Leave it to Beavers

Forget guns, germs and steel, Canadian beavers have colonized Tierra del Fuego and Isla Navarino using only buck teeth and broad tails.

It all goes back to the 1940s, when Argentina's hapless military government imported 25 pairs of beavers from Canada, hoping they would multiply and generate a lucrative fur industry in this largely undeveloped area. Without natural predators, the beavers did multiply, but since felted beaver hats lost their fashion appeal the industry collapsed.

Today around 150,000 beavers inhabit Tierra del Fuego and the surrounding islands, where they are officially considered a plague. Beavers' damaging effects are many. Argentina estimates that they have built around 70,000 dams. Flooding from beaver dams destroys roads and meadows, ruining infrastructure and creating havoc for livestock. Loggers compete with the rodents for wood, and risk losing their livelihoods. A sole beaver couple has the chewing power to create their own lake, felling hundreds of trees. Beavers can also pass giardia into water supplies where it works its black magic on human intestines.

Busy beavers have already made their way across the Strait of Magellan from where they could spread to the rest of the South American continent. With the help of global grants, conservationists, scientists and forestry officials are in a rush to eradicate populations, at an estimated cost of US$35 billion. Only then will reforestation be feasible.

Following a young scientist couple who have made the beavers their life mission, the Chilean documentary Los Castores debuted to acclaim in Chilean film festivals in 2014; it's now available for viewing online.