Enjoying Sand Lizards at Arne

 

Sand Lizards are one of Britain's most spectacular reptiles, and it is always a privilege to get good views of them. One of the advantages of being a reptile surveyor is the opportunity to attend training days to improve survey and identification skills. Today was one such session, held at the RSPB's Arne reserve next to Poole Harbour in Dorset, UK - a site that I know well as a local volunteer. Among its many wildlife attractions, which will be familiar to viewers of past series of BBC's 'Springwatch', the reserve hosts all six of Britain's native reptile species.

The session was led by Gary Powell and Nick Moulton of Amphibian and Reptile Conservation, and was carried out under licence as the Sand Lizard is a protected species. As always, the welfare of the animals comes first.

It is rarely easy to find wild reptiles, especially on very sunny days like today when their activity levels were already high by mid-morning. It is much better to search on cooler and cloudier days when lizards and snakes need longer to warm up before they can start moving around. More basking time means that they should be easier to spot. But you can't guarantee it! 

Even with the many eyes of our group, it took over an hour to locate the first Sand Lizard - the handsome individual pictured at the start of this blog. The green colour shows that he's a breeding male, and we are now well into that season on the Dorset heaths. Sand Lizards have been out of hibernation for a couple of months here (I saw my first of the year back in mid-March). Males emerge a week or so later than females, and their full breeding colour takes a short while to develop. 

A second male this morning, moving through a bundle of dead Gorse, was similarly colourful but less willing to pose for a picture (below).

Sand Lizard (male) - RSPB Arne, Dorset

But what about the females? Unlike Common Lizards, which give birth to live offspring, female Sand Lizards lay their eggs underground, usually one clutch of 4-12 eggs per season. Understandably, the females are quite choosy about where they do it and will dig several (sometimes many) 'test burrows' before deciding that one is suitable to accommodate their future young. 

The presence of these test burrows is a good indication that you have a breeding population of Sand Lizards on site. According to the literature their construction usually takes place in late May. However, we saw a good number on the heathland this morning. Climate change seems to be bringing this activity, and many other natural processes, forward in time.

Two Sand Lizard test burrow entrances - RSPB Arne, Dorset

What makes a successful egg burrow for a female Sand Lizard? Bare ground is favoured, but a balance is needed between soil that is too hard or compacted to excavate and sand that is so loose that the finished burrow will collapse. If rocks or large stones are encountered underground then digging will probably be abandoned. Sunny, south facing sites are preferred, within close proximity to cover such as  deep heather or a gorse bush.

This morning, we were extremely lucky to come across a female Sand Lizard in the process of excavating a burrow (photo below). Only her tail is visible.

Female Sand Lizard digging an egg burrow (tail only visible) - RSPB Arne

The lizard was too busy digging to bother about (or possibly even notice) our presence. We left her to it: will this burrow meet her exacting requirements, I wonder? But when she is finally satisfied, she will emerge from the favoured burrow before reversing back in to lay her eggs. The burrow will then be carefully filled in so that it cannot be detected. Any excavations remaining obviously visible will be discarded test burrows that didn't make the grade.

It will usually take two or three years for Sand Lizards to reach maturity and start breeding. Before that, juvenile lizards will roam the heathland in search of prey; these are markedly smaller than adults, with a similar colouration to adult females (brown or grey with 'ocellated' spots - i.e. black with white centres). We found one of these juveniles a bit further down the track: it was basking on a tree stump but then moved under the cover of some nearby vegetation (below).

Juvenile Sand Lizard in cover - RSPB Arne, Dorset

The presence of breeding Sand Lizards on heathland at Arne is encouraging news for Britain's rarest native lizard. Over the wider Purbeck Heaths National Nature Reserve, of which Arne is only a part, a programme of conservation actions aimed at benefitting the species, supported by co-ordinated monitoring by reptile surveyors, is seeking to turn around the fortunes of this endangered reptile. I am proud to play a very small part in these activities. And it's great to be able to observe these magnificent reptiles in such a beautiful natural setting.

For more information about how to identify Sand Lizards, and other lizards in Britain (both native and non-native), as well as a short list of references, see an earlier blog post - link here. This blog also contains a list of the experts upon who I have relied in gaining understanding of these species: needless to say, any errors in this blog are however my own responsibility.

For more information on conserving Sand Lizards and other reptiles contact Amphibian and Reptile Conservation.

While sightings can never be guaranteed, Sand Lizards are regularly seen from the trails at RSPB Arne. Guided walks can also be booked that will give a more detailed insight into these and other heathland species - contact RSPB Arne Events for more information.

Portland Miscellany - Wheatears, Wall Lizards and a Grey Seal

(Northern) Wheatear - Portland Bill, Dorset, UK

 A visit to Portland Bill rarely disappoints, and today's sunny weather was enough to lure the family down for a walk, lunch and some wildlife watching. Reports of good numbers of Wheatears on the Portland Bird Observatory website (link) meant that this neat migrant was top of my wish list. And it didn't take long to spot one, perched on a roadside boulder near the Bill car park. I would have to wait a little bit longer for a decent image, however; the above photo was taken on the coast path heading up the east side of the 'island' (actually not an island, but that's what everyone calls it) just north of the beach huts. It was one of an estimated 10-15 that I saw on the fields and in the nearby quarries. This is good news: the Spring migration is up and running.

