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Giant anteaters lead biodiversity resurgence in Argentina’s Iberá

  • In 2007, the first pair of giant anteaters was reintroduced into Argentina’s Iberá reserve, a region from which it had gone extinct decades earlier.
  • The success of that program created the blueprint for reintroducing other native species, including Pampas deer, giant river otters, and red-and-green macaws.
  • The reintroduction program rescued anteaters from hunters and people keeping them as pets in northern Argentina.
  • Today, more than 200 anteaters live free in four population centers in the Iberá reserve.

In 2007, scientists at the Conservation Land Trust, now known as the Rewilding Foundation, released a giant anteater couple into the wild as part of a new reintroduction program.

While watching the animals, which they called Ivotí Pora and Preto, disappear into the forest of Argentina’s greater Iberá reserve — comprising Iberá National Park and Iberá Provincial Park — the scientists couldn’t help but feel concerned. These were the first giant anteaters (Myrmecophaga tridactyla) they had released. Despite having prepared the animals for months, exposing them to wildlife was an unknown challenge at this point. Would the couple survive?

Ivotí Pora (meaning “beautiful flower” in the Guaraní language) was the first anteater to enter the program. For more than two years, a family had been raising it as a pet in their house. They didn’t know it was illegal to raise anteaters domestically. When they learned of the project, they donated it to the team of biologists and veterinarians working on reintroducing the species in the province of Corrientes, where it had gone extinct.

“When we got her, we didn’t know if she was going to adapt,” said Alicia Delgado, who is responsible for the rescue center run by the Rewilding Foundation. Fourteen years have passed since then, and today, the foundation is much more certain about what it takes to be successful.

The giant anteater disappeared from Iberá in the 1960s. Image courtesy of the Rewilding Foundation.

In 2005, two years before Ivotí and Preto were set free, the foundation had already proposed returning lost species to the Iberá ecosystem. The advancing agricultural frontier and hunting in Corrientes had exterminated the giant anteater and other animals like the jaguar (Panthera onca), giant otter (Pteronura brasiliensis) and white-lipped peccary (Tayassu pecari). Without breeding pairs in the area, it became necessary to repopulate certain species by relocating them from other regions. The initiative seemed challenging.

But they needed a species to start with, and eventually decided on the giant anteater.

Science to the rescue

Scientists deemed the giant anteater, known locally as the yurumí, as having all of the most important characteristics for carrying out this mission.

“It’s a charismatic species,” Delgado said. “It wasn’t going to create a lot of problems during reintroduction. It wasn’t the same kind of start with the jaguar, which at that time could have raised some questions with local communities.”

The positive reception from different provincial governments was also a determining factor. The wildlife departments in Argentina’s northern provinces, where the giant anteater has wild populations, were all willing to donate specimens.

Although the anteaters in these areas aren’t close to extinction, they are threatened by their encounters with locals. “The problem is that people hunt in the forest with their dogs and can run into an anteater,” said Gustavo Solís, a veterinarian with the Rewilding Foundation. “When that happens, to preserve the integrity of the dogs, the owners often kill the anteaters.”

An average adult can weigh as much as 50 kilograms (110 pounds) and reach two meters (6.5 feet) in length. Image courtesy of the Rewilding Foundation.

The most common victims during these violent encounters are the mother anteaters with young cubs. In the first six months of life, anteater cubs depend on their mothers for nurturing and survival in the wild. The orphaned cubs, rescued by park rangers or brought into homes to be pets, are the most common participants in the project. “Eighty percent of the specimens we use have that origin story,” Delgado said.

Solís is in charge of the rescuing. He stressed the importance of acting swiftly after discovering a new anteater. “The key to success is to go quickly,” he said, explaining that a simple text message like “my neighbor has an anteater” can set off what is now a much-refined rescue process. These alerts come from residents, law enforcement or vets. All of them make up a system of collaborators developed over time.

Among the allied institutions working on the program, Solís mentioned national parks, zoos, bioparks and universities. Each of them helps make the rescue of the anteaters possible.

Giant anteaters tend to carry their young on their back. This one is a year old. Image courtesy of the Rewilding Foundation.

“We go to where the anteater is found with the primary goal of saving its life,” Solís said. The cubs tend to show signs of dehydration and malnutrition due to poor feeding habits. Once the first medical checks have been carried out, the local wildlife department takes care of the permits so that the anteater can be moved to the San Cayetano Rescue Center in Corrientes.

