Great Britain apart from Northern Ireland and are also present on most of the islands in Scotland and the Channel Isles.

Interesting fact: Although similar in appearance to a snake, the slow worm has eyelids (which snakes do not) and can drop its tail when threatened by a predator.

Viviparous/ common lizard (Zootoca vivipara)

Size: 10-15cm in length.

Colour: Variable, but most commonly a brownish-grey, with rows of darker spots or stripes down the back and sides. Males have bright yellow or orange undersides with spots, while females have paler, plain bellies.

Habitat: Heathland, moorland and grassland.

Interesting fact: If threatened by a predator, the common lizard will shed its tail which continues to move – the lizard uses this distraction to make its escape. Although able to regrow its tail, the new one is usually shorter than the original.

Help us by becoming a citizen scientist! Reptiles are widely under-reported and we want your records to see how well reptiles are faring in the UK. Download our free Dragon Finder App to get started.

What our animals are doing this month…

March 1, 2025 by Admin

Written by Emma Byrne, Transforming Lives Trainee

March is an important month for the UK’s amphibian and reptile species. The general temperature is gradually warming, and as such, many of these species are coming out of hibernation ready to breed, feed, and explore their habitats.

Amphibians:

Frogs, toads, and newts are on the move!

Common frogs and toads migrate in large numbers towards their breeding ponds, with many crossing roads in the process making projects such as Toads on Roads necessary. Male frogs can be heard croaking to attract mates, whilst spawn begins to appear in ponds. Smooth and great crested newts are also heading to the water where they perform spectacular courtship displays!

Reptiles:

The only venomous British snake, the adder, emerges from hibernation as days lengthen. Males have been observed lying out in the sun, a behaviour that allows them to build up energy before shedding skin prior to breeding season. Other reptiles, such as grass snakes and slow worms, also awaken but bide their time waiting for even warmer weather to descend.

March is the perfect month to get outside and begin looking for amphibians and reptiles in the wild! If you happen to see any, please register your sighting on our free Froglife Dragon Finder App.

Year of the snake

February 1, 2025 by Admin

Written by Emma Byrne, Transforming Lives Trainee

2025 is the Year of the Snake according to the Chinese Zodiac. In light of this, let’s look at the three native snake species in the UK.

Adder – The UK’s Only Venomous Snake

The adder is the only venomous snake in the UK. This small, stocky species thrives in woodland, heathland, and moorland habitats. Females incubate their eggs and can give birth to as many as twenty live young! Adders hibernate starting in October and emerge in March to bask in the sun. Adders are easily recognized by their distinctive dark zig-zag pattern and red eyes. Males are more silvery-grey, while females are often lighter or reddish-brown. Although venomous, they are shy and prefer to avoid humans.

Grass Snake – Britain’s Longest Snake

Grass snakes can grow over a meter, making them the longest snake in the UK. They are typically grey or green and feature a yellow and black collar around their neck. As the only egg-laying snake in the UK, they can lay up to forty eggs in sheltered spots such as compost heaps. Grass snakes are commonly found in England and Wales, especially near garden ponds, where they feed on amphibians and fish.

Smooth Snake – A Rare Species

The smooth snake is rare, found only in a few sandy heathland areas in Dorset, Hampshire, and Surrey. This protected species is part of reintroduction programmes, aimed at preventing its extinction in Britain. Smooth snakes are ectothermic, basking in the sun and hibernating from October to April. Males compete for females, who give birth to between four and fifteen live young in September.

Throughout 2024, grass snakes have been spotted at our Boardwalks and Hampton reserves! If you visit one of our public reserves, keep an eye out this spring as they emerge from hibernation to bask in the sun!

Remember to report your sightings on our free Dragon Finder app.

What our animals are doing this month

February 1, 2025 by Admin

Written by Charles Bonnett, Transforming Lives Trainee

It’s February and we’re settling into the New Year. For our animals, February can represent a period of transition, as the first signs of spring start to stir them from their dormancy.

For some amphibians, February marks the beginning of their habitual migration to their breeding ponds. Male common frogs typically arrive first, ready to attract females. In warmer, southernly regions of the country, mating may have already occurred by late February and frogspawn may be present. Likewise, during warm, wet evenings, common toads will begin their migration to their ancestral breeding ponds; these epic journeys can sometimes span kilometres. Some of our three native newt species, smooth, palmate, and great crested newts, will similarly begin to rouse from their dormancy, though will likely remain more inconspicuous than their frog and toad counterparts.

