Guanacos are a close relative of llamas, alpacas and vicuñas, with pointy ears and pale brown fur. This wild camelid species, found in Argentina, Peru, Bolivia and Chile, is a cornerstone of Patagonia’s ecosystem as one of the only large, native herbivores in the region. They once roamed freely throughout Patagonia, numbering up to 50 million and serving as prey for many endemic predators. But due to competition with livestock and over-hunting, their estimated population is now around 2 million. Guanacos are charismatic megafauna, large and attractive animals that conservation groups use to garner support and funding.

In Argentina, some have sought to reintroduce guanacos into regions of the country where they had all but disappeared. Organizations are choosing wildlife translocation (the practice of moving a free-ranging group of animals from one location to another) over the slower and less certain process of rebuilding existing populations.

In 2018, the NGO Fundación Rewilding Argentina (FRA) released plans to transfer a group of guanacos from Parque Patagonia, a glaciated national park in the Santa Cruz province of southern Argentina, to the Luro Provincial Park, a reserve in La Pampa, 1500 kilometers (932 miles) north. The group’s name indicates their allegiance to rewilding, a framework for translocation that focuses on the restoration of earlier, more pristine ecosystems that are presumed to have a capacity to adapt and self-regulate. The new park is characterized by dry forest vegetation, savannas and a variable but generally warmer climate.

Supporters of these plans say they could help restore the guanaco to landscapes where it had once thrived. They hope that it will open the door to additional translocations further north in El Impenetrable National Park, a subtropical region with forests and wetlands. Though small guanaco populations survive in La Pampa, guanacos are “critically endangered” in the region. Santa Cruz, on the other hand, harbors an abundant guanaco population, with an estimated 1.1 million animals in 2015. In June 2023, some Santa Cruz cattle ranchers even complained of a guanaco overpopulation problem.

The governments of Santa Cruz and La Pampa partnered to enact the guanaco translocation plan, which was approved by the Argentinian Ministry of Environment and Sustainable Development, to be facilitated by FRA. The foundation’s website states the project “represents a great start to reintroduce the guanaco to many regions of Argentina where we have extinguished it.” To FRA and its backers, bringing guanacos from where they are abundant to where they are few in number seemed a logical choice.

But a group of Argentine researchers have criticized the move. “This management decision violates guiding principles for rewilding,” wrote five Argentine researchers in a letter in a leading ecology journal. Published in October 2023, the letter pointed out that while rewilding has garnered recent public attention and praise, it remains an uncertain realm. The authors noted a lack of scientific evidence and evaluation. They also raised procedural concerns about how management decisions were made, arguing that the government prioritized private objectives over local, publicly funded science.

When evaluating a proposed species translocation, experts agree that it is important to consider the possibility of genetic variation. Guanacos exhibit regional genetic differences. Thus the translocation could produce something known as anthropogenic-driven admixed populations, when individuals from two or more previously isolated populations interbreed due to human interference, sometimes reducing population fitness. In this case, the guanacos from Santa Cruz carry genes that adapt them to cold grasslands, a very different habitat from La Pampa’s warmer climate. If the two populations interbred, the unique genetic makeup of La Pampa’s smaller population could be overwhelmed by that of the Santa Cruz guanacos. If that were to occur, the La Pampa genes would become unavailable for future efforts to protect the species.

According to Ulises Balza, lead author of the letter, the benefits and risks of any animal translocation process must be discussed on a case-by-case basis. “Here, there was no such discussion,” wrote Balza in an email to GlacierHub. Balza pointed out that FRA highlighted only the potential benefits of translocating the guanacos, while the genetic risks were “completely ignored.”

Viorel Popescu, an associate research scientist in Columbia University’s Department of Ecology, Evolution and Environmental Biology, told GlacierHub that inadvisable conservation decisions are not uncommon. Popescu explained that successful cases of rewilding typically involve scientific backing and public outreach, but that many unsuccessful projects do not consider either the impact of the translocated animals on the recipient ecosystem or the effect of the novel environment on the translocated species’ ecology and behavior. “We often fail to learn from our mistakes, as is the case here,” he said.

Balza described this delegation of the approval process as quite unusual. “Normally you would have the governmental agencies approving their projects with some justification that can be more or less supported by information.” In this case, however, Balza said that despite all government technicians strongly advocating against the relocation based on the evidence, the ministry outsourced its management to FRA.

According to Marcos Mendoza, an anthropologist at the University of Mississippi, FRA’s power in this context might be attributed to its pre-established influence in Argentine conservation and governmental circles. FRA is a subsidiary of Tompkins Conservation,  a nonprofit environmental organization founded by American environmental philanthropists.

Tompkins Conservation has played a significant role in Patagonian conservation, pouring hundreds of millions of U.S. dollars into land rehabilitation and protection initiatives, but the organization is also a source of controversy. Critics have accused it of green neo-colonialism and conservation capitalism. They say Tompkins executes conservation initiatives at the expense of rural Patagonian communities by creating “privately protected areas,” which disrupt local systems of production and result in loss for local populaces.

An April 2023 landmark paper by Guerisoli and colleagues, published before the letter mentioned earlier, critiques Argentina’s overall rewilding policies and notes some of the same genetic risks, and specifically points to FRA’s past failures to take these concerns into account. Following this publication, FRA’s leaders threatened to sue the authors for defamation in June 2023, claiming that the paper had been “written in a violent manner.”

The scientists who wrote the paper responded with letters in two journals, the first in October 2023 and the second in November of the same year, accusing FRA of refusing to engage in constructive debate with the scientific community. “We strongly reject this baseless threat,” read the letter, saying that such discussions should be addressed respectfully, in an academic context.

It is unclear whether FRA is moving forward with their litigation efforts, and Mendoza noted that the legal ramifications of such a case would be difficult to assess. “The claim of libel made by FRA seems to be a meritless charge,” he said.

However, Argentine academics and scientists, particularly CONICET (Argentina’s main scientific government agency), are concerned about public funding for their research being cut going forward. Mendoza explained, “Scientists have been marginalized from the rewilding debate. Meanwhile, Fundación Rewilding Argentina… has used its institutional networks to drive conservation policy at a distance from potentially critical scientific voices.”

As climate change threatens biodiversity, guanaco populations in cooler regions, such as glacier-filled Patagonia, may be seen as replacements to losses elsewhere—but as this case shows, such solutions are complex, and there is no silver bullet for species restoration. Future rewilding decisions will require careful research, preparation and consultation of local communities to avoid similar controversies in the future.