‘Extinct’ snail officially saved as conservationists bring rare species back from the brink

A button-sized snail once thought extinct has been officially saved after conservationists bred and released more than 100,000 into the wild.

The greater Bermuda snail (Poecilozonites bermudensis) was believed to be lost forever until a small surviving population was rediscovered in an alleyway in Bermuda’s capital, Hamilton, a decade ago.

Now, following an international effort, the species has been confirmed as safe and secure - a moment conservation experts describe as “once in a career.”

The landmark success - announced on Reverse the Red Day (February 7), which marks the global movement to undo biodiversity loss and ecosystems damage - has been achieved through a partnership between the government of Bermuda, a conservation researcher from the Canada-based organisation Biolinx Environmental Research and Chester Zoo, where thousands of snails were carefully bred before being returned to the Bermuda.

Tamas Papp, Invertebrates Assistant Team Manager at Chester Zoo, said:

“It’s every conservationist’s dream to help save a whole species – and that’s exactly what we’ve done. The greater Bermuda snail is tiny, but this is one of the biggest success stories in conservation. This scientific confirmation that we’ve saved them is testament to the role zoos can play in preventing extinction, and in the power of collaboration, and is something everyone involved will carry in their heart.”

Six colonies of the released snails have successfully established in Bermuda, an archipelago situated in the north Atlantic Ocean, six hundred miles from the nearest mainland.

This was confirmed by an assessment of how the snails are faring, forthcoming in Oryx, The International Journal of Conservation.

Dr Mark Outerbridge, a Wildlife Ecologist at the Department of Environment and Natural Resources in Bermuda, said:

“It has been extremely gratifying to be involved with this reintroduction programme and to see these snails back in Bermuda’s ecosystem again. It is remarkable to think we only began with less than 200 snails and have now released over 100,000.”

To boost population numbers, an expert group of scientists and keepers at Chester Zoo were entrusted with several of the snails in hope they could be bred off-site and returned to the wild.

Gerardo Garcia, Animal & Plant Director at Chester Zoo, was among the team that bred the snails in specially designed pods at the zoo and painstakingly released them in protected woodland habitats.

He said: “The fact the snails are firmly established in six areas is massive. These were not the only sites chosen for the introductions, but they are the ones where the colonies are growing and expanding in range. That itself is really important information, because not much was known about p. bermudensis.”

Keepers adapted existing snail husbandry methods to find the best conditions for p. bermudensis to multiply. Their findings are now part of the first conservation breeding guide for the species.

“They nearly vanished, so being able to say the snails are now safe from extinction is amazing. It’s an incredibly good feeling to make a huge difference for a species, and something conservationists might get to say only once in their whole career,” said Dr Garcia. 

“It is very rare for a team to be able to announce that, having brought animals into human care and released them, their work is done.”

Snails are among the least researched animals on the planet, and among the most vulnerable to extinction.

Endemic snails in Bermuda have been affected by habitat loss and climate change, and their decline was accelerated by the introduction of predatory ‘wolf snails’, and carnivorous flatworms which ate the much smaller native species. This had a broader impact on the Bermuda ecosystem.

Dr Kristiina Ovaska from Biolinx said:

“Bringing back the snails into their natural habitats is important for the conservation of this species and is part of restoring damaged ecosystems. The snails function both as prey for larger animals and as consumers of live and decaying vegetation, so they are vital for turning over nutrients within their habitat.”

The return of p. bermudensis was carefully planned. Reintroduction areas were selected and monitored in a process Dr Garcia described as ‘like a war game’, with expanding populations represented by flags on a map.

The snails’ long-term recovery goes hand-in-hand with nature regeneration projects carried out by the Bermuda government.

The success of the p. bermudensis project allows the Chester Zoo team to focus its efforts on a second rare species of snail, the lesser Bermuda land snail (Poecilozonites circumfirmatus).

In the future, climate change and environmental issues may affect the newly established p. bermudensis snail colonies, but the team is confident they now know how to reinforce the population quickly and effectively.

The project has already received wider recognition.

Ruth Davis OBE, UK Special Representative for Nature, said:

"Bringing Greater Bermuda snails back from the brink of extinction is a remarkable achievement. This an example of not only brilliant conservation science, but what is possible when we collaborate across borders to restore nature and reverse biodiversity loss.”