PUERTO WILLIAMS, Chile – The proliferation of beavers and minks at Chile’s southern tip – a legacy of a failed attempt to establish a fur industry – threatens biodiversity in one of the world’s most pristine corners, ecologist Ramiro Crego told Efe.
Both species, neither of them native to the Southern Hemisphere, were introduced in Tierra del Fuego in the mid-20th century.
Some animals escaped and others were released from derelict breeding farms and have become “a devastating plague” for the environment, according to Crego, a doctoral student in biology at the University of North Texas.
“In 1946 Argentine entrepreneurs released about 50 Canadian beavers in Tierra del Fuego and for more than three decades it was prohibited to hunt them,” Crego said. “Beavers change the habitat to create conditions adequate to their survival. With tree trunks and branches they build dams in rivers.”
The beavers’ activity causes extended floods in the forests around the rivers, as the trees are not adapted to such conditions, and wide areas become meadows dotted with the gray skeletons of dead trees.
“The problem has spread to all of Tierra del Fuego and the Cape Horn archipelago,” Crego said.
Several attempts have been made to eradicate beavers, destroying their dams with explosives and laying down traps in rivers, but all efforts have failed because “they are a very dynamic species and they are hard to catch,” said Crego, adding that it can take up to two weeks to track down a beaver.
The North American mink, introduced to the region in 1934, now threatens different species of birds and small mammals particularly on Navarino Island, where minks have no natural predators.
“The problem with this island is that, before the introduction of this invasive species, there were not many mammals, and there were not many fish in rivers, fish being the main fare for minks,” Crego explained.
Birds, who in the absence of natural predators have always laid their eggs on the ground, have become the main prey for the intruders.
“In the long term, if beavers and minks are not eradicated, there will be a loss of species and a very different ecosystem will be created,” Crego said.