One of Portland's great selling points is the diversity of wildlife that can turn up. Whilst enjoying the background chatter of Skylark song and watching Rock Pipits flit along the shoreline we noticed a Grey Seal's muzzle sticking out of the water, close in to the shore (below). A fine set of whiskers were on display.

Grey Seal 'bottling' - Portland Bill, Dorset, UK

This common behaviour is known as 'bottling' - as it apparently resembles a floating bottle - and it allows the seal to rest, and even sleep, with minimal exertion. Its eyes (not visible in this photo) were near to the waterline, and may even have been shut. It may have heard us, as it raised its head up and gave us a rather penetrating stare (below) before diving. 

Grey Seal 'bottling' - Portland Bill, Dorset, UK

I've written before about Portland's Wall Lizards (see a blog about recent sightings here and a more detailed one about identifying British lizards here). These non-native reptiles are a charming and visible addition to the local fauna, and it's always great to have an encounter. The jury remains out as to whether they have a harmful effect on native reptiles, by the way; this certainly can't be ruled out. But, as I've previously commented, they appear to occupy a distinctly different 'niche' to Common (or Viviparous) Lizards their nearest likely competitor, while their colonies on the south coast of England are well-separated from the heathland domain of the threatened Sand Lizard.

Anyway, we went looking for Wall Lizards in one of the quarries next to the coast path on the eastern side of the island, a place with several previous sightings. Although the day was sunny, a cool easterly breeze wasn't ideal for these ectothermic creatures - ectothermic meaning that they rely on external heat sources. On that point: reptiles are commonly called 'cold-blooded' - I've done it myself - but this isn't fully accurate. To be properly active, they need to reach a certain blood temperature, which in Britain is around 25-30 degrees Celsius (Inns, 2009). Obviously, such temperatures cannot be guaranteed in our chilly latitudes, even sometimes during the British summer. Today on Portland it was considerably colder, perhaps 15 degrees at the most. However, reptiles are very good at extracting what heat they can from the surrounding environment, mainly by basking in the sunshine but also by flattening themselves against warm surfaces. This morning, the best place to look for Wall Lizards was therefore in a sunny but crucially sheltered corner of the quarry. And that's where we found a couple:

Common Wall Lizard - Portland, Dorset, UK

Common Wall Lizard - Portland, Dorset, UK

The mottled pattern on the back suggests that both lizards are males, although only the second one was showing the characteristic yellow-green colour that accompanies the breeding season. Wall Lizards, and indeed Common Lizards, are relatively quick off the mark in that regard compared to Sand Lizards which will usually not begin to mate until April at the earliest. (As it happens, I saw my first Sand Lizard of the year while surveying on the Purbeck Heaths this week; it was a male without any evidence of green colouration.)

Before leaving the island we revisited the Wall Lizard colony at Cheyne Weares (further up the island's east side) that was the subject of my previous blog. By now, the sun had moved into the western sky and much of the roadside wall was in shadow. But we still found eight individuals making the most of the sunshine, including these two:

 

Common Wall Lizard - Cheyne Weares, Portland, Dorset, UK

Common Wall Lizard - Cheyne Weares, Portland, Dorset, UK

The obvious stripes on the back of each individual suggest that they are both females - although please let me know if you disagree. Also present in this colony were several much smaller lizards, likely last year's juveniles that have successfully overwintered.

As ever, Portland delivered on the wildlife front - and we had an excellent lunch at the Lobster Pot, too. With Spring now getting into gear, it won't be long before I'm back.

Portland Bill, Dorset, UK

References

Beebee, T. & Griffith, R. (2000) Amphibians and Reptiles (New Naturalist Series) London: HarperCollins.

Inns, H. (2009) Britain's Reptiles and Amphibians Wildguides

Text and images (c) Mike Hetherington

 

Searching for Early Spring Reptiles (and more)

Common Wall Lizard (male) sunbathing - Portland, Dorset, UK - 25 February 2026

After what has seemed like an endless succession of miserable, rain-sodden days, the sun has finally put in an appearance down here in Dorset. Spring is on its way, and this means that it's time to start looking for wildlife that has been hiding away over the winter months. The moth trap has been out (that's one for a separate blog), the first butterflies have been sighted and the hunt for reptiles has begun.

My searches for our cold-blooded friends have comprised both casual wanderings around likely sites in my corner of Dorset and structured survey work for the RSPB and Amphibian and Reptile Conservation (ARC) on the Poole Harbour basin heathlands carried out under licence, given the presence of protected reptile species in those areas. 

In terms of casual sightings, a walk around the Isle of Portland (not strictly an island, but that's how it's usually known) a few days ago was especially productive. I have written before about Common Wall Lizards (usually just called Wall Lizards in the UK) - here's a link to my blog. They are not native to Great Britain but appear to be thriving in a number of small colonies along the south coast, one of which can be found at Cheyne Weares on the eastern side of Portland. We have seen Wall Lizards here before in late February, and as it was a warm and sunny day, the chances of sightings seemed good.

Satisfyingly, this particular colony occupies a wall - in this case, a wall that is backed by thick scrub along a quarry edge that provides both shelter and foraging opportunities for the lizards. The first that we spotted is pictured at the top this blog, its body flattened out against the rock to maximise heat gain. The relatively thick head and mottled pattern on the back suggests that this is a male (but do let me know if you disagree). He remained quite still, apparently unbothered by our attention, and we left him to his basking.

