Massive tortoise rewilding in Madagascar’s spiny forest strives to save fraught species

TAOLAGNARO, Madagascar – Gabriel Andriamanjaka holds the radiotracking aerial aloft and marches into a spiky forest thicket. Branches whip around his body as he pushes through in pursuit of his quarry. The beeps emitted by the receiver he carries grow more frequent as he closes in.

“Found it!” he calls back to us, pointing to a basketball-size bush trundling through the undergrowth. On closer inspection, the bush is actually a radiated tortoise tangled in twigs and leaf litter. Its shell is marked with numbers: “053.”

It’s a female, fitted with a radiotracking device when it was released in 2023 alongside hundreds of other radiated tortoises (Astrochelys radiata) into this 950-hectare (2,350-acre) community-managed forest in the Androy region of southern Madagascar. Andriamanjaka and his colleagues have been keeping an eye on the tortoises here at two-week intervals ever since.

As the monitoring team gathers around this particular individual, it turns tail and begins to negotiate a large twig. It loses its footing on the second step and stumbles. It shoots us a seemingly self-conscious glance, black eyes gleaming in the dazzling afternoon sunlight that easily penetrates the dry and spiny forest canopy.

Tortoise 053 is one of 4,000 subadult radiated tortoises so far liberated into a handful of well-protected forests in the region. And there are ambitious plans afoot to release many more — some 20,000 over the next five years.

Strong protection of their unique spiny forest habitats, their only home on Earth, will be key to ensuring their safety from a multitude of threats that have decimated wild populations. The tortoise rewilding program, led by U.S.-based NGO Turtle Survival Alliance (TSA), has found the most promising release sites to be forests managed and surrounded by Indigenous communities that have long-standing cultural affinity for the animals.

Hordes of tortoises

At the TSA’s Androy Tortoise Conservation Center (TCC), the red-orange soil is neatly apportioned into a series of fenced forest enclosures. Each is a hive of activity. Keepers shovel wheelbarrows of leafy greens into the compartments bustling with a total of 10,060 radiated tortoises as well as breeding colonies of critically endangered and endemic spider tortoises (Pyxis arachnoides) and plowshare tortoises (Astrochelys yniphora).

But this is just a portion of the total population of tortoises housed in a network of rescue centers operated by the TSA across the region. The centers care for more than 24,000 individuals confiscated from the illegal wildlife trade, most of which came from two enormous domestic seizures in 2018. As the only organization operating in the region with the capacity to care for confiscated tortoises and prepare them for release back into the wild, the TSA is struggling to cope with a near-constant stream of new victims.

Not only do tortoises arrive from domestic trafficking incidents, they increasingly turn up in overseas wildlife seizures. A May 2024 bust in Thailand, for instance, prompted one of the largest ever wildlife repatriation efforts to Madagascan shores, burdening rescue facilities with more than 900 tortoises. The past few months have also seen the TSA accept 142 tortoises returned from the Comoros and fend off pressure to take in casualties from Tanzania, Mozambique and Hong Kong.

Poaching presents the greatest threat to radiated tortoises: tens of thousands are plucked from the wild annually, according to studies. Growing to 13 kilograms (29 pounds), the adults are highly prized by poachers for their meat, which is considered a delicacy in towns and cities in the region. Meanwhile, the smaller-bodied juveniles are taken to meet booming demand in the international pet trade.

While they were once so thick on the ground in protected reserves that conservationists had to take care not to step on them, radiated tortoise numbers have plummeted by 80% over the last two decades. Tortoises reproduce slowly, so every loss due to poaching heavily impacts increasingly small and fragmented subpopulations. If nothing is done to stop the plundering, biologists calculate the species could go extinct within 20 years.

“We need to supply more tortoises for the wild population to thrive,” Hery Razafimamonjiraibe, TSA Madagascar country director, tells Mongabay during a visit to the species’ range in August. The best way to do this is by rehabilitating and releasing the many thousands of tortoises confiscated from the illegal trade, he notes. However, that’s not as straightforward as it may seem.

Animals confiscated from the trade are typically in poor shape when they first arrive at the centers, having endured cramped, crowded and unsanitary transit conditions. Most are malnourished and dehydrated, and all must be screened by veterinary staff for viruses, infections and other health problems before they can be mixed with other residents at the rescue centers.

“When they’re transported away from their natural habitat by poachers and then confiscated by the law enforcement, we have to quarantine them and do health checkups,” Razafimamonjiraibe says.

