This week non-native species of land snail have been on my mind a lot, as I was analysing an archaeological asssemblage which contained some Cornu aspersum Müller 1774, a species usually described as having been introduced back in Roman times. Walking in Yeovil this morning, I spotted a shell I had not seen locally before. It was from the snail Hygromia cinctella Draparnaud 1801, another introduced species. The sources I consulted (Kerney and Cameron 1979, Davies 2008*) both agree that it first appeared in Devon around 1950, and Kerney and Cameron describe its distribution as “SE France, extending up the Rhône valley into Switzerland (Geneva basin); also near the Atlantic in SW France” (Kerney and Cameron 1979: 190-191)
Snails are, you will of course realise, rather slow movers, so how do these species come to be present in the UK, and spread once they get here? Passive dispersal is the most likely answer. In the case of H. cinctella, and the much older introduction C. aspersum, the snails have probably been unintentionally moved by humans, perhaps in soil or produce. Davies (2008: 16-17) lists a number of introductions to the British Isles since the Bronze Age.
Here are some more pictures of Yeovil’s alien snail. I shall be keeping a good eye out for more specimens.
Davies, P., 2008: Snails: Archaeology and Landscape Change (Oxford: Oxbow)
Kerney, M.P., and Cameron, R.A.D., 1979: A Field Guide to the Land Snails of Britain and North-West Europe. (London: Collins)
*this asterisk doesn’t refer to any special meaning, it’s just there to stop WordPress rendering 2008close parenthesis as 2008) !