As we walked on next to the wall, more lizards began to appear, beginning with another male:

Common Wall Lizard (male) - Portland, Dorset, UK - 25 February 2026 

This lizard had just emerged from a crevice between the stones and was clearly more alert to potential danger. Just after I took this photo, he beat a hasty retreat and vanished into cover.

Nearby, a nice group of three was rather more relaxed, allowing us to observe from a suitable distance:

Common Wall Lizards (female, male, juvenile) - Portland, Dorset, UK - 25 February 2026 

These are (from left to right) a female, a male and a juvenile; the difference between the mottled back of the male and the plainer, striped colouration of the female is easily seen. In total we saw 11 Wall Lizards along this stretch of wall, easily our highest number here. All of the males had the brownish background colour shown in the above photographs. As you'll see from my other Wall Lizard blog, males from this population can develop greener colours and a blue underside during the breeding season in April and May. What we were seeing here might have been one of the colony's first excursions into the outside world after the chilly (and wet) winter period. 

Formal transect surveys under ARC's National Reptile Survey are not due to begin until later this month. However, both ARC and RSPB organise early season visits to look for Adders that have emerged from their over-wintering sites (or hibernacula). These take place on lowland heathland around Poole Harbour, a superb place for reptiles which hosts all six native British species:

Lowland heathland at RSPB Arne, Dorset, UK - prime reptile habitat

One of the key aims of an Adder emergence survey is to find the locations of any over-wintering sites to ensure that they are not inadvertently damaged by heathland management operations. Unfortunately, despite two half-day searches - at Arne and Grange Heath respectively - no Adders were sighted. We know from previous records that they will be around, but it seems that conditions on the day(s) weren't right for them to show themselves. 

One compensation was my first Slow Worm sighting of the year (below). 

Slow Worm (female) - Grange Heath, Dorset, UK - 5 March 2026

Slow Worms are legless lizards that, at first sight, might be mistaken for a snake. Here's a link to my British lizard identification blog. The slightly darker striping on the sides of this Slow Worm suggests that she's a female.

A couple of magnificent beetles were also out and about at Arne. This marvellous three-'horned' Minotaur Beetle (below) is one of the dung beetle family (Geotrupidae). They dig burrows which they fill with rabbit (or other) droppings, making an ideal place to lay eggs. The 'horns', which are absent from females, must have an aggressive function, allowing males to defend resources such as dung piles or burrows (or even females) from their rivals. 

Minotaur Beetle (male) Typhaeus typhoeus - Arne, Dorset, UK - 26 February 2026

Also wandering along the heathland floor was this Bloody-nosed Beetle (below), another early emerging species. This is perhaps an atypical member of the leaf beetle family (Chrysomelidae), as it is usually found bumbling slowly along the ground rather than sitting higher up in the foliage. Unlike most beetles it's flightless, its larvae feeding on bedstraws (Galium sp). The dramatic-sounding name comes from its habit of exuding an unpleasant reddish liquid from its mouth to discourage would-be predators. We didn't aggravate it though, and it went safely on its way.

Bloody-nosed Beetle Timarcha tenebricosa - Arne, Dorset, UK - 26 February 2026

So, despite the absence of Adders (for the time-being - more surveys are planned) there was much to see on the Dorset heathlands. There usually is: these places are full of welcome wildlife distractions. And on that theme, I'll leave you with another over-wintering heathland resident - this Peacock butterfly (below) that we found on a pile of logs at Grange Heath, its colours especially vivid in the afternoon sunshine.

Peacock Aglais io - Grange Heath, Dorset, UK - 5 March 2026

References

Beebee, T. & Griffith, R. (2000) Amphibians and Reptiles (New Naturalist Series) London: HarperCollins.

Inns, H. (2009) Britain's Reptiles and Amphibians Wildguides

Jones, R (2018) Beetles (New Naturalist Series) London: HarperCollins. 

Speybroeck, J. et al. (2016) Field Guide to the Amphibians & Reptiles of Europe (British Wildlife Field Guides) London: Bloomsbury.

Text and images (c) Mike Hetherington

 

Iguanas and Basilisks - Costa Rica's Big Lizards

 

Green Iguana - Muelle, Costa Rica

As one of the world's most biodiverse countries, Costa Rica contains a huge variety of wildlife. Birds and mammals may be the biggest attractions, but you can easily get diverted by the supporting cast. And it was the reptiles, especially the large lizards, that caught my attention when I visited in November 2024.

Costa Rica contains around 250 species of reptile (compared to only six in my native Great Britain). While many of these are snakes, which tend to keep themselves to themselves, the ones that you are most likely to encounter are certainly the lizards. Unsurprisingly, it's the big lizards that are the most obvious.

And there are some real whoppers. This blog post looks at the two most conspicuous groups - the large iguanas and basilisks. 

Iguanas are the biggest of them all. Costa Rica hosts three species from the iguana family, of which two fall within the scope of this blog post. (The third, the Dwarf Spiny-tailed Iguana, is a secretive and endangered species only found in the extreme north of the country.)

Top of the tree, sometimes literally, is the Green Iguana (below - and at the start of this blog post). This is the archetypal iguana, indeed its scientific name is actually Iguana iguana. You cannot get more iguana-ish than that! They range across much of Central and South America and are native to some of the southern Caribbean islands, as well as having been introduced to Florida, where they're making a bit of a nuisance of themselves.

Some authorities have split the Central and South American Green Iguanas into two separate species, but I'm sticking here with the name used by international conservation body the IUCN.

