Binational Beaver Control Programme — Tierra del Fuego (Argentina–Chile)

In 1946 the Argentine Navy introduced about 20 North American beavers (Castor canadensis) to Isla Grande, Tierra del Fuego, to start a fur trade. With no natural predators, the population has since grown to an estimated 65,000-150,000 animals across the Argentine and Chilean sides of the island, and beaver dams have altered roughly 31,000 hectares of peat bogs, forest and grassland, damaging about 40,000 hectares of native Nothofagus forest, with some 16 million hectares of forest considered at risk.

Argentina and Chile signed a binational management agreement in 2008, later securing GEF/FAO funding for coordinated control efforts aimed at reducing the invasive beaver population and the damage it causes to native forest and peatland ecosystems.

Argentina's pilot programme (2016-2018) trapped and removed more than 1,000 beavers across 505 colonies in seven test areas covering roughly 180,000 hectares. Chile's parallel Proyecto GEF Castor (2017-2022) built national control capacity, building on an earlier 2005-2006 campaign that had already removed 11,700 beavers.

The economic case for control is significant: Argentine officials estimate beaver damage costs around $66 million a year, and Chile put its 2020 damage at roughly $73 million. Feasibility studies diverge on the cost of full eradication, citing figures from $15 million over 15 years to $31-33 million over 17-30 years, reflecting real scientific and financial uncertainty rather than a settled plan.

Implementation has stalled since 2018, with project participants themselves acknowledging that 'practically nothing' has been done at scale since then, largely for lack of sustained political commitment across two governments over multiple decades. A 2021 peer-reviewed study also complicated the simple 'pest' narrative, finding that beaver ponds locally increase bird diversity — a genuine ecological trade-off rather than proof the programme should stop.