A conservation journal is to release a study on an endemic Bermuda snail once thought to be extinct. A small colony of greater Bermuda land snail, Poecilozonites bermudensis, was discovered in an alleyway in 2014, about 40 years since the species, which can grow up to 23 millimetres long, was last seen in the wild.

Specimens were bred in specially designed pods at Chester Zoo in England and 106,000 snails, comprising adults and juveniles, were released in 27 locations across mainland Bermuda and offshore islands between 2019 and 2022.

Mark Outerbridge, a wildlife ecologist with the Department of Environment and Natural Resources, said: “Based on persistence, reproduction and expansion from each release site after at least one year from release, reintroductions to six offshore islands were considered successful, but those on the main island failed, likely because of higher predation pressure.

“Controlling predators — rodents, feral chickens, carnivorous snails — and safeguarding these offshore islands against predator incursion is essential to ensure continued survival of the reintroduced endemic snails.”

Six colonies of the snail are thriving and British media highlighted the mollusc’s recovery on February 7 — the International Union for Conservation of Nature’s Reverse the Red day, which celebrates efforts to restore ecological diversity.

An assessment of the animals by Oryx, the International Journal of Conservation, is forthcoming.

Dr Outerbridge said: “The greater Bermuda land snail proved to be tremendously resilient, they survived for decades in a tiny concrete urban environment and thrived in captivity in the UK.”

Despite the progress, the DENR hopes to have at least ten self-sustaining populations of the species and also the endemic lesser Bermuda land snail, Poecilozonites circumfirmatus.

Conservationists brought 3,000 lesser Bermuda land snails from Chester Zoo to the island in 2023, but are trying to figure out why attempts to restore the species, which grows up to 10mm long, have not yet been successful.

Gerardo Garcia, an animal and plant director at Chester Zoo, and Kristiina Ovaska, of Canadian-based Biolinz Envrionmental Research, also discussed restoring the greater land snail population.

Dr Garcia said: “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 — the fact the snails are firmly established in six areas is massive.”

Dr Ovaska added: “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.”

Dr Outerbridge said: “The species also serves as an example of how important it is to find good project partners whose combined efforts can make a measurable difference.

“Each of us, myself, Dr Ovaska, Dr Garcia and his team at the Chester Zoo, played a key role in seeing these snails rescued, cared for, reintroduced and studied.”