Monday, March 18, 2013

A Snake for St. Patrick

According to legend, Saint Patrick is responsible for the lack of snakes in Ireland.  He is said to have chased them into the sea for attacking him while he was undertaking a 40 day fast.  To this day Ireland has no snakes.

The science of why Ireland has no snakes has nothing to do with Saint Patrick or any other saint.  Ireland's lack of snakes can be attributed to ice.  Ireland was covered with glaciers during more than one ice age.  The most recent ice age, which ended about 11,000 years ago covered over three quarters of the island with ice.  The remainder of Ireland was too cold for snakes.

During this last glacial period, a land bridge connected Ireland with the rest of Europe, allowing some species to populate Ireland, but snakes were not among them.  When the glaciers melted the sea levels rose, covering the land bridge, leaving Ireland without snakes.

Here in Mid-Michigan, we are lucky that the snakes were able to return after the glaciers receded.  They play an important role in our ecosystem as an effective predator of many small animals.  They in turn are preyed upon by many birds and mammals.

So in honor of yesterday's St. Patrick's Day celebrations,  I give you a snake.

Common Garter Snake (Thamnophis sirtalis)

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