Green Iguana - Sarapiqui, Costa Rica

Green Iguanas are huge - adult males can exceed two metres in length. They can crop up across much of lowland Costa Rica, although are more likely to be encountered in protected areas.  If you're in northern Costa Rica then the place to head for is the town of Muelle on the road up to Los Chiles. And specifically to the café next to the Puente de las Iguanas - which is a good sign.    

Here, the Green Iguanas are an established tourist attraction: although wild, the café owners (and probably visitors) feed them (cabbage seemed a favourite), and we saw plenty hanging around. Green Iguanas are fairly strict vegetarians, although they do look capable of taking a chunk out of your thigh - if only they could be bothered to stop snoozing.

Other places to see Green Iguanas include the excellent rainforest reserve at Tirimbina (web link here). When we arrived there, one was perched high in a tree above the car park (below). They are excellent climbers.

Green Iguana in a tree - Tirimbina, Costa Rica

Green Iguana - Muelle, Costa Rica

The large size of Green Iguana is its best identification feature. Despite the name, Green Iguanas aren’t all green. Those at Muelle displayed a wide range of colours, as can be seen in the image above. Males turn orange in the mating season, which starts in December so this chap (who I photographed in November) may have been a bit quick off the mark. By the way, notice also the prominent circular scale sitting below the eye (the ‘sub-tympanic shield’), which is also a distinguishing feature of the Green Iguana. I can't find out whether it has a specific function, and would welcome comments from anyone with more information about this.

In Costa Rica, Green Iguanas can only be confused with the country's other large iguana - the Ctenosaur or Common Spiny-tailed Iguana Ctenosaurus similis (below). However, those are smaller (‘only’ up to about 1 metre long) and lack the sub-tympanic shield that characterises its larger relative.

Ctenosaur - near Chomes, Costa Rica

The Ctenosaur is the more common large lizard on the Pacific side of Costa Rica's central mountain chain, but its range doesn't extend over onto the eastern (Caribbean) slopes or lowlands. This one was sitting on a fencepost next to the road, eyeing us with a rather baleful expression. But it soon tired of our attention and decided to vanish rapidly into a hole in the top of the post with a surprisingly fluid motion. This was our only sighting of this spectacular reptile.

The second group of lizards that I'm looking at in this blog posts are the Basilisks, of which there are three Costa Rican species. These are a bit confusing, as all have a broadly similar body pattern. It doesn't help that there is no consistency in their naming; these are species where it pays to keep an eye on the formal scientific names. For example, all three species have been called the 'Jesus Christ Lizard' owing to their ability to run over the water on their hind legs. I witnessed a juvenile do this on a small stream on the Pacific coast, and can vouch for the fact that it's a startling and effective method of escaping from potential predators. It doesn't help to distinguish between the three species, though.

Brown Basilisk - Tirimbina Rainforest Reserve, Costa Rica 

We only encountered two of the three species on our trip in November 2024, the first of which was the Brown Basilisk Basiliscus vittatus (above) in Tirimbina rainforest reserve. It was our guide Pat O'Donnell (website link here) who first spotted the lizard, which was doing an excellent job of blending in with the leaf litter on the forest floor. But perhaps as a result of being noticed, it decided to climb up onto a low branch allowing me to get this lovely portrait. This species is less associated with streams and watercourses than the other two, and can be found at higher altitudes - although it's still able to do the running-over-water trick if it needs to. 

As in all three basilisks, Brown Basilisk has a prominent, pointed crest (or casque) on the head. But, unlike the other two species, adults have only a low crest on the back and a line of enlarged scales (looking like small spines), rather than a crest, along the top of the tail. Helpfully, it is only found on the eastern (Caribbean) side of Costa Rica's central mountain chain. Costa Rica is at the southern end of this species' distribution; heading north, its range extends into Mexico.

Both of my field guides (I've listed them at the end of this post) use the name 'Striped Basilisk' for this species (although Henderson also mentions Brown Basilisk). This is unhelpful, to put it mildly! As can be seen from my images, both this and the next species show prominent stripes. And, of course, both are mostly brown! In writing this blog, I have used the IUCN nomenclature for the sake of clarity.

So, let's look at basilisk number two:

Common Basilisk - near Golfito, Costa Rica

This is the Common Basilisk Basiliscus basiliscus. We found this one basking on a tree trunk above a stream in the Golfito Wildlife Refuge on the Pacific coast. In contrast to the previous species, the Common Basilisk is only found on the western side of Costa Rica's central mountains, although its range extends into the Central Valley where suitable habitat is available. In contrast to the previous species, Costa Rica lies at the northern end of its range, which extends south into Colombia and Venezuela. These two reptiles provide a nice illustration of one of the reasons why this small country is such a diverse wildlife destination; it sits at the cross-roads where Central American species meet those from tropical South America. 

Common Basilisks have a similar pointed crest or casque to Brown Basilisks. The key difference is that adults have conspicuous sail-like crests on both the back and the tail, as is shown in the one pictured below, which we also found in the Golfito area of Costa Rica's southern Pacific lowlands.

Common Basilisk - near Golfito, Costa Rica

One of my field guides (Twan Leenders) refers to this species as the Brown Basilisk, which as I've explained above can only add to the confusion between these two reptiles. If you stick to the accepted international terminology it's a lot clearer.

Unfortunately we didn't encounter Costa Rica's third basilisk species - the Green Basilisk Basiliscus plumifrons - so I can't provide a photograph. What I can do is refer you to websites that do, such as its page on the IUCN Red List site (link) and this rather excellent article on the Tetrapod Zoology blog (link) which contains a feast of basilisk-related information. 