Sometimes injuries are acute, requiring treatment at the center’s dedicated vet clinic. Poachers have been known to poke holes in their shells to carry several at a time along a stick, and in the worst cases, animals have twisted bowels from being kept upside down.

The hungry inhabitants of TSA’s care centers chomp through more than 30 metric tons of food per month, an appetite that’s proved a boon for nearby villagers. More than 350 residents from four villages sell surplus produce to the Androy TCC, providing a vital income source in a region with few economic opportunities. Traditional livelihoods, like making sisal rope, earn about 5,000 ariary ($1) monthly, while selling tortoise fodder can bring in four times that amount weekly.

Tarikaze, a 30-year-old farmer, grows crops like watermelon, cassava and maize for her family, but says commercial farming has become unviable due to unreliable rains. She says she values the extra income from selling vegetable waste. “I can use the money to buy water, food and tea for my family. Also, when there is a sickness or death in the family, we can use the money to tide us over,” she says.

A unique ecosystem dwindles

Walking through the spiny forest in pursuit of Andriamanjaka and his tortoise-tracking team is an exercise in awareness. One wrong step and you could tear a sleeve or lose an eye on errant thorns that protrude from the vegetation all around. The path is lined with bulbous Pachypodiums and stately octopus trees whose tortuous, bright-green arms stand stark against the blue sky.

Besides the tortoises, these unique ecosystems are a refuge for a host of other endemic animals, including ring-tailed lemurs (Lemur catta), mouse lemurs (genus Microcebus), and Verreaux’s sifakas (Propithecus verreauxi) that feed almost exclusively on the forest vegetation. The spiny forest also has the highest rate of plant endemism in Madagascar: some 95% of the species here occur nowhere else on the planet, many of them on the brink of extinction.

Radiated tortoises feast on many of these species, too, particularly favoring the fleshy and juicy fruits of cactuses. Thus, the efforts to restore healthy wild populations of tortoises will also replenish their capacity to disperse seeds, in turn enhancing the spiny forest’s potential for natural regeneration.

The spiny forest ecosystem, however, is disappearing fast. As the region opened up to industrial-scale agriculture during the late 19th century, vast swaths of spiny forest were destroyed. Migration from outside the region continues to accelerate the forest loss and tortoise consumption and trafficking. Slash-and-burn clearing as well as cutting for firewood and charcoal, a staple fuel in an electricity-poor region, eat into remaining forest stands. As a result, the tortoises’ unique forest home now only exists in isolated pockets.

Protection into the future

Amid the habitat loss and relentless poaching pressure, coupled with Madagascar’s notoriously low capacity to enforce wildlife laws, finding and preparing well-protected release sites takes time. To maximize its chances of success, the TSA focuses on working with the Indigenous Tandroy and Mahafaly peoples living in the tortoise range who already value and protect the radiated tortoises. “We have to be strategic about where we release tortoises,” Razafimamonjiraibe says.

Tandroy and Mahafaly traditional beliefs portray tortoises as ancestral rainmakers capable of protecting villages against prolonged droughts and famine. Their culture forbids harming, eating or even touching the reptiles. So strong is the belief system that the sanctioning mechanism to enforce the taboo, called “Lilintane i Androy,” is inscribed as a bylaw in the Androy region.

The taboo appears to have had conservation outcomes for the imperiled species. Studies have shown that while tortoises have been lost in areas inhabited by people who don’t ascribe to the taboo and continue to hunt them, they prevail in landscapes where the taboo is followed.

Although it can take more than a year to gain the support of Tandroy and Mahafaly communities for the type of long-term tortoise conservation TSA aspires to, Razafimamonjiraibe says it’s worth the effort. “The success of the reintroduction program absolutely depends on building relationships with the communities on whose land the initiative works,” he says. “Without their support, nothing can be achieved.”

The community engagement has two main aims: first, to secure safe patches of intact spiny forest so that the tortoises have somewhere safe to live over the long term; and second, to directly protect the tortoises themselves from would-be poachers through locally led antipoaching patrols and intelligence networks.

The TSA has helped receptive communities create management plans to regulate potentially harmful practices like overgrazing, burning, and cutting for firewood in local forests. These plans have enabled the communities to gain legal recognition from the government to manage local forest resources.

The NGO also employs local district coordinators who train village volunteers in antipoaching patrol methods and safety procedures, as well as supports networks of village informants who help keep local police forces up to speed on poaching activity.

