Newenche walked alone.
He travelled more than 300 km, navigating the ragged peaks of the southern Andes and crossing a national boundary, from Chile into Argentina. Without a herd, a territory, or a mate.
When the young huemul ( Hippocamelus bisulcus ) was first seen in Lanín national park in early 2025, the appearance was considered historic. His solitude itself was the cause for celebration. In this part of Argentine Patagonia, the huemul had not been seen for decades and was considered virtually extinct. Only once was there even a flicker of hope: a few footprints found in 2006 .
A year later, Newenche is still there. Native to the Americas, the huemul is the continent’s most endangered deer with an estimated population of 1,500-2,000 . Newenche’s journey has reinvigorated a scientific and ethical question that divides conservationists: should we limit ourselves to protecting what is left of the natural world, or is it time to intervene with active recovery?
Rewilding, and the risks of intervention
In many ways, the huemul survived the Andes but not human contact.
“It is an extremely trusting animal that is not afraid of humans,” says Sebastian Di Martino, conservation director at the Rewilding Argentina Foundation ( FRA ). That trait proved fatal. Combined with indiscriminate hunting, competition with cattle, diseases transmitted by livestock and attacks by dogs, huemul populations collapsed during the 20th century. As valleys were urbanised and converted for agriculture, herds became isolated. Scientists estimate that barely 1% of the original population survives today.
For some conservationists, that history makes a case for intervention. Eduardo Arias, director of conservation at Chile’s Huilo Huilo biological reserve, argues waiting is no longer an option: “In such sensitive situations, the time has to come to stop being so contemplative and take active conservation seriously.” Huilo Huilo began breeding huemuls in captivity in 2005, starting with a pair and adding another female the following year. A decade later, Chile authorised the first releases into the wild. Today, Arias says, around 50 huemuls live freely, forming seven family groups.
Tralca, for instance, was one of the males released in 2016. Newenche is his son.
This approach is often described as rewilding , or active restoration: the deliberate reintroduction of species into landscapes where they were once wiped out, with the aim of restoring ecological functions. It remains deeply contested. Critics argue that moving animals is not simply a technical fix, but a profound intervention in complex systems that may have already shifted beyond reversal. A female huemul in Chile’s Torres del Paine national park, photographed in 2014. Scientists estimate that barely 1% of the original population of this species survives today (Image: Joao Barcelos / Alamy) Rewilders are broadly split into two camps, one being those who want to “leave everything alone”. The other believes the level of damage caused to ecosystems is so great that, as Di Martino puts it: “It is impossible to imagine that nature will recover on its own, as if by magic.”
Within the “active” rewilders, there are still divisions, particularly over the relationship between humans and nature. Some advocates start from the idea that “wild” ecosystems should function without human presence. “Our foundation wants to regenerate complete and functional ecosystems, which have everything they once had and, from that moment on, continue their evolution wherever they need to go,” explains Di Martino.
Others point to the complexities – or even impossibilities – of separating humans and nature. “Most protected areas are surrounded by productive areas,” says Alejandro Valenzuela, a researcher at the National Scientific Research Council of Argentina (Conicet). “So, what is being created is something prettier but it’s quite similar to a zoo, because it has no biological or geographical continuity. The species lack connectivity and all individuals become relatives of a few parents.”
Some question the impact of rewilding on rural communities. Advocates suggest nature tourism could be a novel economic outlet for the inhabitants of rewilded areas. But others argue it can lead to rural depopulation, and instead call for holistic solutions that consider socio-economic factors. The objections are not just philosophical or social but technical, too. “The manipulation and translocation of animals carries too many risks and must be carried out in accordance with the minimum guidelines established by the IUCN [International Union for Conservation of Nature],” says Valenzuela, adding that “at least in Argentina, I am not aware of any project that complies with them.” A male huemul being tagged with a satellite tracking collar during 2022 in the Río Toro private refuge, Santa Cruz province, Argentine Patagonia (Image: Franco Bucci) Hernán Pastore, a biologist and wildlife specialist at the National Parks Administration in Argentina (APN), lists these technical criteria for rewilding: solid evidence that the species existed in the area; understanding of the causes of its disappearance; assessment of whether the current environment is still suitable; genetic proximity of the specimens to be introduced; and guarantees that the original population will not suffer irreversible damage.
There are other important factors to consider: local participation, ecological connectivity to prevent inbreeding and long-term monitoring. “Too often, media or tourism impact is prioritised over ecological processes,” Valenzuela warns.