Within Costa Rica, Green Basilisks are mainly found on the eastern (Caribbean) side of the mountains, although there is also a population on the Osa peninsula in the Pacific-side lowlands - which is the southern end of their global range. As this only extends as far north as Honduras, these basilisks have by far the most restricted range of our three species. The bright green colours is their main identification feature, along with bright yellow eyes and (in adult males) a generally more prominent crest (casque) on the head. But be warned: this species is also known as Emerald Basilisk and Double-crested Basilisk. Once again, I've used the IUCN nomenclature.

(For the sake of completeness, I should add that there is a fourth basilisk species that doesn't make it to Costa Rica. This is the Western Basilisk which is found in Colombia and Ecuador. They are green, have a rounded casque and serrated scale along the back. Sadly, I haven't encountered any on my travels.)

As an aside, it's worth noting that the basilisk has long been referred to in European literature as a mythical beast, going back at least as far as Roman times (for example the works of Pliny the Elder). It always seems to be some sort of reptile, but generally in snake rather than lizard form. Both its gaze and venom were meant to be lethal, its only weakness being (wait for it) the scent of a weasel. It popped up as a massive snake-like monster in Harry Potter and the Chamber of Secrets, where our heroes had to resort to a non-weasel-related method of basilisk disposal. None of which explains why the name has been bestowed upon a genus of entirely non-venomous Neotropical reptiles.

I'll leave you with a close-up of a particularly prehistoric-looking Common Basilisk that we found in a small area of remnant rainforest near Alajuela in Costa Rica's Central Valley. 

References & Websites:

Halliday, T. and Adler, K. ed (2002) The New Encyclopedia of Reptiles and Amphibians. Oxford: OUP

Henderson, C.L. (2010) Mammals, Amphibians and Reptiles of Costa Rica. Austin: University of Texas Press.

Leenders, T. (2023) Pocket Guide to the Amphibians and Reptiles of Costa Rica. Hellbender-Zona Tropical: Cornell University Press.

Sasa, M., Arias, E. and Chaves, G., 2025. Annotated list of amphibians and reptiles of Costa Rica: The role of the Museum of Zoology in cataloging the country’s herpetological diversity. Revista de Biología Tropical, 73(S2), pp.e64536-e64536. [Online]

IUCN Red List website - link

Pat O'Donnell's website - link

Tetrapod Zoology website - link

Text and images (c) Mike Hetherington

How to See a Smooth Snake

 

Smooth Snake - RSPB Arne, Dorset, UK

Smooth Snakes are the rarest, the hardest to find and (for me) the coolest of Britain's reptiles. 

Three things make it difficult to find a Smooth Snake. First, they have a massively restricted range. Second, even when you are on their home turf, they aren't exactly showy, preferring to skulk low down under vegetation. Third - and this is the really tricky one - they (and their habitats) are strictly protected by law. Don't go looking for one by yourself without a licence!

I'll look at each in turn and then suggest how you might get that elusive encounter. But I'll start with a couple of disclaimers: I am a volunteer reptile surveyor for Amphibian and Reptile Conservation and all of the Smooth Snake images in this post have been taken under relevant licences. 

Smooth Snake Identification

First things first: how would you recognise a Smooth Snake if you saw one?  

Smooth Snake - RSPB Arne (handled under licence)

Smooth Snakes are smaller than you might expect, being no longer than 50-55cm long. The background colour is often brown or grey (or a brownish grey!), with conspicuous spots along the back. These spots are usually brown, but can be darker in younger individuals, as in the image at the start of this blog post. But bear in mind that there are some dark (melanistic) individuals out there.

As with many snakes, the head is the best place to look for identification features. Smooth Snakes have a prominent heart-shaped mark (or 'crown') on the top of the head, which can range from black to brown as these photos show. The pattern is not uniform, allowing individuals to be identified from their particular pattern. They also have a dark horizontal stripe through the eye.  

Here's a close-up of the head of that Smooth Snake:

Smooth Snake head (detail)

Possible Confusion Species

If you are in the right part of the country - and I'll come to that shortly - then you could also encounter two other snakes, as well as one legless lizard. I'll take these in turn.

The easiest snake to rule out is the Grass Snake (below).

Grass Snake - RSPB Radipole

Grass Snakes are Britain's most distinctive snake. Generally much larger than Smooth Snakes, they can be 80cm to one metre long but sometimes more. The one in the photo above was relatively small. Grass Snakes are often found near, or sometimes in, ponds and other water bodies: frogs, toads and newts form a big part of their diet. But garden compost heaps are also popular places for them to hang out.

Apart from their respective sizes, there are three main differences between Grass Snakes and Smooth Snakes:

• Grass Snakes have a distinct collar with yellow or orange patches in front of a conspicuous black mark. This collar is absent in Smooth Snakes. Here's a close-up of that Grass Snake's head:

Grass Snake head (detail)

• The background colour of Grass Snakes is usually greenish-olive, compared to the usual grey-brown of Smooth Snakes. (But bear in mind that the colour of both species can vary.) 
• Although both Smooth and Grass Snakes are spotted, the markings on Grass Snakes tend to be a sharply distinct black colour and located along the flanks rather than the back. As already mentioned, the spots on Smooth Snakes are usually brown, although young Smooth Snakes can have darker and more obvious markings than adults. 

