15 March 2013

Year of the Snake: Snake Tails

To celebrate the Chinese Year of the Snake in 2013 we are collecting interesting facts, research and stories about these often maligned or misunderstood animals.  Here Froglife’s Public Engagement Officer Sivi Sivanesan looks at snakes in the Emerald Isle in preparation for St Patrick's Day on Sunday.

“St Patrick was born in Britain in the 5th century (circa 390-461 AD) and one of his miracles includes driving snakes out of Ireland, part of his status as their Patron Saint.  In fact this miracle appears to be an 11th century addition to his 7th century biography, and a reminder of the persecution of snakes due to their links with the devil in Christianity and Catholicism.

From a scientific point of view, there is an interesting question here - why aren’t there snakes in Ireland? 

A grass snakes swimming
There are three species of snake in England, with two seen in the colder climes of Scotland.  The animals are widely believed to have never made it to the landmass that became Ireland due to the impact of a combination of ice ages.  This resulted in initial barriers to snake migrations, with subsequent rising sea levels stopping the few species that made it to mainland Britain accessing Ireland.

While many snake species can swim, and both adders and grass snakes have been spotted swimming off the east coast of England in the past, potentially the distance and local currents in the Irish seas may have proven too much of an obstacle for local species to have overcome.

If snake populations ever do make it back into Ireland, it would likely be the result of escaped animals from the pet trade or collections; or even deliberate introductions to habitats that could support them. 

However, there are lizards in Ireland. The common lizard Lacerta vivipara is the only lizard to have made it to Ireland. The mechanisms of its route are still being studied but L.vivipara is the widest distributed lizard in the northern hemisphere (found as far north as the Arctic Circle and as far south as Spain). Its ability to exploit a wide range of climatic ranges may explain how it was able to colonise Ireland when land bridges still existed during ice ages;  when grass snakes and adders couldn’t."
Photo: Tony Wharton