Impact of beavers in Argentine and Chilean Patagonia

For more than seven decades, the beaver has had a strong impact on the forests of the beautiful Isla Grande de Tierra del Fuego between Argentina and Chile. Their activities have caused important changes in the ecosystem and altered the native flora and fauna.

Classified as exotic and invasive in Argentina, this species has wreaked havoc in other important ecosystems such as aquifers and peat bogs. These wetlands play a crucial role in storing carbon dioxide. This phenomenon of direct forest damage by this species is having a significant impact in both countries, with losses estimated at more than $100 million a year.

The introduction of the beaver in Tierra del Fuego

At the time news summaries were showing in cinemas, there was a show called Sucesos Argentinos. This provided an overview of the key events before the films started showing. In the 1930s, before the advent of television, the cinema was the only audiovisual medium that allowed access to information about political, sporting, economic and social events. It was an important way to record and share events of that time. In 1946, one of these reports introduced an innovation aimed at “enriching the fauna of Tierra del Fuego,” as the off-screen narration puts it. The images captured the moment the first 20 beavers were introduced to Argentina, particularly in the remote and lonely latitudes of Tierra del Fuego.

The social imagination of the time viewed the Northern Hemisphere’s development model as more valuable and viewed the introduction of species from there as an opportunity for economic growthexplains Christopher Anderson, a biologist with a PhD in ecology and an associate professor at the National University of Tierra del Fuego.

Patagonia has been colonized on both the east and west sides of the Andes with various species of animals previously unknown in the region. Among them are the beaver, the American mink and the muskrat. These launches were aimed at commercializing their skins. “It would be unfair to judge those who made these decisions. There have not been enough studies to understand what might happen in the future“, explains Alejandro Valenzuela, a bioecologist specializing in the management of invasive species and associate researcher at the National Council for Scientific and Technical Research (Conicet).

Unimaginable effects of the beaver

In the past nobody could have imagined that a beaver existed (Castor canadensis), a rodent native to the forests of the United States and Canada, would be considered a pest in the southernmost archipelago of the Americas. However, the situation has changed and their eradication is now considered necessary.

In Argentina, an official statement was issued in 2014, classifying the beaver species as exotic and invasive. However, the province of Tierra del Fuego had already taken legal action since 2006 because it classified it as “harmful and harmful”. In Chile, on the other hand, since 1992, beavers have been found to be “harmful.”

In general, island ecosystems tend to be simpler and less resilient. That is, they are less adaptable to a perturbation that may cause, say, a volcanic explosion, human activity, or an exotic species.“, explains Valenzuela and continues: “The same applies to cold areas, since the number of native species is lower there than in tropical regions. Tierra del Fuego has both characteristics: It is an island in a sub-Antarctic region. A “new guest” has much higher chances of success than in similar ecosystems (continental level)

absence of predators

Being in an environment devoid of natural predators and alien to their kind for thousands of years, beavers have experienced rapid growth without encountering any resistance. It is currently estimated that the absolute number of invasions varies between 100,000 and 150,000. More importantly, however, is the realization that this invasion affects all watersheds in their entirety. We can already see the impact of this situation. Initially, the colonists occupied the entire Big Island of the archipelago. They then extended their dominion to the smaller islands and have even settled in the southernmost parts of the South American continent since the 1980s.

“In Tierra del Fuego the border is a fence, there is no physical barrier between countries. We share several watersheds and the beaver crossed from Argentina to Chile without a passportwarns Cristóbal Arredondo, coordinator of the land protection program in Wildlife Conservation Society (WCS) in Chile.

The beaver invasion process was gradual and not impossible to stop. In the north, bears, wolves and eagles play important roles in limiting beaver population growth. However, there are no predators in the south, which contributes to the glaring failure of the economic development project.

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