Rather more confusing is the Adder (below), Britain's only venomous snake:

Adder - Isle of Jura, Scotland

Adders are often in a similar size bracket to Smooth Snakes (40-55cm long), although female Adders can be bigger (up to 70cm). It should go without saying that Adders are dangerous (they do bite people and their venom is potentially fatal), so keep your distance and do not handle them! 

At first glance, Adders and Smooth Snakes share some characteristics: as well as being of a broadly similar size, both species have regular patterns on their backs and dark marks on the top of their heads. However, Smooth Snakes have spots on their back while Adders have a dark zig-zag pattern. But note that Adders are variable in colour, and some of the lighter examples can look similar to Smooth Snakes. Black Adders are more common than melanistic Smooth Snakes.

Also, the pattern on the top of an Adder's head is a dark V or X shape (see below) while, as already described, Smooth Snakes have a heart shaped mark. 

Adder head with V-shaped mark - West Bexington, Dorset

The good news is that there is a definitive way to distinguish Adders from either of the other two native British snakes: Adders have red eyes with a vertical pupil (see below). Smooth Snakes and Grass Snakes have eyes with round pupils. This is best viewed with close-focus binoculars or by taking photos with a decent camera lens. Keep well separated from the snake itself.

Adder head showing vertical pupil - West Bexington, Dorset

For the sake of completeness, don't forget Slow Worms. At first sight, these legless lizards can be mistaken for snakes, but a closer look will reveal a lizard-like head, a more 'chunky' profile than a snake and a characteristically smooth and shiny skin. In fact, they can look smoother than a Smooth Snake. If you get really close to a Slow Worm then you'll see that (like all lizards) they blink. Snakes don't.

Not a snake! Slow Worm in the garf- Dorset, UK

Slow Worms are common, and welcome, residents of less-tidy gardens (my garden included). But they are also found on lowland heaths that are occupied by Smooth Snakes. Indeed, Slow Worms form part of the diet of Smooth Snakes, although Sand Lizards and small mammals (especially young mice) are more commonly eaten. There's more about lizards in a previous blog post.

An excellent reptile identification guide is available as a free download from Amphibian and Reptile Conservation.

Smooth Snake habitat - lowland heath at RSPB Arne, Dorset, UK

Seeing Smooth Snakes

In Britain, Smooth Snakes are only found on the lowland heathlands of southern England, especially those in Dorset, Hampshire and Surrey. Reintroductions have taken place in other southern counties including in Devon on the Pebblebed Heaths National Nature Reserve - more details here.

There is a UK distribution map for Smooth Snake in the National Biodiversity Network Atlas.

In my patch of Dorset, Smooth Snakes are present on various heathlands in Purbeck (the area south of Wareham) and the wider Poole Harbour basin. There are good numbers (35-40 individuals according the RSPB's news release that I've linked above) at RSPB Arne, where I am a volunteer, although they are rarely (if ever) seen by visitors; most casual snake sightings on the reserve tend to be of Adders. While Adders can sometimes be seen basking on open ground, Smooth Snakes are more more reluctant to emerge from the stands of deep heather where they spend most of their time. Even when warming up, they will often be wrapped around heather stems, providing very effective camouflage. If you have seen a Smooth Snake out in the open, and it does happen, then you have been extremely lucky.

Smooth Snake vanishing into the heather - RSPB Arne

As already mentioned, Smooth Snakes are strictly protected (here's the relevant legislation). Searching for one by yourself risks breaking the law, as well as disturbing a fantastic species that I'm sure we all want to protect. Fortunately, there are better ways of seeing Smooth Snakes in the wild.

Several of the organisations that own or manage heathland reserves arrange guided walks where a licensed surveyor will take groups out in search of reptiles. In the right locations these have a very good chance of seeing Smooth Snakes, as well as other heathland stars such as the spectacular Sand Lizard - although as with all wildlife encounters nothing is guaranteed. An added advantage is that you will learn a bit about the habits and ecology of the species concerned.

Some of the places and organisations that run reptile walks in Smooth Snake habitat are listed below, but bear in mind that at the time of writing this (November 2025) we are out of the reptile viewing season, so most events are unlikely to be scheduled before Spring 2026:

RSPB Arne - link here.

Dorset Wildlife Trust - link here

Dorset Heaths Partnership - link here

Surrey Wildlife Trust - link here

Amphibian and Reptile Conservation (link here) run more in-depth training courses for reptile surveyors which are well worth considering if you live near areas of good reptile habitat and would like to spend more time surveying and helping to conserve these fascinating creatures. 

Further Reading

Beebee, T. and Griffiths, R. (2000) Amphibians and Reptiles. (Collins New Naturalist). Excellent detail about the ecology and life histories of Britain's snakes.

Inns, H. (2009). Britain's Reptiles and Amphibians. (Princeton Wildguides). Really useful, as it focuses upon the few British snake species, and well illustrated. Howard is the person holding a Smooth Snake in one of the photos in this blog.

Speybroeck, J. et al. (2016) Field Guide to the Amphibians & Reptiles of Europe (British Wildlife Field Guides) London: Bloomsbury. This contains far more detail that you need for snake-spotting in Britain, but it's good to understand our species in their wider European context.

 

Know Your British Lizards!

 

Britain doesn't have many lizards, so surely it's not difficult to work out which species is which? Wrong! I sometimes get confused, and I know that I'm not alone. It doesn't help that lizards don't always hang around to give you a good view. Too often, you only see a flash of movement or catch a glimpse of a tail vanishing at speed under a rock or into a bush. 

