I have recently been searching for the Glanville Fritillary (Melitaea cinxia) and have made several visits to a number of mainland sites, both traditional, and others of more recent establishment.
I, and indeed many others, have been aware for some time of the presence of an unofficial introduction site for M. cinxia in Surrey. This particular colony appears to have survived well in the conditions provided by the location, which in many ways are similar to the undercliff environments found on the Isle of Wight and at the nearby mainland area at Hordle Cliff. Although sand extraction continued over a period of approximately fifty years until 1993, the site currently lies quiet and is filled with an abundance of both aquatic and terrestrial flora and fauna. Landfilling of the eastern sector of the site ceased in 1990. A further unauthorised site, at Sand Point in Somerset, probably died out in around 2000 after their introduction in 1983, but this would appear to have been restocked, or the butterfly having survived in very low numbers, as M. cinxia has been recorded there in 2012.
So, should they be in Surrey?
Historically, M. cinxia has shown a substantial reduction in its range, surviving in any real numbers at traditional locations only on the southern shores of the Isle of Wight, with occasional reports from the nearby mainland. As recently as 1943 it could readily be found at Christchurch in Hampshire and at several places along the Kent and Sussex coast before 1850. With less certainty, it has been recorded from inland localities in Yorkshire, Lincolnshire, Northamptonshire, Wiltshire and Bedfordshire, and even from Fifeshire in Scotland. The Surrey M. cinxia colony, currently in its 10th year, was originally established from 300 larvae from three batches of wild collected webs, which originated from Whale Chine on the Isle of Wight. After release, no adults were seen for 3 years. However, during a cursory inspection of the site, whilst considering the release of their captive cousins as post hibernation larvae, the originator of the colony discovered 39 larval webs. It has been reported that in 2010 the population was huge, with plenty of larval webs covering the site, though numbers dropped in late August of the same year due to the very wet conditions which prevailed. The winter and spring of 2011 looked very poor though the adults emerged and made a good show. Though numbers are generally being reported as low this season, compared to the high of 2010, reports would suggest they are holding their own.
So to answer my question, should they be in Surrey?
I think the simple answer is probably not though there are numerous arguments that could be made for and against such an introduction, including the personal short term satisfaction they give to the onlooker, including myself, though I feel this view may be overlooking the bigger long term conservation picture. I personally don't have a particular problem with re-introducing M. cinxia on the mainland 'providing such releases are approved and backed by appropriate knowledge, research and monitoring', given that a couple of hundred years ago they were found as far north as Lincolnshire. Man has, after all, been responsible for the extermination of many species, never mind colonies, so any efforts to redress the balance is surely to be encouraged.
Others will undoubtedly have a different opinion …
