Why Aren’t There Snakes in Ireland?

The island of Ireland is one of only a few places in the world where there are no native snakes- alongside places like Greenland and Antarctica.  But Ireland’s climate is nowhere near as harsh as these icy places, so why aren’t there any snakes?

County Clare, Ireland.

 In Christian and Irish tradition, the absence of snakes can be blamed on St. Patrick, the patron saint of Ireland.  He is said to have chased all of the snakes into the sea and banished them from Ireland as he converted the Irish people from paganism. In reality, the reason there aren’t snakes in Ireland is not quite as dramatic and fantastical. According to the fossil record, there is no evidence that there have ever been any snakes in Ireland, certainly not enough for St. Patrick to chase out the slithering serpents. 

But that still leaves the mystery of why snakes never populated the island. Well, scientists believe that this is due to the most recent glacial period, the ice age, which ended approximately 11,500 years ago. At this time, Ireland would have been an icy, cold tundra, uninhabitable for creatures like snakes.


When this ice melted, bringing on our current Holocene period, many islands had land bridges that allowed species to cross and populate. Ireland however, did not have a land bridge at the time the Holocene period came around, and so only those animals that could cross the icy sea before it melted and quickly occupy the land were able to settle in Ireland. While not quite as sensational as the tale of St. Patrick, this is why there aren’t any snakes in Ireland!

It’s true that snakes were unable to make the journey across the Celtic Sea, but many other species were. Animals such as the red fox, the viviparous lizard, and the lynx (although now extinct on the island) crossed the ice bridge between Ireland and England!


  1. Snakeless in Ireland: Blame Ice Age, Not St. Patrick. 2018 Aug 16. Animals. [accessed 2023 Mar 15]. https://www.nationalgeographic.com/animals/article/snakeless-in-ireland-blame-ice-age-not-st-patrick?loggedin=true&rnd=1678886120301.
  2. NOAA. 2021. Glacial-Interglacial Cycles. https://www.ncei.noaa.gov/sites/default/files/2021-11/1%20Glacial-Interglacial%20Cycles-Final-OCT%202021.pdf.
  3. Could reintroducing the lynx solve Ireland’s sika deer problem? The Irish Times. [accessed 2023 Mar 17]. https://www.irishtimes.com/environment/2022/06/16/could-reintroducing-the-lynx-solve-irelands-sika-deer-problem/.
  4. Pygmy shrew – The Vincent Wildlife Trust. [accessed 2023 Mar 17]. https://www.vincentwildlife.ie/species/pygmy-shrew#:~:text=They%20have%20poor%20eyesight%2C%20which.
  5. O’Connor R. Delight as rare wild boars born in Ireland during lockdown. The Irish Post. [accessed 2023 Mar 17]. https://www.irishpost.com/news/delight-baby-wild-boars-born-ireland-first-time-800-years-184738.

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