In comparison to amphibians, our reptiles are more temperature-sensitive, and so will mostly maintain their dormant state throughout the cold February days in order conserve their energy. Though, this does not mean that reptiles will be completely inactive during this period; a warm spell may stir adders and common lizards from their inactivity, after which they may be seen basking on south-facing slopes to regulate their body temperature in preparation for spring.

Generally, there is a degree of variation in when a member of a species may exit brumation, in part influenced by regional variation in weather, where earlier activity may be observed in more southerly regions. A further notable impact on this transition is our ever-changing climate. Our winters are becoming milder and less predictable, leading to our amphibians and reptiles exiting their dormant state prematurely. This early emergence can be dangerous, as it can leave the animals exposed to unpredictable weather, such as cold snaps. Likewise, it can cause the expenditure of energy during colder periods which may be difficult to recoup as sources of food will be rarer.

Overall, then, February can be a transitionary period from dormancy to activity for our amphibians and reptiles, and will likely continue to be with greater frequency due to our changing climate.

Remember to report any sightings of our species (including eggs and young) on our free Dragon Finder app.

New Adder genetics study: implications for Conservation

October 2, 2024 by Admin

Written by Jenny Tse-Leon, Head of Conservation & Impact, Froglife

adder A new study published today by ZSL’s Institute of Zoology, the University of Cambridge and Froglife highlights important implications for conservation of translocating adders.

Researchers studying an adder population in eastern England found that a population formed by the release of seven individuals managed to establish a population despite low genetic diversity – although there may have been an additional, unlicenced translocation at a later date. DNA samples found the genetic signature of the translocated snakes in the population, indicating that the translocation has been successful over the long term. However, there was also evidence of reduced genetic diversity, likely due to the small number of animals involved in the translocation.

The study was initiated after the 2015 discovery of a stillborn clutch of five adders still in their amniotic sac, raising the question of inbreeding in the population. Genetics samples of the stillborn clutch were collected as part of the Garden Wildlife Health project, a national wildlife disease surveillance scheme.

Analysis found that the clutch sampled was likely fathered by more than one male. However, the reasons behind stillbirth could still be genetic, as well as environmental maternal effects.

Despite being given some protection by the Wildlife and Countryside Act, adders can still be moved to new sites (translocated) without the need for this to be recorded or monitored – meaning very little is known about its impacts on adders. The population in this study was known to come from the introduction of seven adders from a development site 20km away, eighteen years previously, to a reserve now managed by Froglife. This provided a rare opportunity to study the impacts of a small translocation on the resulting population – making it one of few, long-term genetic based studies following an adder translocation.

Adder populations in the UK are severely declining, particularly small populations, due to habitat loss, habitat fragmentation, human disturbance and consequentially inbreeding as populations become increasingly isolated. While misconceptions about adders have led to their persecution, these snakes are not dangerous if left alone and are an important and culturally relevant part of the UK’s natural heritage.

Professor Trent Garner, researcher as ZSL’s Institute of Zoology said: “Adders are declining in numbers across Western Europe, and we need a better understanding how translocations could be used to reverse these declines and restore their numbers. Population genetics can be used to understand the more long term outcomes of translocations in terms of reproduction and population growth. Careful management and ongoing monitoring are key to ensuring future populations are genetically healthy and able to grow and flourish.”

Since managing the reserve, Froglife has carried out annual reptile surveys showing a supposedly healthy and likely expanding population resulting from this translocation. This study found however that the adder population has a low genetic diversity in comparison with published data from similar sized adder populations which is typical for a bottleneck in the population history. The cause of the stillbirth clutch might have been a result of maternal fitness, which could either be a result of inbreeding or another factor such as disturbance from dog walkers, mountain bikers and trampling of vegetation. Whatever the reason, female adders often have only one litter in their lifetime, so the loss of the whole clutch can have a significant genetic and demographic impact on a population, especially an isolated population with low genetic diversity. In this study the loss of four females in the clutch is significant in a population already showing a relatively low proportions of females. It highlights the need for protection of small populations in particular and ensuring connectivity between different populations.

“The discovery of a clutch of stillborn adders was very worrying however the outcomes of the research are reassuring for this population. The study shows the value of long-term monitoring and the need for ongoing funding to enable this to happen. It would also not have been possible without the support of our committed volunteers.” Jenny Tse-Leon, Head of Conservation and Impact at Froglife.