Argentina brought beavers to Tierra del Fuego. It was not a good idea.

This beaver burrow is in an area of peatlands in Tierra del Fuego. Beavers create their dens by burrowing into the banks of rivers, lakes, and ponds. They begin by boring an entrance hole under water and continue digging at an upwards angle until they have hollowed out a living space above the water level. If they encounter banks that are too shallow to excavate, they build dams using felled trees and branches.

Arturo Forestello, 27, is one of ten “restorers” hired by the Argentine government to hunt beavers as part of its pilot studies.

A local beaver hunter holds up a pelt that has been salted, dried, and nailed to a piece of wood to prepare it for sale. The demand for such furs is limited; prices per pelt hover around $10.

Since 2008, Argentina and Chile have agreed that to save their southernmost forests, they must rid them of beavers. Some hunters working to eradicate beavers use snares in addition to rifles. But beavers are smart—they sometimes use weeds and sticks to trigger the snares without getting caught themselves.

Hunters use this oily castor-based spread to lure beavers out of their dwellings. Castor is a pungent substance beavers secrete to mark their territory.

Julio Escobar, a researcher at the Austral Center for Scientific Research (CADIC) who is working on Argentina’s eradication study, surveys an area of the Tierra Mayor Valley that was cleared of beavers.

This pond in the Tierra Mayor Valley, outside Ushuaia, was cleared of beavers as part of the Argentine government’s eradication project. Ponds created by beaver dams attract muskrats, another invasive species in Patagonia. Muskrats are in turn hunted by minks, creatures that also prey on native geese, ducks, and small rodents.

Erio Curto, the director of Fauna and Biodiversity for Tierra del Fuego’s environment ministry, works with Julio Escobar and several other researchers on Argentina’s beaver eradication plan. He lives in Ushuaia, where beavers have previously gnawed through fibre optic cables, leaving the city without internet or cellular service.

Guillermo Deferrari, a scientist at CADIC, has studied beavers since the 1980s. He is currently researching whether the size of beavers’ heads and bodies is dependent on the type of environment they inhabit. (The label on his lab coat, which translates to “Dr. Death,” is a joke among the scientists and is unrelated to his work with beavers.)

This skull is from a beaver killed as part of Argentina’s eradication pilot project. Beavers have high levels of iron in their tooth enamel, which gives their incisors strength and a vibrant orange hue. Beavers’ teeth grow continuously, so they are never worn down by their tireless gnawing.

Trees in North America have evolved over millions of years to withstand beavers’ energetic gnawing. Beavers are a much more recent addition to the South American ecosystem—the continent’s native trees have not developed the same defences.

Beavers fell trees to feast on their leaves and create dwellings from their trunks and branches. South American trees do not have the same defences as North American trees, which resprout when chopped down and emit protective chemicals when chewed.

A beaver constructs a dam near Ushuaia, Tierra del Fuego’s largest city. Beaver dams redirect rivers and replace flowing water with stagnant ponds, altering the kinds of wildlife that can thrive there.

Andres Pedro Osmolski, who goes by “El Gaucho,” organises beaver spotting tours on the land behind his home. He negotiated an agreement with the government to spare the beavers on his property for now so he can continue showing them to tourists.