Di Martino says Rewilding Argentina follows the IUCN guidelines. Intervening in altered ecosystems
Nestled beside Fontana Lake, in Andean forests to the south-east of Argentina’s Chubut province, is the Shoonem breeding centre. This is the only facility in the country authorised to work with huemuls. Opened in October 2018, the 100-hectare space currently has four females, two males and five juveniles living in semi-captivity. Its director, the Swiss biologist Werner Flueck, argues the species’ failure to recover is not just down to hunting or habitat loss but more subtle ecological disruptions. For instance, the deficiency of trace elements in their diet, such as selenium and iodine. La Plata Lake in Chubut province, southern Argentina. The Shoonem breeding centre, which operates in this area, is the only centre of its kind authorised to work with Argentina’s huemuls (Image: Gabriel Rojo / Alamy) According to Flueck, until 150-200 years ago, huemuls followed a seasonal migratory pattern. They descended to the Patagonian steppes in winter and returned to the mountains in summer. That movement has been broken. “Human encroachment on the most productive valleys and plains has forced huemuls to live as refugees throughout the year in the remote heights of the Andes mountain range, where nutritional conditions are worse,” he says.
Studies carried out on huemul bones by Shoonem have revealed changes in the skull and teeth, caused by low levels of iodine and selenium in their new highland grazing areas. These changes have been detrimental to their ability to search for food and avoid predators. This in turn has contributed to the low average age of adult huemuls in the region, shrinking populations. When able to feed on the woody and herbaceous shoots of the steppe during winter, these huemels could theoretically compensate for such deficiencies.
Di Martino agrees confining conservation efforts to high-altitude refuges is a mistake: “We should make it easier for them to ascend and descend at different time of the year. Or start repopulating places where they used to live.”
Discussions around the creation of biological corridors are already underway at binational conferences between Chile and Argentina.
Lessons learned
Successful species reintroductions are not unprecedented in South America. For instance, the return of the jaguar to the Iberá wetlands in north-east Argentina. The first was released here in 2021 ; today, 50 jaguars live freely on San Alonso island.
Agustín Paviolo, a researcher at the Institute of Animal Diversity and Ecology at the University of Córdoba (UCO), is part of the team assessing this reintroduction: “The response in the food chain has been rapid, and is impressing us.” A capybara in Corrientes, north-eastern Argentina. Following the reintroduction of jaguars to Argentina’s wetlands from 2021, the capybara population has fallen by 80%. This is enabling grassland ecosystems to recovery from overgrazing (Image: Matthew Williams-Ellis Travel Photography / Alamy) The number of capybaras, the jaguars’ preferred prey, has fallen by 80% . Capybara behaviour has subsequently shifted, with herds avoiding areas where they are likely to be hunted. Grasslands have thus recovered, and areas once over-grazed by capybara are shrinking. While data is currently scarce, initial research by Adrián Di Giacomo, from Conicet’s Centre for Applied Coastal Ecology (CECOAL), shows fox numbers may also be declining – a boost for bird populations. “This change could increase the reproductive success of the Iberá collared yetapá (or Iberá capuchino), whose ground nests, eggs and chicks are preyed upon by foxes,” says Di Giacomo. Recommended For advocates of intervention, these outcomes show how reintroducing missing species can reshape ecosystems altered by human activity. For critics, they reveal how difficult it is to predict or control such processes. Oostvaardersplassen in the Netherlands is a stark example . Deer, horses and cattle were reintroduced here in the 1980s. Following a particularly harsh winter in 2017, however, thousands were struggling to survive and had to be culled.
Preparing the ground
Partly to avoid such outcomes, the IUCN has argued that a species reintroduction cannot succeed unless the pressures that led to its decline are addressed. At Huilo Huilo, that has meant zoning territory, removing feral cattle, strengthening surveillance and working closely with local communities and schools. This happened before any huemuls were released. “This has led to a very significant change in mentality over the last 20 years,” Arias says.
A similar process is underway in Lanín national park in Argentina, following reports of huemul releases in Chile. Since 2023, the park’s authorities have moved to control livestock, manage dogs and regulate tourist access. “A healthy forest should have an herbaceous layer, an intermediate layer with shrubs, a layer of young trees and then mature trees,” says María Rosa Contreras, who is coordinating Lanín’s habitat recovery project in anticipation of the huemul’s return. “All of that was being changed by livestock.”
People, too, need to become reaccustomed with the animal’s importance via environmental education, she adds: “We want the population to recover its social memory and remember that the huemul is our native deer.”
Newenche’s continued presence – and his occasional solitary strolls into the outskirts of the city of San Martín de los Andes – is closely monitored. Whether or not others arrive here will determine if rewilding becomes recovery, or remains an experiment. For now, Newenche waits alone to see if more huemul will follow him across the Andes.
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