Reclassifying grass snakes

 The UK has three species of snake, the adder (Vipera berus), the smooth snake (Coronella austriaca) and the grass snake, recently re-classified as Natrix helvetica.

We had thought that there were only two species of grass snakes: Natrix natrix, native to most of Europe, including the UK, and Natrix asteptophora, found in north Africa and the Iberian Peninsula. Natrix natrix was divided into fourteen subspecies and grass snakes in western Europe (including in the UK) were of the subspecies Natrix natrix helvetica.

From the left: adder, smooth snake and grass snake

But a 2017 genetic analysis of European grass snakes suggested that Natrix natrix helvetica was sufficiently different from the grass snakes of central Europe to be considered a separate species and should be reclassified as Natrix helvetica.

Unfortunately there isn’t a Speciation Committee that will consider your research and rule on your findings; science doesn’t work like that. Instead, you publish your findings, suggest that a subspecies should be considered a separate species and then you wait while your fellow experts discuss. Some will agree with you and begin to use the new nomenclature while others will disagree and continue to use the old classification.

Grass snakes photographed in the reserve

This means that there was a period of time while our native grass snakes were classified in two different ways, neither of which was actually wrong or right. All kinds of misunderstandings ensued and some media outlets just got it plain wrong. The BBC, for instance, announced that a fourth species of snake had been found in the UK and then, to really confuse matters, a new common name popped out of nowhere: the barred grass snake. Our native grass snakes (N. helvetica) are sometimes being referred to as barred grass snakes to distinguish them from the common grass snake (N. natrix) which is native to central Europe. Are you confused yet? So are we.

Over a period of years, a consensus has been reached and most authorities are now happy to use the new binomial Natrix helvetica. There is no fourth species of British snake; our grass snakes, whether or not you call them barred grass snakes, have just been renamed.