North American Beavers in South American Forests?

Geography in the News is an educational series offered by the American Association of Geographers for teachers and students in all subjects. We include vocabulary, discussion, and assignment ideas at the end of each article. 

By Cadence Bowen

Patagonia, a remote region at the tip of South America, has some long-distance intruders. In 1946 the North American beaver (Castor canadensis), was brought here. Its population has thrived—to the dismay of local humans.

The story of beavers in Patagonia shows how humans can introduce invasive species. These are non-native species which can overrun native species. This often causes an imbalance in the ecosystems in these environments. The problem of invasive species is driven by human interests, such as commercial or agricultural use of animals or plants.

North American beavers were almost wiped out in their native habitats by 1900. They were saved through intense conservation. Ironically, in Patagonia the focus is how to get rid of them. The Wildlife Society’s Pablo Jusim says, “Technically, it’s viable to eradicate beavers from South America—one of the biggest eradications in the world if we achieve it.” He estimates a cost of about $31 million and 20 to 30 years to eliminate Patagonian beavers and restore ecological balance.

Well, How Did They Get Here?

Imagine the southernmost part of South America: that’s Patagonia. Part of both Chile and Argentina, Patagonia is known for its diverse geography. Snowy mountains and lush forests in the west are answered by steppes and deserts in the east. The archipelago of Tierra del Fuego is at the tip of this area. It has its own diverse and rugged terrain, from lowlands and glaciated coasts in its north to high mountains in the east.

In 1946, the Argentine government introduced just 20 North American beavers to Tierra del Fuego. The intention was to kickstart a fur trade for pelts. Officials believed the climate would be similar enough to the beavers’ native climate to suit them. Little thought was given to native trees, plants, and ecosystems. The trees and forests of North America co-evolved with beavers and can take their energetic tree felling and dam building. The native forests of Tierra del Fuego had never experienced anything like this. Plus, beavers have no natural predators in Tierra del Fuego. Eighty years later, the species’ population is more than 150,000, almost outnumbering human inhabitants.

Impacts of these “Ecosystem Engineers”

Beavers are ingenious animals with the ability to alter the landscapes they inhabit. These furry creatures are admired for their important roles in North America, both their contributions to river ecologies, and their earlier pivotal role in the fur trade of early America. They shape the environment more than any other species besides humans. Kodi Jo Jaspers, manager of the Wenatchee Beaver Project in Washington State, calls them “ecosystem engineers.”

When beavers build dams in North America, they create habitat for a lot of different species. This can help address the impacts of climate change by retaining groundwater, absorbing rain, and stopping or slowing the spread of wildfires.

Beavers’ impacts in North American ecosystems don’t translate well to the South American islands of Tierra del Fuego. They have become destructive toward its pristine forests and rivers. They lack the natural predators that North American beavers face, such as bears, wolves, and coyotes. Their natural behavior—gnawing trees and building dams—causes the roots of the remaining trees to rot in the saturated soil. Eventually, these trees to die. The river systems and watersheds that support life on the islands are filled with dead flora and sediment.

“I admire the animal actually. … How it works with the rivers, how it is adapted, how they molded nature for their own benefit, builds his house, his dams. ”

—Pablo Kunzle, Interviewee in Beavers: Patagonia Invaders

Is there a future Patagonia without beavers?

The 2015 documentary, Patagonia Invaders, highlights the community response to Tierra del Fuego’s beavers. From trendy fur coats to beaver tenderloins, locals have taken unusual steps to reduce the numbers of these invasive critters and their continuing impacts.

A study in the 1990s showed they had colonized about 94% of the rivers in the archipelago. Peacefull population control measures had limited results. In 2015, the Argentine government began a three-year eradication project. They applied the toughest means: full-body traps and hunting. The approach was successful enough for The Wildlife Society to recommend a larger-scale approach.

Researcher Mara Dicenta coined the term “Beavercene” to describe the changed landscape of Tierra del Fuego since 1946. She views the introduction and attempted eradication of beavers there as two ends of the same spectrum, caused by “a history of colonial interventions that ignore local environments.”

The latest approach to managing beavers in Tierra del Fuego’s forests might result in harmony or further destruction. In a fragile place that is out of balance, that question still hangs in the balance.

And that is Geography in the News, updated October 10, 2025

Material in this article comes from “North American Beavers Destroy South American Habitat” (2008), an original article for Geography in the News by Neal Lineback and Mandy Lineback Gritzner. 

AAG’s Geography in the News is inspired by the series of the same name founded by Neal Lineback, professor and the chair of Appalachian State University’s Department of Geography and Planning. For nearly 30 years from 1986 to 2013, GITN delivered timely  explainer articles to educators and students, relevant to topics in the news. Many of these were published on Maps.com’s educational platforms and in National Geographic’s blogs. AAG is pleased to carry on the series.

Sources Consulted for this Article

• Dicenta, M. (2020). The Beavercene: Eradication and settler-colonialism in Tierra del Fuego. Environment and Society Portal, Arcadia Collection, Spring, (1) https://www.environmentandsociety.org/arcadia/beavercene-eradication-and-settler-colonialism-tierra-del-fuego
• Jusim, P., A.P. Goijman, A. Schiavini (2025). A leap in scale for invasive species management: a medium-scale beaver eradication pilot project. Wildlife Management 89 (3), April. https://doi.org/10.1002/jwmg.22706
• National Wildlife Federation Invasive Species (Threats to Wildlife Guide). n.d, https://www.nwf.org/Educational-Resources/Wildlife-Guide/Threats-to-Wildlife/Invasive-Species
• Ogden, L. (2018). The beaver diaspora: A thought experiment.” Environmental Humanities 10 (1): 63–85. https://doi.org/10.1215/22011919-4385471
• Rapp Learn, J. (2025). The Wildlife Society Wild Cam: How feasible is beaver eradication in Argentina? https://wildlife.org/wild-cam-how-feasible-is-beaver-eradication-in-argentina/
• S. Fish & Wildlife Service, Invasive Species Program (n.d). https://www.fws.gov/program/invasive-species
• S. Fish & Wildlife Service. (n.d.). Beavers work to improve habitat. https://www.fws.gov/story/beavers-work-improve-habitat
• YouTube Movies & TV. Beavers: Patagonia Invaders (2015). https://www.youtube.com/watch?v=3F_wWA7KiTg&t=3s

Vocabulary and Terms

• Archipelago: A group of islands scattered across a body of water
• Co-evolve: When two or more species have evolved together over millions of years, and have influenced or supported each other’s evolution
• Ecosystem: A place that is defined and shaped by the relationships and interactions of many species within it.
• Flora: Broad definition for plant life
• Habitat: The place where life forms live; the habitat is made up of the conditions and features of the land, as well as the habits and relationships of species living there.
• Nonnative Species: Living beings that are removed from their original natural environments and introduced to another by humans
• Invasive Species: Nonnative species that have traits which enable them to outcompete and threaten native species, or cause damage to habitats..
• Steppes: A large area of flat, unforested grassland
• Terraform: To transform an area of land, often with removal of material, new structures, or addition of non-native species of plants and animals that can change the habitat.
• Watershed: A geographical area that channels precipitation to rivers, streams, or creeks to eventually reach a larger body of water, such as bays or the ocean

Questions for Discussion and Further Study

1. What are invasive species? What is the most common way for invasive species to be introduced?
2. When we talk about species that have co-evolved, are we only talking about native species?
3. Why were North American beavers introduced to Tierra del Fuego? What was the result of this introduction?
4. Why do North American beavers thrive in Patagonia?
5. Can you think of any invasive species in your local environment? What efforts are being made to control or eradicate the species?