02/12/2021

Conservationists from the UK and Portugal launch dramatic rescue mission.

Speedy comeback: Two species of land snails, thought to be extinct for more than 100 years, have been bred by experts here at Bristol Zoological Society and at Chester Zoo.

Conservationists from the UK and Portugal have launched a dramatic rescue mission to save a group of rare snails from extinction.

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

Desertas Island

However, experts at the Instituto das Florestas e Conservação da Natureza IP-RAM have rediscovered tiny populations of two species of the snail, each consisting of fewer than 300 surviving individuals, on an isolated island in the Madeira Archipelago in the North Atlantic Ocean. The snails are now believed to be the very last of their kind on the planet. 


Now the snails are part of a unique conservation recovery plan supported by the International Union for the Conservation of Nature through the Mid-Atlantic Islands Invertebrate Specialist Group and Rewild.

It began after around 60 individuals from each group were carefully collected from the island and flown 1,500 miles to the UK, where specialists at Bristol Zoological Society and Chester Zoo are leading the last ditch attempt to boost numbers and save the species.

Invertebrate staff at both charity zoos, who are world-renowned for their technical knowledge and species-saving work, have created special breeding centres which closely replicate the perfect conditions for the snails to breed and thrive.

Mark Bushell, Curator of Invertebrates here at Bristol Zoological Society, said: “These snails are a vital part of the natural ecosystem on the Desertas Islands and are found nowhere else on the planet, so to be able to play a part in securing the future of these species is a huge privilege.

“We will draw on the wealth of knowledge and experience that we have from decades spent breeding and caring for a range of other threatened snail species, and use this to ensure that these species are given the best possible chance for the future.

“Collaborative projects such as this are testament to the vital role that good zoos play in safeguarding at-risk species, working together to protect threatened species and habitats all over the world.”

Desertas Island

The work being done by invertebrate keepers at Bristol Zoological Society builds on years of experience breeding other Critically Endangered snail species in climate-controlled conditions within Bristol Zoo Gardens’ Bug World.

Keepers here at Bristol Zoo Gardens are now caring for more than 50 Desertas Island land snails, alongside a Critically Endangered species of spider, also from the Desertas Islands, which the zoo helped bring back from the edge of extinction by establishing the world’s first breeding programme for the species five years ago.

Since then, keepers here at the Zoo have bred more than 1,500 Desertas wolf spiders from the first 25 spiders ever brought into captivity.

The Desertas Islands, where the snails were found, are now protected nature reserves under Portuguese and European law and have been recognised as biodiversity hotspots for rare invertebrates, birds and reptiles.

The snails were classified as globally extinct in the wild in 1994, but now, following this rediscovery, both species are listed as Critically Endangered by the International Union for the Conservation of Nature (IUCN).

Dr Gerardo Garcia, Chester Zoo’s Curator of Lower Vertebrates and Invertebrates, added: “These snails had not been seen for decades and were thought to have gone extinct, so urgent action was required when only a handful of these special snails were found clinging on to survival.

“Starting with just 20 of the last known individuals on the planet from each group, there was a lot of pressure to find answers quickly, but with the technical knowledge, scientific underpinning and the skills developed here at the zoo with other highly threatened invertebrates, our team was able to develop the ideal breeding conditions. 

Desertas Island land snail in the wild

“Now, with more than 1,200 safely in our care, we can say that we have prevented two magnificent species from becoming extinct, which is an incredible achievement.

“This is just the first step in our recovery plan and, looking ahead, the snails here will form a safety-net population and become part of an international breeding programme that provides a sustainable future for the species. 

“We’re also hopeful that many of the snails bred here will be reintroduced to some of the surrounding Desertas islands, once work is completed to restore habitat and remove the invasive species that have devastated the islands – allowing the snails and other endemic species to flourish.”

Dinarte Teixeira, Senior Technician for the Instituto das Florestas e Conservação da Natureza at Madeira, added: "This project is a dramatic call for action to protect these unique land snail species. They are currently restricted to small pockets of refuge, genetically isolated, having been fiercely predated by invasive mice. After more than 100 years without live records, their rediscovery enables us to implement immediate conservation actions directed to these snails.

“At the same time that the species rescuing programme was being secured, we started a mice control program to mitigate their impact on the snails’ populations. As the first step to controlling this predator, we hope to lead to the second phase of eradicating these invasive species. If successful, it will enable the snails’ population reinforcement in the mid-term, contributing to the long-term survival of the species in the wild.

“We are also eager to learn more about the species ecology and its requirements, where little is known. The field data collected will be necessary when deciding about future population reinforcement or species reintroduction in nearby islands.

“All critical information will be part of the species conservation plan. This master tool is being prepared by all the project partners and key stakeholders. With it, we are confident that we will be able to make the best-informed decision about the conservation of these unique land snails."

The bid to save the snails comes as they were feared to have already been lost forever and no surviving populations had been found for more than 100 years. The snails’ main threats are invasive mice and goat species – introduced by human settlers – predating on the snails and destroying their habitat.

While conservationists work to restore and replant the habitat on the islands, as well as managing the invasive animal populations, a number of the animals bred at Bristol Zoo Gardens and Chester Zoo will be reintroduced to new locations in the region. 

Some of the surrounding islands have largely been left untouched by humans and are free from the snails’ predators – providing a perfect sanctuary for the new boosted populations to thrive in the wild.

The successful project between leading wildlife conservation organisations Bristol Zoological Society, Chester Zoo, Mossy Earth and the Madeiran Government in Portugal, is set to be used as a blueprint for helping other threatened reptiles and invertebrates in the region. 

Tiago, Conservation Biologist at Mossy Earth, said: "The situation with Madeira's land snails is very worrying but we hope that this project will showcase how targeted efforts can turn things around. 

“From my time in the Desertas it has become very clear how important it is to have local naturalists and researchers that can dedicate themselves to studying and monitoring these rare species. 

“At Mossy Earth we often focus on neglected causes as a way to have the greatest impact and that’s why we are very excited about contributing to support the fieldwork needed to carry out this snail species rescue operation.”

Conservationists state that more than 20 other highly threatened species require urgent attention and this model can now be replicated to help prevent their extinction.

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