Introducing Common Spring Moths

 

Oak Beauty Biston strataria - Dorset 23.3.26

If you are new to moth recording then Spring is a great time to start. Moth numbers are manageable, so you can proceed at a relaxed pace without the stress that comes with a big summer catch. Mornings are still chilly, so any moths that you do catch are likely to be docile and will wait patiently while you work out what you've got. All in all, Spring mothing provides excellent foundation for the more hectic days that are yet to come.  

A recent run of cold nights has discouraged me from running the moth trap, but yesterday seemed warm enough to give it a go - and I'm pleased that I did. A total of 45 moths from 10 species represents a good return for the garden trap at this time of the year. As it happens, many of Spring's 'usual suspects' turned up, which is a good excuse for a blog post.

Last night I used my normal 125W mercury vapour Robinson trap. We're in a small village about a mile inland from the Dorset coast, which is great for attracting interesting migrant moths in Summer and Autumn (one for a separate blog!), but is notoriously slow at delivering the goods on Spring's colder nights. This may be because the village sits on a cool north-facing slope, a problem amplified by the need to avoid dazzling our neighbours which means that I run the trap in a north-facing rear garden. 

Anyway, that's enough excuses! As I explained on a previous moth identification blog, the UK's larger moths (aka 'macro-moths') are dominated by two main families - the noctuids and the geometrids. I've described the key features of these (and other) families in that blog post (link here), but in essence the noctuids are generally thick-set and chunky, while the geometrids tend to rest more like butterflies, with their wings usually (but not always) spread open like the Oak Beauty pictured at the start of this post. Both are well-represented at this time of year, while other moth families may be harder to track down.

Noctuids

Three species tend to dominate the trap at this time of the year, all noctuids. First, the Hebrew Character (below), which accounted for almost a third of the moths in my trap this morning.

Hebrew Character Orthosia gothica - Dorset 23.3.26

The saddle-shaped black mark on the wings of this moth is the key identification feature. No other Spring-flying moth has this, although if you are using AI identification apps you need to be aware that there is a similar (and also common) moth of Summer and Autumn called the Setaceous Hebrew Character. If you want to know more about moth identification resources then have a look at this blog that I posted a couple of years ago. Hebrew Character moths are found across most of Britain and Ireland; they over-winter in a pupa (cocoon) and emerge to feed on the flowers (catkins) of willows and sallows. 

This food source is also the target of the second common Spring noctuid - the Early Grey:

Early Grey Xylocampa areola - Dorset 23.3.26

Early Grey moths have a marbled pattern that can at first appear confusing, but once you have got your eye in then it's easily recognised. Although a few other species appear superficially similar (such as Shears), their flight period usually will not coincide with that of Early Grey - which will be over by May. The Early Grey has a widespread distribution across most of England and Wales, but is more patchy in Scotland (outside the Central Belt) and Ireland.

The third common Spring noctuid needs a bit more thought. This is the Common Quaker:

Common Quaker Orthosia cerasi - Dorset 23.3.26

In many ways, Common Quakers are the classic noctuid moth. I use an image of one in my moth identification course to illustrate some the main wing markings that are so important for getting a successful ID. These are the oval and kidney markings on each wing (in the jargon these are the 'orbicular and reniform stigmata'), which are neatly outlined in white, and the conspicuous white cross-line (the 'postmedian fascia'). Common Quakers are frequent across most of Britain and Ireland, especially in woodland, and regularly turn up in garden traps. But do beware: there is a very similar species (Vine's Rustic) that can easily be confused for Common Quaker; however, Vine's Rustic flies later in the year. By the time that June arrives the Common Quakers should have disappeared.

Less common, but still frequently recorded in England and Wales (less so in Scotland and Ireland) is the Small Quaker:

Small Quaker Orthosia cruda - Dorset 23.3.26

Like its namesake, Small Quaker also has white-lined oval and kidney markings. However, they are smaller and less distinct than on Common Quaker, and there is often a dark splodge within the kidney. Also, the moth is generally lighter in colour and plainer in appearance. It's not really a looker, I'm afraid. As the name suggests, Small Quakers are usually smaller than Common Quakers, although both species are variable in size and there can be an overlap. Here they are side-by-side this morning; while you can make out the size difference, it's not exactly obvious:

Small Quaker (left) and Common Quaker (right) - Dorset 23.3.26

For the sake of completeness here, I'm adding in a moth that didn't appear last night (and in fact hasn't appeared here yet this year) but which is relatively common at this time of year despite experiencing recent declines in both distribution and abundance. This is the Powdered Quaker (the photo is from last year):

Powdered Quaker Orthosia gracilis - Dorset 3.4.25

The key identification feature here is the generally speckled appearance, which is usually obvious despite some variation in the background colour - although most of the ones that I see are the dirty creamy-grey colour shown above. Powdered Quakers are found over most of England and Wales, but in Scotland are more common in the south and west. 