Anyway, as a (now qualified) reptile surveyor I've been learning the key identification features that separate Britain's lizards. In doing so I have relied heavily on guidance and training from experts including Sue Searle, Howard Inns, Rick Sharp, Gary Powell, Nick Moulton and the reptile surveyors at RSPB Arne, as well as the two field guides mentioned at the end of this post. (Needless to say, any errors in this blog are my own responsibility.) My notes have ended up as this blog post, which I hope that you find useful. The photos are all my own. Images of Sand Lizards, which are a protected species, were taken under licence. 

(This blog post was updated with additional information and images in May and June 2026). 

It's also worth knowing that Amphibian and Reptile Conservation, who do much to conserve and promote Britain's reptiles, have prepared a useful (and free) online reptile identification guide which covers snakes as well as lizards. It can be downloaded from their website (link here). 

Sand Lizard (male) - RSPB Arne, Dorset

I'm focusing here on four species: three lizards that look like lizards - Common (or Viviparous) Lizard Zootoca vivipara (pictured at the top of this blog post), Sand Lizard Lacerta agilis and the non-native Wall Lizard Podarcis muralis - as well as the legless Slow Worm Anguis fragilis. I've included Wall Lizards because they have become well-established in a number of mainly coastal sites in the south of England - many of which are in Dorset where I'm based - see my blog post here.

I've concentrated on features that can be distinguished by the field observer, ideally with a photograph, rather than anatomical details that require an 'in-hand' examination such as femoral pores and supraciliary granules. For most of us this is simply impractical, and for Sand Lizards it would be illegal without a licence, as that species is protected in the UK - so don't even think about picking one up! I'm sure that most of us would rather avoid disturbing these lovely creatures in any event.   

The Slow Worm is probably the most common of all our reptiles, being found right across mainland Britain. Having no legs, it can be clearly distinguished from our other lizards, looking in the first instance more like a snake. But on closer inspection you'll see that they have a less slender and more chunky profile than our three native snakes, as well as a distinctly Common Lizard-like head. 

I've done a blog post about identifying Britain's three native snakes, focusing on the lovely Smooth Snake - link here.

Slow Worms are the most likely lizards to turn up in a back garden. If they arrive in yours then count your blessings and try to maintain a patch of undisturbed long grass and a few bushes for them. Compost heaps go down particularly well.

Slow Worm (male) - Dorset

The photo above shows a male Slow Worm. These are usually a uniform light brown colour sometimes dotted with startling blue spots. In contrast, the females tend to have darker sides and/or a dark stripe along the back (the dorsal or vertebral stripe) - see below. 

Slow Worm (female) - Dorset

The dark sides and dorsal stripe are also characteristic of juvenile Slow Worms. However, these will (unsurprisingly!) be much smaller than adults with brighter and more clearly defined markings. The dorsal stripe on juveniles often ends in a dot next to the head, as in the example below.

Slow Worm (juvenile) - Dorset

Right, onto lizards with legs. These are more tricky, but at least they do look like lizards.

First, the magnificent Sand Lizard. 

Sand Lizard male - RSPB Arne, Dorset

Sand Lizards are the most distinctive of Britain's legged lizards. (I did a blog about them last year, which you can find here). The key distinguishing features are set out below, but please be aware that Sand Lizards are a strictly protected species, so keep your distance and avoid disturbing them or their habitat.

• Sand Lizards are larger than either Common or Wall Lizards, with a total length of up to 25cm rather than 22cm (Wall Lizard) or 20cm (Common Lizard). Not that this helps with smaller individuals!
• Sand Lizards usually have two white or cream-coloured streaks down the back (dorsal streaks) - see the photo below.
• The spots on male, female and juvenile Sand Lizards are usually ocellated, meaning that they have a lighter ("eye-spot") in the middle. This is a key feature that is not present on Wall Lizards, although you need to look carefully at the spotting on female Common Lizards especially when they are flattening themselves while basking in the sun.
• As the photo above shows, adult male Sand Lizards usually have striking green flanks during the breeding season. But beware! Male Wall Lizards can also show green, which gets brighter during the breeding season (see the photo later in this blog post) and you can occasionally see green Common Lizards. However, in both cases, any green on Common and Wall Lizards extends across the back, while on male Sand Lizards it is restricted to the sides. 
• Female Sand Lizards are brown or grey all over, dotted with ocellated spots (below). Females are less likely to bask out in the open than the more colourful males, sometimes preferring light vegetation cover. Juvenile Sand Lizards of both sexes have similar markings to adult females, which can make them hard to distinguish; their smaller size is usually the best identification feature (see photo below).
• Sand Lizards are generally more heavily built, or "chunky", than Common or Wall Lizards.
• The final point to bear in mind about Sand Lizards is that in Britain they have a limited distribution, being confined generally to heathland in Dorset, Hampshire and Surrey along with sand dunes near Southport, Merseyside. They have been more recently introduced to sites in Devon, Cornwall, Berkshire, North Wales and Kent (possibly more). However, I'm not aware of any British locations where Sand Lizards co-exist with Wall Lizards.

Basking female Sand Lizard - RSPB Arne, Dorset

Juvenile Sand Lizard - RSPB Arne, Dorset.