The center was designed by the Rewilding Foundation to receive and treat the giant anteaters. “It’s a unique experience, like a pediatric clinic just for these mammals,” Solís said.

Each time a new anteater comes in, the work is intense. The rescued animal starts with a monthlong quarantine. During that time, it goes through different checkups and analyses to detect any disease.

The small ones that arrive in bad condition barely weigh more than 1 kilogram (2.2 pounds). In that moment it’s hard to imagine that many of them will reach adulthood, weighing around 50 kg (110 lbs). “A 2-kilo [4.4-lb] cub can need up to 14 months to reach a sufficient weight and length for release,” Solís said.

The cubs that arrive at the rescue center are initially fed with a milk formula. Image courtesy of the Rewilding Foundation.

A place to grow up

Recovery depends on good feeding. In the initial growing phase, veterinarian Ana Carolina Rosas takes care of the anteaters. She says the work is complex because she and other researchers need to provide everything that a mother would to ensure the cubs develop.

The first food that rescued anteaters receive is a milk formula administered by bottle. “You have to be attentive to how they swallow and that they aren’t choking,” Rosas says.

In this phase, they’re very vulnerable animals that need feeding every two hours, and require a consistently warm environment. On the coldest days, the scientists cover the anteaters with blankets and give them hot-water bottles to heat their enclosures. However, the assistance can’t be too invasive. Too much care can stress the animals out or create an attachment that leads to dependence. “We should let them develop their instincts,” Rosas says, adding that it’s the only way the animals will adapt to living in the wild.

Within a few weeks, the anteaters grow out of their bottles and start to eat a more natural diet: worms and termites. Researchers noticed that this transition isn’t difficult for them even if they’ve spent most of their lives in captivity. “It’s an instinct. We’ve had anteaters just 15 days old that haven’t learned anything from their mothers. And at two months, when they come in contact with the ground, they start scratching in search of ants,” Rosas says.

Giant anteaters have a unique anatomy. The head is relatively small compared to the body, which can measure as long as 2 meters (6.5 feet). It’s easy to approach a young anteater, since it doesn’t have teeth, just a long sticky tongue. Its best defense are its claws, which it also uses to break open termite mounds, made of tightly compacted earth. In some ways, the anteater acts as a regulator of insect colonies.

See related: In search of the ‘forest ghost,’ South America’s cryptic giant armadillo

Eighty percent of the giant anteaters in the project are rescued from hunting or households that keep them as pets in northern Argentina. Image courtesy of the Rewilding Foundation.

Self-reliance in finding food and shelter, and being able to protect itself with its tail are behavioral requirements that researchers review before deciding to set an animal free. It must also weight at least 20 kg (44 lbs). “The individual has to be a juvenile. It should be at least one year of age to activate the wild behavior that will allow it to defend itself,” Rosas says.

When all of these conditions are met, the animal is taken from the primary facility and moved to a pre-release pen. One hectare (2.5 acres) in size, the pen is located in the middle of the greater Iberá reserve in the same environment where the anteater will eventually be released. For a month, it gets to know its new home. It also gets fitted with a collar equipped with a small transmitters, to allow researchers to monitor its movements for the first two years in the wild. “Normally, that’s how long it takes for them to settle into the area. In the case of females, we try to keep them in the collar for an additional year to monitor whether they’re capable of breeding,” Rosas says. The monitoring then continues via camera traps.

Rosas says choosing the right moment to free them isn’t easy. “It has to be spring or summer, the seasons with abundant food and less threats. That helps during the adaption period,” she says. If an anteater reaches the right weight and behavior in the winter, which in Argentina runs from June to August, researchers prefer to wait a few months before releasing it. They believe that letting it out in a favorable season increases the possibility of successful reintroduction in the wild.

The process of raising the cubs takes 14 months. Vets at the Rewilding Foundation are actively involved in their development. Image courtesy of the Rewilding Foundation.

A new home

The Rincón del Socorro reserve, spanning some 13,000 hectares (32,000 acres), was the chosen location for launching the reintroduction project. The scientists made the decision after carrying out an inventory of the area’s insects, analyzing its topography, and studying the amount of available pasture.

Ivotí and Preto, who came from a zoo, were the couple that rewrote the history of their species in Iberá. “They were already adults, so we had concerns that they might not survive. They were fighters,” Solís says.