The common English names of the UK's moths are a source of much interest. They can be quirky (for example the Mother Shipton), descriptive (the Silver Y springs to mind) or just plain bizarre (like the Ni Moth). Many are rooted in history, dating back to a wave of moth-naming in the 1600s and 1700s. The various Quakers surely date from this period.

Unfortunately, such names are unreliable when it comes to understanding how moth species are classified and related to each other. If you've noticed the scientific names on this blog's photo captions, you will see that Common and Small Quakers closely related as well as similar in appearance: they are part of the same genus (Orthosia). But so is the Hebrew Character, which has very different wing markings. The final two noctuids that I'm introducing in this blog underline this confusion. First is the Clouded Drab, which is also in the Orthosia genus:

Clouded Drab Orthosia incerta - Dorset 23.3.26

If it could have a say in the matter, the Clouded Drab would probably be less than chuffed with whoever decided on its common name. Although rather plain, its colour and patterning can have a subtle charm. While its appearance can be variable (the scientific name incerta means 'not fixed'), it can normally be recognised by its large size (bigger than all of the previous moths), rather pointed wing tips and the generally muted oval and kidney markings (although these can be more obvious than in the example pictured above). Two similar species (Lead-coloured Drab and Northern Drab) are much more localised and I have yet to see either in my trap. Clouded Drab has a similar distribution to Common Quaker.

My last noctuid is Twin-spotted Quaker (below), which despite its name is not in the Orthosia genus:

Twin-spotted Quaker Anorthoa munda - Dorset 23.3.26

This is also a large moth, similar in size to Clouded Drab, and as its name suggests is usually recognised by the presence of two obvious black dots near to the outer edge ('termen') of the wing. In the example that I caught this morning (above) these dots are actually orange - and not very obvious. But they are there if you look. I should explain at this point that the way that moth wings are described can be confusing to the newcomer. By convention, the base of a moth's wing is the point at which it joins the moth's body (thorax), which is usually at the top of most moth images. The outer edge (or termen) of the wing is therefore the bit that's furthest away from the base, which in this case is at the bottom of the photo. It does make sense, but it also needs a bit of getting used to. Anyway, Twin-spotted Quakers are fairly common in England and Wales and seem to be spreading north in Scotland.

Geometrids

Geometrids (or geometer moths) seem to be much more scarce in the Spring months. Only three species have turned up here so far in 2026, although as I've already said it has been a quiet start to the year. The most spectacular is undoubtedly the Oak Beauty pictured at the start of this blog. Here's another one from a couple of years ago:

Oak Beauty Biston strataria - Dorset 22.1.24 (an early arrival)

Oak Beauty is one of the most sought-after Spring arrivals, and it's always nice to see. The two reddish-brown jagged bands across the wings are found in no other UK moth species. Despite the name, the caterpillars (larvae) of this moth feed on a range of broadleaved trees and shrubs - not just Oaks. They are widely distributed across England and Wales but may be spreading into Scotland. It is one of several moth species that are showing a curious trend: while overall abundance is decreasing, their distribution is widening.  (There is more about this in my blog post on insect decline - link here.)

Similar in shape, but not markings and colouration, is Brindled Beauty (below). Unfortunately I'm still waiting for this one in 2026, so here's an example from last year:

Brindled Beauty Lycia hirtaria - Dorset 3.4.25

Brindled Beauty is widespread across Wales, southern and central England and the Scottish Highland, but appears less common in northern England and southern Scotland - a curiously scattered distribution. Its dark markings separate it from the male Pale Brindled Beauty (below - another one from last year):

Pale Brindled Beauty (male) Phigalia pilosaria - Dorset 14.1.25

Pale Brindled Beauty is distributed more widely than its darker namesake, but both species have suffered significant declines in abundance (83% and 78% respectively). One significant difference between the two species is that Pale Brindled Beauty females are flightless; the females have no wings and therefore have very limited mobility, a characteristic that is shared by a number of other early-flying species including the March Moth (see below). 

One of the most distinctive Spring geometrids is Early Thorn (below), pictured last month. The Thorns are some of the few UK moths that hold their wings vertically when resting.

Early Thorn Selenia dentaria - Dorset 23.2.26

There are eith UK Thorn species of which only two appear in the Spring months. Early Thorn is the most common and widespread, although it is even more frequent during its later second generation in July and August. The formal term for such double-brooded species is 'bivoltine'. The other Spring-flying species is the arguably more spectacular Purple Thorn (below); I don't see many of those here, so have had to dig into the archives for an image from 2022.

Purple Thorn Selenia tetralunaria - Dorset 16.4.22

The coloured banding on the underside of Purple Thorn's wings is strikingly different to that of Early Thorn. If you compare the two images you will see that small white crescent 'moons' can be seen on the underside of each of Purple Thorn's four wings (hence tetralunaria) while only two (on the hindwings) are seen on Early Thorn. (The much rarer Lunar Thorn also has four 'moons', but flies a bit later in the year.) But the key distinction is that Early Thorn is the only UK Thorn species that holds its wings pressed together; in Purple Thorn, and the others, a gap is maintained.

