Argentina Reintroduces Giant Otter to Iberá Wetlands After Local Extinction

Argentina formally marked a significant conservation milestone on June 30, 2025, with the successful release of giant otters, a species locally extinct, back into the Iberá Grand Park in Corrientes province. This action signifies the first time in the nation's history that a mammal declared extinct within its borders has been restored to its native habitat. The giant otter, scientifically known as *Pteronura brasiliensis*, had not maintained a breeding population in Argentina since 1986, with its disappearance attributed to uncontrolled hunting for its pelt and extensive habitat degradation, including the construction of large-scale dams.

The complex, eight-year preparatory effort was spearheaded by the Rewilding Argentina Foundation, an organization affiliated with Tompkins Conservation. This initiative required extensive international collaboration, involving the European Association of Zoos and Aquaria (EAZA) and various global zoos that furnished the foundational animals for the program. The initial family unit released comprised the breeding pair, Nima, sourced from the Madrid Zoo in Spain, and Coco, from Givskud Zoo in Denmark, alongside their two offspring, Pirú and Kyra, who were born in Iberá in late 2024.

The reintroduction methodology, which began planning in 2017, included devising regulatory precedents for international wildlife transfers, establishing captive breeding pairs to form cohesive family units, and inventing specialized harnesses equipped with GPS transmitters for post-release tracking. The giant otter, locally referred to as 'lobo gargantilla,' functions as a keystone species and the principal aquatic predator across the South American wetlands, historically ranging throughout much of the Paraná River watershed. These animals, which can reach up to 1.8 meters in length and weigh nearly 33 kilograms, regulate ecosystem health by maintaining fish populations with their specialized diet.

Iberá Grand Park, spanning over 756,000 protected hectares, provides an optimal sanctuary due to its abundant prey and vast protected area, crucial factors for the species' establishment. This conservation achievement is part of a broader strategy to reestablish top predators, following the earlier reintroduction of seven jaguars since 2021, which has brought the current jaguar population in the wetlands to an estimated 35 to 40 individuals. Furthermore, Rewilding Argentina is extending this recovery model to El Impenetrable National Park in Chaco province, where eight additional otters recently arrived for future release into the Bermejo River area, a location where the species had been extinct for an estimated 100 years.

Sebastián Di Martino, Director of Rewilding Argentina, stated that the otter's return is a decisive action to restore the ecological health of Iberá, while Corrientes Governor Gustavo Valdés noted the potential for increased, sustainable ecotourism opportunities for local economies. The successful breeding of the first cubs in Iberá in late 2024 underscores the viability of this innovative, internationally coordinated approach to reversing local extinction events.