Ireland is notably one of the few places globally that does not have any native snake species, especially considering that neighboring Great Britain is home to several snake species. The absence of these reptiles in Ireland is a long-standing fact, supported by scientific evidence.
Geological and Climatic Explanations
The primary scientific reasons for Ireland’s lack of native snakes are deeply rooted in its geological history and subsequent climatic conditions. During the last Ice Age, which ended approximately 11,500 years ago, Ireland was largely covered by a thick ice sheet, making it uninhabitable for cold-blooded creatures like snakes, eradicating any pre-existing reptile populations.
As the ice retreated, sea levels rose, forming land bridges that allowed some species to migrate to newly exposed lands. A land bridge did exist between Great Britain and mainland Europe, allowing three snake species to colonize Britain. However, the land bridge connecting Ireland to Great Britain became submerged about 8,500 years ago, roughly 2,000 years before the land bridge to Britain disappeared. This timing meant that snakes, which are relatively slow dispersers, did not have enough time to cross into Ireland before it became an island.
Ireland’s current climate also plays a role in preventing snake colonization. Snakes are ectotherms, meaning they rely on external heat sources to regulate their body temperature. While some snake species can tolerate cooler temperatures, Ireland’s cool, wet climate is less hospitable for most snake species compared to warmer, drier regions. The lack of sufficient prolonged warmth makes it difficult for snakes to thrive and establish breeding populations.
The Myth of St. Patrick
A widely known cultural explanation for the absence of snakes in Ireland attributes it to Saint Patrick. According to legend, Saint Patrick banished all snakes from the island, driving them into the sea after they attacked him during a 40-day fast on a hillside.
However, this story is a myth or religious allegory, not a scientific explanation. Historians suggest the banishment of snakes symbolizes Saint Patrick’s role in converting the Irish people from pagan beliefs to Christianity. There is no scientific evidence that snakes ever inhabited Ireland.
Other Reptiles and Amphibians in Ireland
Despite the absence of native snakes, Ireland is home to other reptiles and amphibians. The common lizard (Zootoca vivipara) is Ireland’s only native terrestrial reptile. This species is found across the island in various habitats. Unlike many other lizards, the common lizard gives birth to live young, an adaptation thought to be beneficial in cooler climates.
Another reptile sometimes encountered in Ireland is the slow worm (Anguis fragilis). This legless lizard is often mistaken for a snake due to its appearance but is not native to Ireland. It is believed to have been introduced to the Burren region of County Clare in the 1970s. While non-native snakes are occasionally found, they do not establish wild, breeding populations due to the unsuitable climate.
Ireland also has several native amphibian species, including the common frog (Rana temporaria), the smooth newt (Lissotriton vulgaris), and the natterjack toad (Epidalea calamita). These amphibians thrive in Ireland’s wet environment. While pet snakes are not banned in Ireland, the climate prevents them from surviving long-term if released into the wild.