Very different in appearance from most other geometrids is the March Moth (below), which despite its name can appear as early as January. The first male of the year turned up here at the end of February, but this image is from one observed last year. Like the Pale Brindled Beauty (see above) the females of this species cannot fly.

March Moth male Alsophila aescularia - Dorset 23.2.25

Erebidae

All but one of the larger (macro-) moths that I have trapped this year belong to the two main families described above. The exception is the beautiful Herald (below), which I discovered sitting on a garden chair next to the moth trap this morning. Fortunately it had escaped the attention of the local Robin. 

Herald Scoliopteryx libatrix - Dorset 23.3.26

Claiming this as a Spring moth is a bit of a cheat, as the Herald flies during most months of the year. However, unlike all of the species described above, it overwinters as an adult, finding cover in a quiet location such as a natural cave or somebody's garden shed before emerging around March. Historical data shows that the average time of emergence has moved forward several weeks since the 1970s, yet another climate change-related effect.  

That concludes my brief run-through of the most commonly-seen Spring moths. Numbers of species, and of individual moths, will start to rise as the year progresses, so I doubt whether I can attempt another seasonal survey. But more moth blogs will be coming. In the meantime, happy mothing!

References

Identification references used are set out in more detail in a separate blog - link here.

Distribution and abundance information is from the excellent Atlas of Britain and Ireland's Larger Moths (Randle et al, 2019). 

  

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

 

Crossbills at Affpuddle

Common Crossbill male - Affpuddle Heath, Dorset UK 16.3.26

2026 is looking like being a good year for Crossbills here in Dorset, UK. The Common Crossbill is a scarce breeder in the county, but can occur in greater numbers during 'irruption' years. It's a species that I have had little luck with. Despite regular reports of the birds being present at a particular site near Affpuddle, three previous visits all drew blanks.  So I wasn't too hopeful about this morning's trip - but it turns out that my fortunes had changed.

Affpuddle forest - Crossbill country

Affpuddle Forest (strictly Affpuddle and Moreton Forest) sits on a low ridge separating the valleys of the Rivers Piddle and Frome in West Dorset. Formerly heathland, the area has been extensively planted with conifers, mostly Scots Pine. Several open areas remain, largely grassland dotted with Gorse bushes. Part of the land is managed by Forestry England, and has open access, while other areas are crossed by public footpaths and bridleways. Car parks are provided at Culpepper's Dish, a surprisingly large sinkhole of some geological interest, and on the B3390 south of Affpuddle village. 

I parked at the second of these and started walking eastwards towards Culpepper's Dish. It was about 0830 in the morning, and there was sporadic birdsong in the woodland: mostly Robins and Siskins along with a distant lone Yellowhammer. A small group of Long-tailed Tits flicked past.

Reaching the stand of trees pictured above I noticed some movement high in the canopy. Several birds were feeding on pine cones while others flew between the tree tops in small groups of two or three. Even at some distance I could see that they were Crossbills: rather chunkier than most other finches and showing flashes of red (males) and a dull yellow (females). Every now and again a larger movement would see ten or more birds flying to another tree. They were very mobile, but never went more than around 50 metres from my original sighting. 

It was a dull morning with a light drizzle, and the light wasn't great. I was resigned to only getting distant treetop views, when a small group flew down and sat obligingly in a smaller pine tree , dotted like Christmas decorations (below).

Common Crossbill group - Affpuddle Heath, Dorset UK 16.3.26

Even better, one male flew even closer and perched on the top of a leading shoot right next to the road (below). Despite the gloomy conditions, his brick-red colour stood out.  

Common Crossbill male - Affpuddle Heath, Dorset UK 16.3.26

The lack of cones on these smaller trees suggested that the birds had flown down to get a drink, so I  stationed myself at a respectful distance from a suitable puddle (below). There are no shortage of these at the moment; Dorset has had a memorably wet winter.

Crossbill refreshment opportunity

It worked - and I'd picked the right puddle. Around 15 Crossbills dropped down into a couple of Silver Birch trees next to the track, visible at first only as silhouttes (below).

Common Crossbills in Silver Birch

It wasn't long before they began to drop down for a quick drink. Both males ...

... and the rather less showy females:

All in all, I estimated that there were at least 20 individuals present, although there could have been more. I never saw the entire group at once. This is a good number: the most recent Dorset Bird Report (2024) lists 'significant counts' as being 10 individuals or over, and there are only three records of as many as 20 for that year. It looks likely that 2026 will be rather better - we shall wait and see.

Reference

Dorset Bird Report 2024 - Dorset Bird Club (published December 2025)

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