In return for the community’s efforts, the TSA has built schools, installed reliable and clean water systems, and supports livelihood initiatives such as setting up farmer cooperatives and designing value-added products like jams and natural fertilizers for residents to sell.

Fit for release

The Androy center has some 4,000 subadult tortoises now ready for release into suitable forests managed and protected by tortoise-friendly local communities. At the age of roughly 15 years, they’re at an optimal size: large enough to evade natural predators as well as poachers looking for small animals for the pet trade; and too small to be targeted for the meat trade — a win-win scenario.

Still, Vontsoa, a keeper at the Androy center, says he feels a little sad when a batch of tortoises leaves the center, even though he knows they’re returning to their natural habitat. “We’ve taken care of them so well at the center, but when they go back to the wild, they are alone. No one will give them food or water,” he says.

A subset of the expectant releasees will be fitted with GPS trackers, just like tortoise 053, so that monitoring teams can follow their activity to ensure they don’t stray into harm. The data from these devices help the team make adjustments to maximize the efficiency and success of their program.

Scientists are studying how the tortoises respond to a “soft release” period, for instance, whereby they spend several months in an enclosure within the release site where vet teams and keepers can still watch over them. “This acclimates them back to specific types of food and to the spiny forest,” says Lance Paden, a biologist at the University of Georgia, U.S., who’s studying the ecological outcomes of the program.

The soft release also gives the tortoises a sense of “site fidelity,” Paden says, so they’ll stay in the relative safety of the release site once the enclosure fences have been removed.

The monitoring efforts are also yielding new insights into the ecology and behavior of the little-studied species. Tracking teams have observed wild resident male tortoises make amorous advances toward released females, for instance. Even though these females are subadults and won’t reach breeding age for several years, Paden says these observations are a promising sign that the released tortoises are integrating well.

“We’ll be able to go back to the release sites in the future and see whether [the wild and released tortoises] are naturally reproducing and whether the offspring are surviving,” Paden says. “[The release program] is not just helping get the tortoises confiscated from trade back out into the wild, the idea is to have self-sustaining populations that we can protect into the future.”

Back at the release site, a volunteer member of the tortoise tracking team points out some medicinal plants approved for traditional use in the community-managed forest. The volunteer, who is not being named due to his additional participation in antipoaching patrols, is a member of the Tandroy community. He explains how the sense of ownership over local resources motivates his community to manage grazing pressure and wood cutting in the forest: “Our entire lives depend on the forest … Even the rain depends on the forest.”

Toward the end of the afternoon, we near the forest edge and come across a wild, unmarked tortoise. It lumbers across the forest track. The Tandroy volunteer kneels down next to it and places some fresh leaves on its back and pours a glug of water from a bottle over its shell.

“We do this as a blessing, to open the skies to have rain,” he says, referring to the taboo culture that prescribes an offering each time a tortoise is encountered, in recognition of its sacred position. “When we see the tortoises coming out of the forest onto the road, we know that it will rain.”

The next day, it rained. It was the middle of the dry season.

Citations:

O’Brien, S., Emahalala, E. R., Beard, V., Rakotondrainy, R. M., Reid, A., Raharisoa, V., & Coulson, T. (2003). Decline of the Madagascar radiated tortoise Geochelone radiata due to overexploitation. Oryx, 37(3), 338-343. doi:10.1017/s0030605303000590

Andriantsaralaza, S., Razafindratsima, O. H., Razanamaro, O. H., Ramananjato, V., Randimbiarison, F., Raoelinjanakolona, N. N., … Andriamiadana, S. (2024). Seed dispersal of Madagascar’s iconic baobab species, Adansonia grandidieri. Biotropica, 56(6). doi:10.1111/btp.13373

Nambinina, A., Sefczek, T. M., Frasier, C. L., Brown, A., Ratrimomanarivo, F. H., Razafiherison, R., … Louis Jr., E. E. (2022). Assessing population density of radiated tortoise (Astrochelys radiata) in Southwest Madagascar. Herpetological Conservation and Biology, 17(2), 370-377. Retrieved from https://www.herpconbio.org/Volume_17/Issue_2/Nambinina_etal_2022.pdf

This article by Carolyn Cowan was first published by Mongabay.com on 26 December 2024. Lead Image: An adult radiated tortoise eating an Opuntia cactus fruit crosses the main highway through the Androy region of southern Madagascar. Image by Carolyn Cowan/Mongabay.

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