A button-sized snail once feared extinct in Bermuda is now thriving after conservationists bred and released more than 100,000 of the molluscs. The greater Bermuda snail (Poecilozonites bermudensis) was found in the fossil record but believed to have vanished from the North Atlantic archipelago, until a remnant population was discovered in a damp alleyway in Hamilton, the island capital, in 2014.
After a decade-long international effort by conservation scientists, the government of Bermuda and Chester Zoo, where thousands of the snails were bred before being transported back to the islands, the species has been confirmed as safe from extinction. Tamás 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 snails, found only in Bermuda, had been hit by global heating and habitat loss, but their decline was accelerated by the introduction of predatory “wolf snails” and carnivorous flatworms. At Chester Zoo, keepers adapted existing snail husbandry methods to create optimal conditions for the snails to multiply, keeping them in specially designed pods.
Since 2019, generations of captive-bred snails have been returned to Bermuda and placed in protected wooded habitats with biosecurity measures shielding them from invasive predators. According to a population assessment to be published in Oryx, the International Journal of Conservation, the snails are now well established in six areas.
Dr Mark Outerbridge, an ecologist for the government of 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.” Dr Kristiina Ovaska of Biolinx Environmental Research added that the snails are vital for nutrient cycling in their habitat.
The Chester Zoo team is now focusing on breeding a second rare species, the lesser Bermuda land snail (Poecilozonites circumfirmatus).
