Wednesday, March 14, 2012

Eager Beavers

Beaver Pond- Wikimedia
I don't know what the world's worst invasive species is, but the North American beaver certainly has to be in the running for the title.  While most of our problems come across the ocean from the east or west, the invasive beavers are located about as far south as you can go on land.

Twenty-five pairs of our common beavers, Castor canadensis, were brought to Tierra Del Fuego Island at the tip of South America in 1946.  Like most foreign species introductions, it seemed like a good idea at the time.  The idea was to create a commercial fur industry in an area with lots of trees and water and no significant beaver predators.  That should have been the first clue.

The beaver took a liking to their new surroundings and the southern beech, Nothofagus pumilio, forests.  They then expanded on to the steppes and finally crossed over to the Chilean mainland by 1990.  They had found their idea of heaven and reproduced like eager beavers will.

They have taken over 15-30% of stream length and occupy vast areas of the landscape.  The riparian areas are now virtually leveled and the possibility of completely eradicating the beaver population are the same as we face in eliminating kudzu.

A map of the area is available at this National Geographic site.

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