The real reason there are no snakes in Ireland
It wasn’t Saint Patrick but a long history of chilly weather and geographic isolation that kept the Emerald Isle snake-free
Lanmas/Alamy; Illustration composite by Scientific American
When revellers flood Dublin’s streets for St. Patrick’s Day, one group is conspicuously absent: snakes.
Saint Patrick, known for spreading Christianity in Ireland, is also famed in folklore for driving snakes from the island using a crozier, a kind of ornate shepherd’s crook.
Ireland, a sanctuary for those afraid of snakes, has no native snake species. This absence of snakes predates Saint Patrick by a significant margin. Fossils suggest wild snakes and many other reptiles never inhabited the island.
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“We really only have two reptiles,” says Collie Ennis, a science officer at the Herpetological Society of Ireland and biodiversity officer at Trinity College Dublin. “We’ve got one native land reptile—that’s the common lizard…. We also have an introduced reptile in Ireland called the slow worm, and it’s a type of legless lizard.”
Most scientists believe that Ireland’s lack of reptiles is due to the last ice age, which ended about 11,700 years ago. As the glacial ice melted and the climate warmed, Ireland had already separated from the European continent, making it inaccessible to reptiles.
Today, Ireland remains too cold for most snakes. Reptiles, unlike mammals, cannot regulate their body temperature internally, preferring warmer climates between 70 and 100 degrees Fahrenheit (21 and 38 degrees Celsius). Prolonged cold can immobilize or kill them. However, Ireland’s native common lizard (Zootoca vivipara) and the introduced slow worm (Anguis fragilis) are resilient, capable of hibernating through winter.
Cold climates and geographical isolation have prevented snakes from thriving on many islands, including New Zealand, Iceland, and Greenland.
Nevertheless, snakes can still be found in Ireland, albeit not in the wild. Facilities like Dublin Zoo and the National Reptile Zoo in Kilkenny house various snake species, attracting numerous visitors. Among pet owners, snakes are increasingly popular, reflecting a growing interest in reptiles.
“In my lifetime, we went from where the only time you’d see a snake in Ireland would be in the actual zoo … to many people of all ages keeping them as pets,” Ennis says. “I think they’re one of the favorite pets we have in the country at this point in time, so there is a huge interest in reptiles.”
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