Over 1,300 tiny snails returned to the wild as conservationists bid to save species

More than 1,300 critically endangered snails have been released into the wild after being rescued from the edge of extinction, with a little help from a team of conservationists from the UK and Madeira.

The Desertas Island land snails were thought to have disappeared altogether, having not been recorded living for more than 100 years.

However experts at the Instituto das Florestas e Conservação da Natureza (IFCN) rediscovered tiny populations of two species of the snail (Discula lyelliana and Geomitra coronula), each consisting of fewer than 200 surviving individuals, on an isolated island called Desertas Grande in the Madeira Archipelago in the North Atlantic Ocean. The snails were believed to be the very last of their kind on the planet.

Sixty were flown to Chester Zoo, widely regarded as specialists in island conservation, where invertebrate experts worked to establish a unique breeding programme in a last-ditch attempt to boost numbers and save the species.

Drawing on their technical knowledge, specialists at the zoo managed to create the perfect conditions for the snails to thrive and made a breakthrough - successfully breeding both species for the first time ever in human care.

With a blueprint in place and the population beginning to boom, snails were sent from Chester to two other leading conservation zoos in Europe – Bristol (UK) and Beauval (France) – where fellow experts joined the efforts and set about expanding the population further.

Now, 1,329 snails raised in Chester have returned to Bugio Island as part of a reintroduction.

The small island has been specially selected as the main threats which almost wiped out the snails have been removed. Invasive goats, rats and mice, which have decimated the precious landscape, have been eradicated, while work to restore habitat on the island to its former glory has been carried out.

Dr Gerardo Garcia, Chester Zoo’s Head of Ectotherms, said:

“When the snails first arrived in Chester the very future of the species was in our hands. It was a huge responsibility to begin caring for them and we acknowledge the trust the IFCN, as a representative of the Madeira Government, placed in us.

“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 – how to care for them, how to create an environment in which they could flourish, and how to encourage them to breed. It’s a very complex conservation jigsaw – supported by constant information and feedback from our partners in Maderia who studied the island and the last remaining populations found there.

“These snails really were on the edge of extinction and the fact that we’ve now been able to give them a chance of making a comeback is testament to the efforts of many people – including our highly dedicated and skilled zookeepers who have spent countless hours caring for every individual snail. The ultimate aim is that the snails go on to thrive in their new home and the critical human interventions we’re making through reintroductions and reinforcements are no longer needed.”

Heather Prince, an invertebrate specialist at Chester Zoo, has been working on land snail conservation for more than 12 years – having also cared for threatened snail species from Polynesia, Bermuda, Cambodia and Malaysia. She has been involved at the outset of conservation breeding species which have seen eight species of snail reintroduced to the wild.

Heather said:

“Within a few months we were able to crack the breeding of the Desertas land snails,” said Heather. “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.”

Each of the snails reintroduced on Bugio has been individually marked so they can be carefully monitored on the island. If successful, many more snails will join them to help give the species a further boost.

Dinarte Teixeira, IFCN Conservation Biologist and Project Manager said:

“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 forever, but now there’s new hope.

“We’ll be monitoring the snails we’ve released incredibly closely over the coming weeks and months. Every single one of them has been marked with a colour code using a tiny amount of infra-red paint. This will allow us to track where they disperse to, how much they grow, how many survive and how well they adapt to their new environment.

“This reintroduction is the next, major step in our species recovery plan – following on from our habitat restoration programme, our pest control programme, our field surveys and our conservation breeding work. 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.” 

Tamara Canalejas, Curator of Ectotherms at Bristol Zoological Society, added:

“Our Ectotherm team have made remarkable breakthroughs with this successful breeding programme and we now have 500 critically endangered snails in our care here at Bristol Zoological Society.

“When we initially received the species we knew very little about them, but with the team’s experience and skills, and after years of research into how these tiny snails live and reproduce, we’re thrilled to be able to reintroduce them to the wild.

“The Ectotherm team have done an amazing job of breeding these tiny, or rather ‘dinky dinky,’ snails and we are very excited to be partnering with other conservation leaders as part of this programme as we prepare them for their big journey back to the Desertas Islands.”

Éric Bairrão Ruivo, Head of Conservation at Beauval Nature, stated:

“This first reintroduction of snails to the Desertas Islands is a perfect example of international cooperation to save critically endangered species, following an integrated ‘One Plan Approach’ promoted by the IUCN. It combines in situ and ex situ conservation to ensure a sustainable impact.

“The teams at Beauval Nature and ZooParc de Beauval are fully involved, whether in field logistics - such as eradicating invasive species or restoring habitats - or in conservation breeding. We have successfully bred both species of snails and currently host nearly 800 specimens.

“Thanks to these efforts, we will strengthen our contribution to the next reintroduction, planned for March 2025, by providing specimens born or raised at Beauval to join those from our partners at Chester and Bristol. With the support of the IFCN, we continue our mission to ensure the success of this vital program for biodiversity.”

Pictured - Two species of land snails, thought to be extinct for more than 100 years, have been bred by experts at Chester, Bristol and Beauval Zoos in a last-ditch effort to boost numbers and save the species.