Two years after her release, in 2009, Ivotí gave birth for the first time, to a cub that researchers named Tekobé (meaning “born free” in Guaraní). “This first birth made everyone so happy. It was a sign that she could adapt perfectly to the environment,” Solís says. Over the next several years, Ivotí had six cubs. “She gave Iberá so many offspring,” Solís says, calling Ivotí the matriarch of Rincón del Socorro.

The foundation has to date released 33 giant anteaters into Rincón del Socorro. In 2013, they started releasing individuals into the San Alonso area, covering approximately 10,000 hectares (25,000 acres), with the goal of creating a second community; they’ve released 23 anteaters there. Today, these are the two areas of the greater Iberá reserve that have self-sustaining giant anteater populations, requiring no additional attention from researchers. “We saw that the birth rate is higher than the mortality rate,” Delgado says of the two populations.

Once these two groups were formed, the Rewilding Foundation widened the scope of its releases. Today, it’s releasing the animals to strengthen the core numbers in the Carambola reserve and the San Nicolás area, which opened in 2018.

In their first months of life, giant anteater cubs are extremely vulnerable. They need to avoid cooler temperatures at all costs. Image courtesy of the Rewilding Foundation.

Throughout the last 14 years of work, the program has rescued more than 120 anteaters, of which 93 have since been released in the four sites. Through monitoring, researchers have counted more than 70 offspring born in the wild. Delgado estimates that around 200 anteaters live free in the Iberá forest today.

“The more population nuclei we can establish, the better. That’s why we should continue the reintroduction process,” she says. At the same time, the foundation is coordinating with regional authorities in Corrientes to establish biological corridors that will create connections between the different populations. “Having green land connections helps make the flow of fauna easier,” she says.

To learn how reintroduced anteaters made use of their new habitats, researchers from the government-funded Institute of Subtropical Biology, led by Yamil Di Blanco, published a study of 20 giant anteaters. They found that the animals avoided areas with livestock. “Apparently because [these areas] don’t have tall grasslands or dense forests, which they need for protection from natural predators and hunters and dogs,” Di Blanco said.

The study also considered whether future expansions of the giant anteater population could be limited by reproductive activity. Although any impacts will only be seen in the long term, it’s still something that researchers say needs to be taken into consideration.

Camera traps help identify specimens that have given birth. Image courtesy of the Rewilding Foundation.

Life lessons

Stories from some of the oldest human residents in the area tell of the giant anteater living in Iberá until the end of the 1960s. Younger generations didn’t know about the animal when the Rewilding Foundation went looking for references to its existence in local towns. What they discovered instead was an almost complete lack of knowledge about anteaters. “A lot of people thought they never existed in the area or they believed that they were like bears found in North America,” Delgado says. (The Spanish for giant anteater is oso hormiguero, literally “anthill bear.”)

Biologists and veterinarians understood that it was important to make the species known to nearby communities. At the start of the project, they visited several rural areas to educate residents about the animal’s characteristics and share information about the reintroduction. They held training sessions at schools, community centers and law enforcement agencies, even putting on theater performances to show people real-life stories of the anteaters.

“People started to love them. This work of raising awareness prompted the giant anteater to be declared a provincial natural monument in Corrientes,” Delgado says. With this measure, enacted in 2014, it became illegal to hunt or hold in captivity any giant anteaters from the province.

After two years of being free, a giant anteater has its tracking collar removed. Subsequent monitoring is carried out with camera traps. Image courtesy of the Rewilding Foundation.

The journey of saving the giant anteaters was a sobering one for the Rewilding Foundation team. “It’s the project that opened the door for all the others,” Delgado says.

In the years since the 2007 release of that first couple, and building on the lessons learned along the way, the organization has reintroduced Pampas deer (Ozotoceros bezoarticus), jaguars and red-and-green macaws (Ara chloropterus), among others. Delgado says that with the anteaters, researchers were able to build a base methodology: partnerships with other institutions, rigorous quarantine, steps for raising babies, installing pre-release pens, and carrying out monitoring of released individuals.

While births in the wild are no longer a novelty, Delgado says that at the foundation, they still respond with the same level of excitement as they did at the start. “Seeing animals that arrived in such sensitive condition become parents is hugely satisfying for the team,” she says. Fourteen years after Ivotí and Preto, the outlook in the Iberá is much more promising for the giant anteater. Bringing back a species that had gone locally extinct is also bringing back hope.

Banner image: The giant anteater was the species that laid the way for so many other reintroduction programs in Iberá. Image courtesy of the Rewilding Foundation.

This story was reported by Mongabay’s Latam team and first published here on our Latam site on November 30, 2021.

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