Some weeks ago I received an e-mail from Darren Naish; it was brief and to the point, and said that someone had just left a comment on his blog posting about green lizards, which read: "Hi - We have just found what we realised was a green lizard (half its tail missing) in our hall in Dorchester. Perhaps our cat brought it in - it ran out to the front garden, which has shingle and shrub cover. Both of us were pretty surprised - does anyone know of green lizards in Dorchester?"
It is just the latest event in a long, and tortuous saga, which was partially my fault in the first place. As I am sure every British reader of this bloggo will know, there are only three species of lizard known in these islands; the sand lizard, the common lizard and the slow-worm. However for nearly two hundred years now there have been reports of bright green lizards, considerably larger than any of the native species, which have been reported along the coast of East Devon and parts of Dorset. These animals are not just known from anecdotal reports but have been described in such august journals as the zoological society report from the Devonshire Association.
The scientific luminaries of the 19th Century were convinced that there was in fact a relic population of a fourth species of lizard living on the south coast of England, but after about 1920 everyone forgot about it until I rediscovered the old scientific papers a few years ago in a museum basement! After having investigated these reports for a number of years it seems (although I cannot prove it) that I am now pretty sure about what these creatures are.
There is a large and beautiful lacertid called the Western green lizard (Lacerta bilineata) which is found across much of Europe and is even found in the Channel Islands. Until very recently there was a thriving trade between the Channel Islands and the Dorset port of Weymouth (where boatloads of tomatoes and other delicacies were often unloaded before being transported into the hinterland for sale). I am sure that it is not a coincidence that when one plots the sightings of these green lizards over the years on a distribution map that Weymouth proves to be the epicentre. This suggests that over a period of perhaps two hundred years Lacerta bilineata as been an unwary stowaway to this country inside baskets of fruit and vegetables. Upon disembarking on the UK mainland they have spread into the surrounding areas where they have become established, and may even have bred.
Darren takes up the story:
On the basis of these historical records, Jon Downes (1994) proposed that viable feral colonies of green lizards existed in Devon and Dorset, and that they were probably introduced from either France or the Channel Islands. He became disappointed that his idea was ‘ignored by the zoological establishment’ and that ‘two famous zoologists (who shall remain nameless) told us that the theory was arrant nonsense. The paper was returned with a brusque letter from several zoological magazines and after a while we just gave up’ (Downes 2003, p. 13). Given that, as noted above, relatively long-lived feral colonies had been reported earlier from the Isle of Wight, however, it would seem likely that Jon was right.
The presence of what appears to be a viable, breeding colony, this time at Bournemouth, led Jon (Downes 2003) to write an article titled ‘Told u so’ [sic]. However, because there’s no evidence that the Bournemouth colony is anything to do with the historical Devon and Dorset records discussed by Jon, it’s not entirely satisfactory to claim that his contention has been vindicated. Then again, the fact that the Bournemouth colony is apparently viable and spreading (breeding is thought to have occurred) suggests that other colonies in southern England may well have been capable of this too. The Bournemouth colony was discovered by herpetologist Chris Gleed-Owen of the Herpetological Conservation Trust when he was on his way to work one day, and the colony is located just a few hundred metres away from Gleed-Owen’s office (Gleed-Owen 2004).
Why are the lizards there? Gleed-Owen has suggested that they are dumped pets that have since bred. Could they have been introduced accidentally from the Channel Islands, or the continent, as Jon suggested for the other possible colonies? To answer this you’d need to know what sort of imports Bournemouth receives from abroad, and I haven’t bothered to check that out. Finally, could they be late-surviving, hitherto-overlooked natives? This possibility has been inspired by the recent discovery that the (now extinct) British Pool frogs Rana lessonae of Norfolk and Cambridgeshire were almost certainly natives, and not continental introductions as usually thought. It’s also now being suggested that the European tree frog Hyla arborea colonies of the New Forest are also natives. Gleed-Owen regards the possibility of native status for the Bournemouth lizards as ‘unlikely, but not impossible’.
Leaving aside the mildly embarrassing reminder, that a few years ago I didn't suffer fools as gladly as I do now, and I was much more pugnacious and combative in my professional outlook than I have been since, I would suggest that the discovery of a specimen inland in Dorset; in Dorchester, does up the ante a little bit for those who either support my earlier theory that these lizards have been here much longer than just as a result of being 'dumped' exotic pets, or those who support the theory that Gleed-Owen describes as 'unlikely, but not impossible', that they are actually hitherto unsuspected natives.
Darren's article on the species can be found in the original version of Tetrapod Zoology: