1,329 Rare Snails Once Believed Extinct Reintroduced to Island off Morocco

A Desertas Island snail at Chester Zoo in Upton-by-Chester, Cheshire, England in 2021. Chester Zoo / Facebook

More than 1,300 critically endangered land snails have been released in the Ilhas Desertas (Desert Islands) archipelago off the Moroccan coast.

The reintroduction of the tiny molluscs to their native habitat followed the rescue of two obscure species of the snail from the edge of extinction, reported The Guardian. The snails hadn’t been recorded for over a century and were thought to have disappeared.

“If it goes as well as we hope, more snails will follow them next spring. It’s a huge team effort which shows that it is possible to turn things around for highly threatened species,” said Gerardo Garcia, curator of lower vertebrates and invertebrates at Chester Zoo in the United Kingdom, as the BBC reported.

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The pea-sized molluscs are native to mountainous Deserta Grande island, southeast of Madeira. Their habitat was destroyed by invasive mice, rats and goats that had been brought there by humans.

A wild refuge for the snails was restored on neighboring Bugio Island, where the invasive species were eradicated.

The reintroduction plan was coordinated by biologist Dinarte Teixeira with the Instituto das Florestas e Conservação da Natureza (IFCN) as part of the conservation program Help Desertas Snails, reported Madeira News. Participants in the effort included the Chester and Bristol Zoos and Mossy Earth in the UK, France’s ZooParc de Beauval and the International Union for Conservation of Nature’s Atlantic Islands Invertebrate Specialist Group.

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Four additional preliminary reintroduction projects are planned for 2025 and 2026. An ongoing monitoring program will analyze the reintroduced snails’ survival rate, as well as their potential impact on the island’s other mollusc communities. The data will be used to measure the conservation program’s success.

IFCN experts rediscovered populations of less than 200 individuals each of two subspecies of the tiny snail during conservation expeditions from 2012 to 2017, The Guardian reported. It had been feared that invasive predators had possibly decimated the species.

The snails were relocated to the zoos in France and the UK. The conservation science team, along with Madeira experts, constructed mini habitats for 60 of the snails at Chester Zoo as part of the breeding program.

“It was a huge responsibility to begin caring for them,” said Dr. Gerardo Garcia, head of ectotherms at Chester Zoo, as reported by The Guardian. “As a zoo conservation community, we knew nothing about them. They’d never been in human care before and we had to start from a blank piece of paper and try to figure out what makes them tick.”

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In order to protect Bugio Island’s fragile ecosystem, humans have not been allowed on the island since 1990.

“Within a few months we were able to crack the breeding of the Desertas land snails. Crucially, we were then successful in breeding multiple generations. This was key, because it meant we could then bring in the support of other zoos and establish a network, breeding them in the substantial numbers needed to have a chance of saving the species,” said Heather Prince, Chester Zoo invertebrate specialist, as The Guardian reported.

Each snail that has been reintroduced has an individual monitoring marker. If the effort is successful, many more of the endangered snails will be released.

“These snails are incredibly precious. The Desertas Islands are the only place in the world where they can be found and so we’re striving to do everything we can to give them the best possible chance for the future. For 100 years we thought they’d gone for ever, but now there’s new hope,” Teixeira added.

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