For years, the greater Bermuda snail existed only in museum collections and fading memories. The button-sized mollusk—a relic species with a lineage stretching back over a million years—had seemingly vanished from Bermuda's ecosystem, destroyed by habitat loss, pesticides, and invasive predatory wolf snails that devoured the smaller native species.
Then in 2014, researchers found a cluster of survivors slithering through an alleyway in Hamilton, Bermuda's capital.
What happened next became what conservationists describe as a "once in a career" achievement. An international partnership between Chester Zoo, London Zoo, Biolinx Environmental Research, and the Bermuda government launched a rescue mission. Starting with fewer than 200 individuals, experts at Chester Zoo bred the snails in specially designed pods, adapting husbandry techniques to discover optimal conditions for reproduction.
Dr. Gerardo Garcia, Animal and Plant Director at Chester Zoo, described tracking the growing populations "like a war game" with flags pinned across a map of Bermuda as release sites expanded.
The results exceeded all expectations. Over 100,000 snails were released starting in 2019, and six colonies have now firmly established across the Atlantic archipelago.
"They nearly vanished, so being able to say the snails are now safe from extinction is amazing," Garcia said. "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."
The snails serve crucial ecological functions, acting as both prey for larger animals and processors of vegetation, cycling nutrients through their habitat. Their recovery confirms what Ruth Davis OBE, UK Special Representative for Nature, called "what is possible when we collaborate across borders to restore nature."
Chester Zoo has now turned its attention to saving the lesser Bermuda land snail, applying lessons learned from this remarkable comeback.