ANIMALS Why Doesn’t Ireland Have Snakes?

GREEN SNAKE

Care_SMC, via Flickr/CC BY ND 2.0

Legend has it that, back in the fifth century A.D., St. Patrick exterminated Ireland’s snakes by driving them into the sea. He would appear to have done a thorough job, because Ireland is free of native snakes to this day.

Except, Ireland never actually had snakes. Everything you’ve been told about St. Patrick's Day is a lie. (Ok, probably not all of it.)

So, if snakes can be found almost everywhere else the world, from Australia to the Arctic Circle, what makes Ireland so special?



WHERE SNAKES LIVE
For one, it’s an island. The Irish Sea is 50-plus miles wide. That would be a long swim for a land animal. A sea snake might have an easier time of it, but sea snakes live in warm tropical waters, not the frigid Atlantic.
But, you may be thinking, the U.K. has snakes, and it’s an island. That’s true. But for a long time, neither Britain nor Ireland was home to snakes. The Ice Age made the islands inhospitable to reptiles, whose cold-blooded bodies need heat from the surroundings to function. The glaciers retreated around 10,000 years ago, exposing a land bridge between Europe and Britain, and another between Britain and Ireland, allowing easy passage to the islands. Melting glaciers drowned Ireland’s land bridge 8,500 years ago, whereas Britain’s persisted for another 2,000 years. So animals from Europe simply had more time to colonize the U.K., and even then only three snake species managed to establish themselves in Britain. None of the three appears to have felt compelled to keep moving west toward Ireland; there's no evidence for the slithering reptiles in Ireland's fossil record.
ST. PATRICK STEPS ON A SNAKE
Andreas Franz Borchert via Flickr CC By SA 2.0
Other islands that don’t have snakes include New Zealand, Hawaii, Greenland, Iceland, and Antarctica. Still, the absence of snakes does seem somewhat miraculous, given the global pet trade and the serpents’ potential to becomeinvasive.
Read More at:
https://www.popsci.com/why-doesnt-ireland-have-snakes#page-2

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