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).
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| 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.
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| 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.
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| 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).
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| 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.
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