Next, Common Lizards. These are also known as Viviparous Lizards, as they give birth to live young rather than the egg-laying Sand and Wall Lizards, but I'm using Common Lizard in this blog for simplicity. Like Slow Worms, the range of Common Lizards extends in theory (and on the distribution maps of many field guides) across the whole of mainland Britain. But in practice they are more scarce, and may be absent from large areas of intensively farmed land or built development. Generally, they favour undisturbed and open landscapes such as heaths or downland; in the former setting, their range overlaps with that of Sand Lizards although Common Lizards tend to prefer damper and grassier places while Sand Lizards are happier in drier areas dominated by heather and gorse.  

Common Lizard - Higher Hyde Heath, Dorset - showing re-grown tail

Distinguishing male and female Common Lizards is far less easy than for Sand Lizards. Males are generally more speckled, while females tend to look more stripey. I think that the photo above is probably a male, given the flecked pattern on its back, but the obvious light-coloured stripes give me some pause for thought. Nobody said it would be straightforward! (If the belly is visible, which it isn't in this image, then things get easier: males have a yellow-orange underside, while females are a plainer beige colour below.)

Unhelpfully, Common Lizards can show considerable colour variation. One with a greener tinge is pictured below.  Black, also called melanistic, individuals also occur, although rarer here in Dorset.

Common Lizard - Higher Hyde Heath, Dorset

So, what are the key identification features that distinguish Common Lizards from Sand and Wall Lizards? As noted above, both Sand and Wall Lizards have very restricted distributions in Britain. If you are not on lowland heath or coastal dunes then you are highly unlikely to be looking at a Sand Lizard, while Wall Lizards tend not to stray far from their known colonies, which are mostly in Southern England (see here for more details). However, if you are in an area of possible confusion then the following may help:

• Compared to Sand Lizards:
• Common Lizards generally do not show any green colour, but if green is present then it will be right across the back and not confined to the sides. It will also usually be less vivid than the green of a male Sand Lizard.
• Any spots on Common Lizards will usually not be ocellated, so will appear as white flecks rather than dark spots with a central white "eye". 
• Common Lizards are smaller and more slender, with much less bulky heads than Sand Lizards (see photos below).

Common Lizard - head 

Sand Lizard - head

Wall Lizard - head

• Compared to Wall Lizards:
• Common Lizards tend to be slightly smaller than Wall Lizards, although this is not always obvious and you very rarely (i.e. never!) see both species side-by-side to compare.
• The markings on Common Lizards are generally either speckles (including patches of white) on the males or light-coloured stripes on the females, while Wall Lizards usually have more mottled markings (see photo below).
• Common Lizards have a blunter snout than the more pointed snout of Wall Lizards. This is just about apparent in the respective head photos above, but in the field I find that I need either a very  good look at the lizard or a decent photograph.
• Although by no means definitive, Common Lizards tend to be seen in flatter, grassy areas, while Wall Lizards are usually not far away from a vertical rocky habitat: they are well-named. Even though the Wall Lizard photographed below was basking on leaf litter, it was less than a metre from a large south-facing stone wall.

Wall Lizard showing mottled pattern - Abbotsbury, Dorset

Finally, this brings us to Wall Lizards. Strictly these are called Common Wall Lizards, as there are a wide variety of wall lizard species across Europe (see Speybroeck et al., 2016), but I've deleted the "Common" in this blog for reasons of clarity, given the risk of confusion with Common Lizards.

Wall Lizard male with bright colouration - Abbotsbury, Dorset

The main identification features that distinguish Wall Lizards from Sand and Common Lizards have already been described above, so there's no need to restate them again in detail. The important thing to remember is that the colouration of Wall Lizards is very variable, and males of the populations of southern England can have either green or brown backs depending upon where the original introduction was sourced (generally green from Italy and brown from France). Colour alone is generally not a reliable way of separating Wall Lizards from Common Lizards, although a useful tip is that some male Wall Lizards show a blue patch on the side of the belly - see the example below from Portland, Dorset. As far as I'm aware this is not a feature found in Common Lizards.

Wall Lizard male with brown back and blue sides to belly - Portland, Dorset

Anyway, I hope that this is helpful - do let me know if I've made any errors or if anything isn't clear. I intend to update this post as I get more field experience with these species.

Postscript: For the sake of completeness, I should add that there is a further lizard species on British soil - the (Western) Green Lizard Lacerta bilineata, which as well as being a native of Jersey, an island that also hosts native Wall Lizards but no Common Lizards, has a longstanding introduced population in Bournemouth of all places. Western Green Lizards are large (up to double the size of a Sand Lizard) and truly spectacular. I have yet to get a decent photograph of one, but in compensation here's a magnificent (and very similar) Eastern Green Lizard L. viridis that I photographed in northern Greece. Enjoy!

(Eastern) Green Lizard - Lake Kerkini, Greeve

References

For reptile identification:

Inns, H. (2009). Britain's Reptiles and Amphibians Wildguides. Especially useful, as it focuses upon the few British species (plus introductions).

Speybroeck, J. et al. (2016) Field Guide to the Amphibians & Reptiles of Europe (British Wildlife Field Guides) London: Bloomsbury. Frankly, this is rather daunting given the much greater diversity of lizard species on the continent and the taxonomic complications of some groups (such as Iberian Wall Lizards). But it's good to see the British species in their wider context.

Not a field guide, but the following book is another essential reference:

Beebee, T. and Griffiths, R (2000) Amphibians and Reptiles (Collins New Naturalist series) London: HarperCollins